Portable Appliance Testing procedure
Document No:
CU/09/P/2.0
Policy Ratified by:
Portable Appliance Testing group
Date:
March 2014
Area Applicable:
University Campus Sites
Review Year
2017
Impact Assessed
Page 1 of 25
Document History
Author(s)
Date
John Frayling
Portable Appliance Testing group
Revision
Number
Date
Amendment
2009
October 2013
Name
1.0
Oct
2013
Full review and up-date
Mike Turner
2.0
March
2014
Full review and up-date
Richard Steed
Approved by
Page 2 of 25
Contents
1. Purpose ................................................................................................................................ 3
2. Scope.................................................................................................................................... 4
3. Definitions ............................................................................................................................. 4
4. Responsibilities ..................................................................................................................... 5
5. Arrangements ....................................................................................................................... 6
6. Measuring and monitoring ....................................................................................................10
7. Legal requirements ..............................................................................................................11
8. Further guidance: .................................................................................................................11
Appendix 1: Definitions ............................................................................................................12
Appendix 2: User checks. ........................................................................................................14
Appendix 3: Formal visual inspection (recorded) ......................................................................15
Appendix 4: Combined inspection and test, (recorded) ............................................................16
Appendix 5: Potentially sensitive electrical equipment..............................................................17
Appendix 6: Example applications:...........................................................................................25
1. Purpose
1.1
This Portable Appliance Testing (PAT) procedure and guidance ensures that Cardiff
University fully discharges its duty regarding the use and maintenance of electrical
equipment, with robust management and control systems in place to protect staff,
students and visitors.
This approach is necessary to protect staff, students and visitors from the risk of electric
shock and/or burns when using and maintaining portable electrical appliances: electricity
can kill, even non-fatal electric shocks can lead to severe and permanent injury.
Poorly maintained or inappropriately used electrical equipment also presents a significant
fire risk to buildings and infrastructure across the University.
This procedure and guidance therefore ensures the University discharges its duty to
provide safe portable electrical equipment, maintained and fit for purpose: the
effectiveness depends on physical precautions, and the co-operation of every member of
staff, student and visitor.
Page 3 of 25
2. Scope
2.1
This procedure and guidance covers all associated use of portable electrical equipment
at the University, in particular:

Electrical equipment brought into the University through routine procurement.

Personal electrical equipment brought into the University for university business.

Personal electrical equipment brought into the University for personal use.
Please note: Building fixed wiring, or equipment not connected via a 13 Amp plug or
equivalent are not covered by this procedure.
3. Definitions
The following are only the key PAT definitions. Please see Appendix 1 for a full list.
3.1
User checks. Not recorded. Before each use, the user is required to carry out simple
visual checks on the equipment. In practice these ‘user checks’ take very little time
and ensure any obvious damage or deterioration are identified. See Appendix 2 for
detail
3.2
Formal visual inspection. Recorded. Over time all electrical and mechanical
equipment require some form of preventative maintenance, over and above basic ‘user
checks’. A significant majority of related problems are identified via this quick, recorded
process.
See Appendix 3 for detail.
3.3
Combined inspection and test. Recorded. Whilst visual inspection will identify most
safety related issues, combining these with formal testing, (i.e. with test equipment),
will ensure even hidden faults are identified. See Appendix 4 for detail.
3.4
Class I: Earthed equipment. For safety reasons, Class I equipment is connected to
earth through its power supply cord. If that earth connection fails, an electrical fault
developed within the equipment may result in persons touching the equipment
receiving an electric shock. A good earth connection is therefore critical with Class I
equipment: the combined inspection and test specifically confirms that this connection
is sound.
3.5
Class II: Double insulated equipment. Class II equipment has a second insulation
layer within that prevents accidental contact with live parts, even if there is a fault.
Unlike Class I equipment, the extra insulation within Class II equipment means no
earth connection for user safety, even if the item has a metal casing. Class II
equipment does not therefore need a combined inspection and test, requiring instead
on a simpler user check and visual inspection routine.
Class II equipment is marked with the symbol
. If this is not visible, then assume
that the item is a Class I appliance, and carry out a full combined inspection and test.
Page 4 of 25
4. Responsibilities
4.1
Heads of Colleges / Chief Operating Officer. To satisfy their duty, Heads of College,
/ the Chief Operating Officer shall ensure that there are robust systems in place for the
competent maintenance and procurement of electrical appliances, and for the
monitoring of conformance against University expectations.
4.2
Heads of Schools and Directors. Heads of School and Directors are responsible for
ensuring that systems are in place to identify and maintain electrical equipment
brought into the University to be used by their School / Department either through the
normal procurement route or personal electrical equipment brought in for University
use.
In addition the Head of School / Director is responsible for ensuring that mechanisms
are in place to communicate electrical safety information through the School /
Department.
4.3
Managers and Supervisors. Managers and Supervisors are responsible for ensuring
that any electrical equipment brought into areas under their control are tested,
inspected and maintained for electrical safety and for ensuring compliance with this
procedure.
In addition, ensuring staff and students under their control are aware of the hazards
associated with electricity and the procedures and controls to mitigate the hazards.
4.4
Staff. Staff are required to inform their manager / supervisor of any electrical
equipment brought into the University, either through the normal procurement process
or personal equipment brought in for university use.
Staff are also required to carry out a ‘user check’ (see: Appendix 2) before operating
any electrical equipment either provided for University business or for personal use.
4.5
Students. Students shall carry out a ‘user check’ before operating any electrical
equipment either supplied by the university or personal items.
Note: The following responsibilities apply specifically to inspecting and testing
‘sensitive’ portable electrical equipment:
4.6
Equipment ‘owner’, (for example PI, Lab manager, primary user or equivalent).
Before any inspection and test, the owner, or primary user of the sensitive equipment
under test shall be responsible for clear identification of the full extent of the
equipment, (it may span several connected items). All potentially hazardous power
supplies and data connections shall be identified and isolated.
In addition, ensure that no equipment power supply can accidently or automatically reenergise whilst it undergoes a routine inspection and test.
4.7
Competent person carrying out the combined inspection and test. Before
commencing a test sequence, the competent person shall liaise with the equipment
owner, or primary user, to verify the correct equipment, and ensure all potentially
hazardous power or data connections are correctly isolated/made safe.
Once identified, label individual power supply cables, power packs, etc., to assist its
future test and maintenance. The competent person carrying out the test then in effect
becomes a ‘duty holder’ for the short period that they are in control of the apparatus.
Page 5 of 25
5. Arrangements
5.1
Inspection prior to first use
All newly purchased portable electrical equipment must undergo, as a minimum, a brief
visual inspection before its first use, and at appropriate intervals through its working
life. A visual inspection is required of even brand new equipment, to determine if any
damage in transit, and that the equipment is appropriate for the intended environment,
etc.
The process:
Start
Electrical equipment newly
brought into the University:
Has it been
purchased
through the
University?
Inform local manager / supervisor
item must undergo portable
appliance testing by a competent
person, and be tested before use.
No
Yes
Conduct a brief visual
inspection prior to first use.
Inform local manager/supervisor
that the item is to be placed on
the routine cycle of portable
appliance testing.
Yes
Passed all
necessary
tests?
No
Do not use: quarantine, disable or
withdraw item from use.
Discard through the University
waste electrical equipment
system (WEEE).
No
Can the
equipment be
repaired?
Yes
Fig 1: Inspection prior to first use
N.B. The above includes all personal / private electrical equipment brought into the
University for University business.
Page 6 of 25
5.2
Inspection prior to first use: in practice.
In practice a visual inspection of portable electrical equipment prior to its first use need
take very little time: any external damage is usually immediately evident.
Focus on the following key areas:




Ensure the plug and mains power lead are undamaged.
Ensure the fuse is appropriate for the rating of the appliance.
Ensure the equipment casing is free from obvious defects.
Ensure the equipment is suitable for the intended environment.
All new equipment:
Visually check plug, power
lead, and equipment casing
for any obvious damage.
Fig 2: Focus on plug, lead and casing
Enter the equipment details onto the appropriate register, so that it may be formally
inspected and tested in line with the agreed School / College PAT interval(s).
5.3
‘Generic’ PAT Risk Assessment
The process of risk assessment underlies safe provision, use and maintenance of
portable electrical equipment. For most portable electrical equipment individual PAT
risk assessments are not required: to avoid duplication, group similar equipment under
the same ‘generic’ PAT risk assessment. The stages are broadly as for any risk
assessment:
1.
Identify the
significant
hazards from
the equipment
2.
Decide who
could be
harmed,
and how
3.
Evaluate the
risk and decide
on necessary
precautions
4.
Record the
findings, and
implement them
5.
Review and
update the risk
assessment as
necessary
A generic PAT risk assessment would consider typical hazards, for example:

Local environment

Slips and trips

Adjacent equipment

Electric shock

Manual handling

Lone working, etc.
A generic PAT risk assessment identifies the broad range of control measures
necessary for that group of similar electrical equipment - the assessment would be
suitable and sufficient, but of a ‘generic’ nature.
Page 7 of 25
5.4
Key risk factors
Different types of portable electrical equipment will likely require different inspection
and test periods. For example a 240V drill used regularly in a workshop would require
more frequent checking than, (say), a serviced photo copier in an administration office.
Traditionally all portable electrical appliances in a building were inspected and tested
every 1-2 years, regardless of how often the equipment was used. The approach today
may be based on risk: and will depend on factors such as the equipment itself, the
local environment, and results of previous checks for example.
Rather than simply following a prescriptive time interval, (of say every 2 years), the
following 7 risk factors may be taken into consideration:
Risk Factor:
Considerations:
 The
environment
Consider how the local environment affects equipment. For example: the
significant differences between an office, laboratory, workshop, public area, etc.
 The user
Consider how experienced the user is. For example: is the equipment likely to be
used by a member of staff, Undergraduate or Post Graduate student, etc.?
 Equipment
construction
Ensure equipment selected is of an appropriate and durable construction.
It must be matched to the particular demands of the situation.
 Equipment
type
Equipment that relies on an earth connection, (Class I), is higher risk than similar
equipment where the safety is not dependent on this connection, (Class II).
 Frequency
of use
Equipment intended for frequent / continuous use must be so designed, and able
to cope with extended periods of operation, possibly with minimum maintenance.
 Installation
method
Consider local isolation arrangements, and cable management, (e.g. mechanical
risk to power supply cord).
 Local
incidents
Any previous incidents with the equipment may indicate a review and alternative
choice of equipment is required.
Table 1: Risk factors to determine inspection frequency
By considering the above risk factors in context, the most appropriate and justified test
regime for portable electrical appliances can be established.
Where there are similar circumstances, the above approach can be applied to either
individual portable electrical appliances, or to whole groups of similar equipment.
Page 8 of 25
5.5
Similar equipment, different environment
Figure 3 below shows how the overall risk from the same portable appliance would
vary in relation to changes in its local environment. In the example shown, the test
interval for a traditional desk top computer in a dusty workshop will likely be much
shorter than an identical computer used in an administration office, (i.e. a less harsh
environment).
If a generic test interval of (say) 2 years was applied to both PC’s, then the harsh,
dusty workshop environment would not be taken into account, and that PC may have
exposed users to unacceptable risk long before the 2 year inspection and test
identified this.
Risk assessment to focus on key factors:
Risk
assessment
’key factors’
Test and inspection periods
Key factors
3
mths
6
mths
1
year
2
years
3
years
4
years
The environment
The user
Equipment construction
Equipment type
Higher risk
Lower risk
Frequency of use
Installation method
Incident records
Computer
used in a dusty
workshop.
Same
computer in an
admin office
Fig 3: Risk assessment based test frequency, (extracted from OSHEU PAT training course)
5.6
Inspection periods
PAT inspection periods are determined locally through risk assessment. Take account of the
key risk factors listed previously (5.4). This risk assessment process must be documented,
particularly where extended test periods are proposed.
The following table is based on Health and Safety Executive guidance document INDG236.
The test periods shown are initial guidance only: over time, local circumstance and written
evidence may show trends, whereby the test periods can be extended, (or shortened).
Page 9 of 25
User
checks
Formal visual
inspection
Combined
inspection & test
No
No
No
No
2-4 years
No if Class II,
otherwise up to 5
years.
Not hand-held. Moved
occasionally e.g. fans, table
lamps
No
2-4 years
No
Hand-held.
Yes
6 months – 1 year
No
Yes
6 months – 1 year
1-2 years
6 months - 4 years,
depending on type of
equipment it is
connected to.
1-5 years,
depending on
type of equipment
it is connected to.
Equipment / Environment
Battery operated: (less than 40 volts).
Extra low voltage: (less than 50 volts AC), e.g.
telephone, low voltage desk lights, etc.
Equipment rarely moved, and not hand-held in
use. E.g: desktop PC’s, VDU screens,
photocopiers, fax machines, etc.
Class II.
(double
insulated
Earthed equipment (Class I). E.g. electric
kettles, some floor cleaners, some kitchen
equipment and irons.
Power cables.
Mains voltage extension leads.
Yes
Battery charging equipment, etc.
Table 2: Initial test periods
Note: Cables, leads and plugs connected to Class II equipment should be maintained as part of that
equipment. Cables, leads and plugs not dedicated to an item of equipment should be maintained as
individual items as appropriate.
6. Measuring and monitoring
6.1 Proactive and reactive PAT safety measures
The University has established procedures for measuring and monitoring its health, safety
and environmental performance on a routine basis, including any related electrical incidents.
Measuring and monitoring is conducted at both central University level, and at School and
Professional Service level. The approach taken includes:

Proactive electrical safety, (confirmed by general workplace inspections, Local
Building Group meetings, Fire Warden checks, Annual Returns, etc.).

Reactive measures such as appropriate disposal of faulty electrical appliances,
related incident investigations, and monitoring in response to any trends identified by
the local PAT regime, raised by staff, students or visitors.
Page 10 of 25
6.2 Corrective Action Procedures
Should the above identify any significant deviation from acceptable safety measures, (or a
repeated number of similar occurrences), then if the issues are not addressed within an
appropriate given timescale, a formal non-conformance may be issued.
(see ‘Corrective and Preventive Action Procedure for Safety Health and Environment’).
7. Legal requirements
Principal legislation relating to portable appliance testing at Cardiff University is:

The Health and Safety at Work Act 1974.

The Electricity at Work Regulations 1989.

The Electrical Equipment (Safety) Regulations 1994

Provision and Use of Work Equipment Regulations 1998.

The Management of Health and Safety at Work Regulations 1999, and

The Waste Electrical and Electronic Equipment Regulations 2006.
The Electricity at Work Regulations relate specifically to the use and maintenance of
electrical equipment: the central requirement being that electrical systems and equipment
are maintained, so far as reasonably practicable, to prevent danger. This requirement covers
all items of electrical equipment including fixed or portable equipment.
The above regulations do not specify what needs to be done, or how frequently. This allows
risk-based controls: appropriate to the risk rather than an inflexible test regime.
8. Further guidance:

Contact Purchasing for the current university preferred contractor for PAT
services.

Health and Safety Executive guidance on PAT can be
http://www.hse.gov.uk/electricity/faq-portable-appliance-testing.htm
found
at:
Page 11 of 25
Appendix 1: Definitions
User checks. Not recorded. See Appendix 2 for detail.

Before each use, the user is required to carry out simple visual checks on the
equipment. In practice these ‘user checks’ take very little time and ensure any
obvious damage or deterioration are identified. See Appendix 2 for detail.
Formal visual inspection. Recorded. See Appendix 3 for detail.

Over time all electrical and mechanical equipment require some form of
preventative maintenance, over and above basic ‘user checks’. A significant
majority of related problems are identified via this quick, recorded process.
Combined inspection and test. Recorded. See Appendix 4 for detail.

Whilst visual inspection will identify most safety related issues, combining these
with formal testing, (i.e. with test equipment), will ensure even hidden faults are
identified.
Risk. See Appendix 5 for detail.

In this context means risk to the safety of persons using a portable electrical
appliance: from electric shock, burns or fire. However, regarding particularly
sensitive electronic equipment, this itself may be at risk from a combined
inspection and test.
Risk assessment. Recorded.

In this context means a suitable and sufficient assessment of risk to which the
user of the equipment, (or those nearby), are exposed.
Generic risk assessment.

In this context, to avoid duplication similar appliances may be grouped under a
single ‘generic’ risk assessment. However, subsequent control measures only
apply to similar electrical appliances, used under similar circumstances.
Dynamic risk assessment.

In this context, a generic risk assessment as above, but dynamically tailored on
site to control a series of unique equipment hazards.
Class I: Earthed equipment.

For safety reasons, Class I equipment is connected to earth through its power
supply cord. If that earth connection fails, an electrical fault developed within the
equipment may result in persons touching the equipment receiving an electric
shock. A good earth connection is therefore critical with Class I equipment: the
combined inspection and test specifically confirms that this connection is sound.
Page 12 of 25
Class II: Double insulated equipment.

Class II equipment has a second insulation layer within that prevents accidental
contact with live parts, even if there is a fault. Unlike Class I equipment, the extra
insulation within Class II equipment means no earth connection for user safety,
even if the item has a metal casing. Class II equipment does not therefore need a
combined inspection and test, requiring instead on a simpler user check and
visual inspection routine.

Class II equipment is marked with
symbol. If this is not visible, then assume
the item is a Class I appliance, and carry out a full combined inspection and test.
Class III: Separated extra-low voltage equipment.

Class III equipment, sometimes called ‘safety extra-low voltage’ equipment, relies
on protection against electric shock from a supply not exceeding 50 volts a.c,
(more likely 24 or 12 volts). This is achieved via a built in safety-isolating
transformer, with no earth in the supply or on the equipment.

Class III equipment is marked with a
III
symbol.
Fault protection.

This provides protection where exposed metalwork of electrical equipment has
become live due to a fault, (i.e. breakdown of basic insulation). Protection is
generally by adequate earthing and automatic disconnection of supply, or the use
of double or reinforced insulation (Class II above).
Potentially sensitive electrical equipment.

Equipment considered potentially at risk of damage if subject to standard PAT.
Such equipment does not necessarily also have to be unique, or have a high
intrinsic value, etc.
Protective Earth (PE).

A low impedance path that ensures all exposed conductive surfaces remain at the
same electrical potential as the Earth, (to avoid persons using the equipment
receiving an electric shock if a fault has occurred). Not expected to carry any
current except under fault conditions.
Functional earth (FE).

A separate low impedance path to enhance the operation of the equipment,
(interference suppression, surge protection, common reference point, etc.). Does
not form part of any protective earth, sometimes called ‘clean earth’. Expected to
carry current under normal operating conditions.
Page 13 of 25
Appendix 2: User checks.
All users of portable electrical equipment should carry out a ‘user check’ prior to operating
the equipment. No formal training is required, however, the checks should include:
Inspect outside of plug for damage.
Inspect the cable for damage.
Ensure no taped or inappropriate joints.
Inspect for signs of overheating.
Inspect for obvious damage to the cover(s) of the equipment.
Notes:
If any signs of damage are found, the
equipment must not be used.
These simple user checks do not need
to be recorded.
Page 14 of 25
Appendix 3: Formal visual inspection (recorded)
Formal visual inspection of portable electrical equipment is relatively straightforward, and will
identify most electrical faults. Staff trained with basic electrical knowledge may carry this out.
In addition to the basic User Checks, (Appendix 2), formal visual inspection should ensure:

the equipment is being used in accordance with the manufacturer’s instructions;

the equipment is suitable for the job;

there has not been any change of circumstance; and

the user has no related concerns with the equipment.
Formal visual inspection includes checks carried out by the user and, where possible, will
include removing the plug cover and checking internally that:

there are no signs of internal damage, overheating or water damage to the plug;

the correct fuse is in use, (not a piece of wire, etc.);

all wires, particularly the earth where fitted, are attached to the correct terminals;

all terminal screws are tight;

the cord grip is securing the outer part, (sheath), of the cable tightly; and

no bare wire is visible other than at the terminals.
(N.B. Moulded plugs are permanently sealed in manufacture, and are not designed to open).
The formal visual inspection process is:
Confirm
equipment.
Fully isolate.
Seek help if
unsure.
Complete
without
moving the
equipment if
possible.
Record a
brief
description,
model, type,
etc.
Undo/check
plug, cord(s),
and covers
for any signs
of damage
Note any
concerns,
repair or
advise as
necessary.
Page 15 of 25
Appendix 4: Combined inspection and test, (recorded)
Persons required to carry out combined inspection and test must be competent to do so.
In this context, competency is a combination of experience, instruction, and formal PAT
training. Appropriate training to safely undertake University PAT is available via OSHEU.
Whilst visual inspection identifies most safety related issues, when combined with formal
testing, hidden faults are identified, (i.e. using calibrated test equipment).
Combined inspection and test therefore comprises the following:
1. A formal visual inspection (Appendix 3), to identify any obvious equipment faults.
2. Identify the class of electrical appliance (Class I, II or III).
3. Earth Continuity, (if appropriate).
Class I equipment requires an effective, low resistance earth path from the earth
pin in the mains plug of the equipment, along the power supply cord, to the
equipment casing. If that earth connection fails, and an electrical fault develops
within the equipment, persons touching it may receive an electric shock.
4. Insulation resistance, (if appropriate).
For Class I and Class II equipment, the Insulation Resistance test identifies any
breakdown of insulation between the protective earth, and live and neutral parts
of the equipment and its lead.
6
Test the equipment operation, if safe to do so.
Equipment successfully passing the above would receive a Pass label, and be
returned to use.
7 Fail: label, disable, remove from use.
Note: Be aware that although an item of equipment may ‘Pass’ a combined inspection
and test, it does not necessarily follow that it actually works, or will continue to work!
Page 16 of 25
Appendix 5: Potentially sensitive electrical equipment
(Laboratory, Workshop, LAN room, etc.).
Contents:
1
Overview
17
2
Purpose
17
3
Scope
18
4
Responsibilities
19
5
Arrangements
19
1. Overview.
This Appendix is in addition to the PAT Procedure and Guidance, and focuses only on
potentially sensitive electrical equipment in Laboratory’s, Workshops, LAN room, etc.
Legislation requires that all electrical equipment in use shall be
constructed, maintained and used in such a manner so as to
prevent danger. This is absolute: no matter what time or cost
involved, it must be done.
The above requirement includes potentially sensitive electrical
equipment that could cause injury. This applies even if it is for
example: unique, high value, temporary, in use 24/7,
inaccessible, etc.
Fig 1: All electrical equipment
shall be: ‘constructed,
maintained and used so as to
prevent danger’.
Legislation does not specify what to do, or how frequently. This
allows risk-based controls appropriate to the risk rather than a
rigid test regime. In practical terms the safety of persons using
and maintaining the equipment must be ensured, but without
any unnecessary or intrusive maintenance.
2. Purpose.
Whilst most electrical equipment in use today suffer no adverse effect during routine
combined inspection and test, particularly sensitive equipment are vulnerable.
The first element of the PAT process - formal visual inspection - is relatively non-invasive.
However, the recommended polarity, earth continuity and insulation resistance tests, if
applied indiscriminately can expose sensitive equipment to damaging current and voltage
levels.
Because damage to sensitive equipment is possible, this Appendix 5 clarifies the minimum
level of test and inspection necessary for such equipment, and the importance of maintaining
records to evidence this.
Note: Specialised electrical equipment may require inspection and test by a person with specific
competence on that type of equipment, e.g. the original manufacturer, or their authorised service and
repair agent, or a reputable servicing company that deals with that type of equipment.
Page 17 of 25
3. Scope.
This Appendix 5 covers the combined inspection and test of potentially sensitive electrical
equipment typically found in laboratory, workshop, LAN room, etc., in particular it applies to:



Potentially sensitive electrical equipment used for teaching and/or research.
As above where more than one item is connected/considered as a single apparatus.
As above for equipment supplied pre-assembled, or ready fixed in racking or similar.
Often overlooked are 230V power supply cables,
(various types e.g. IEC lead, Figure 8, Cloverleaf, etc.),
however Class I equipment relies on its 230V power
lead for the ‘protective’ earth, and possibly also a
‘functional’ earth. Correct polarity may also be vital, via
the appropriate connection. These leads are easily
damaged under heavy equipment, sharp edges, hot
surfaces, etc., so careful visual examination is required
along each cable and plug top.
Fig 2: Multiple IEC power leads
Power pack, PSU’s or similar: The 230V mains input is
in scope, but not any reduced output ˂50 volts AC.
4. Definitions.
(The following are extracts from the full ‘Definitions’ list, and are particularly relevant to this Appendix).
 Potentially sensitive electrical equipment: Equipment considered potentially at risk
of damage if subject to standard PAT. (Note: such equipment does not necessarily
also have to be unique, or have a high intrinsic value, etc.).
 Protective Earth (PE): A low impedance path that ensures all exposed conductive
surfaces remain at the same electrical potential as the Earth, (to avoid persons using
the equipment receiving an electric shock if a fault has occurred). Not expected to
carry any current except under fault conditions.
 Functional earth (FE): A separate low impedance path to enhance the operation of
the equipment, (interference suppression, surge protection, common reference point,
etc.). Not form part of any protective earth, sometimes called ‘clean earth’. Expected to
carry current under normal operating conditions.
 User checks: Prior to each use, the user is required to carry out a series of simple
visual checks on the equipment. In practice these take very little time and ensure any
obvious damage or deterioration are identified. See Appendix 2 for further detail.
 Formal visual inspection (recorded): Over time all electrical and mechanical
equipment require some form of preventative maintenance, over and above the basic
user checks. A significant majority of related problems are identified via this quick,
recorded process. See Appendix 3 for detail.
 Combined inspection and test (recorded): Whilst visual inspection identifies most
safety related issues, when combined with formal testing hidden faults are identified,
(i.e. using calibrated test equipment). See Appendix 4 for further detail.
Page 18 of 25
5. Responsibilities.
(The following are key responsibilities from page 5 of the full PAT Procedure and Guidance).
5.1
Equipment ‘owner’, (for example PI, Lab manager, primary user or equivalent)
 Before any inspection and test, the owner, or primary user of the sensitive equipment
under test shall be responsible for clear identification of the full extent of the
equipment, (it may span several connected items). All potentially hazardous power
supplies and data connections shall be identified and isolated.
 Ensure that no equipment power supply can accidently or automatically re-energise
whilst it undergoes a routine inspection and test.
5.2
Competent person carrying out the combined inspection and test
 Before commencing a test sequence, the competent person shall liaise with the
equipment owner, or primary user, to verify the correct equipment, and ensure all
potentially hazardous power or data connections are correctly isolated/made safe.
 Once identified, label individual power supply cables, power packs, etc., to assist its
future test and maintenance. The competent person carrying out the test then in effect
becomes a ‘duty holder’ for the short period that they are in control of the apparatus.
Note: It must not be assumed that persons carrying out an inspection and test would readily
recognise potentially sensitive equipment, amongst other electrical apparatus.
Clear identification is required therefore of all such equipment before an inspection and test,
particularly if the equipment is partly concealed within racking or under a workbench, etc.
6. Arrangements
6.1
Types of PAT equipment
For the purposes of this Appendix, hand-held PAT appliances are considered in 2 groups:
1.
Basic level PAT appliance. Typically easy to operate, automating the process to
factory-set values: suitable for most PAT inspection and tests at University.
However, the PAT appliance cannot distinguish a potentially sensitive item, so may
subject the earth continuity path to 1.5 times the fuse rating for up to 20 seconds, and
insulation resistance to around 500 Volts, (local instrument Manual will confirm these).
The equipment under test may be at risk if output from the PAT test instrument exceeds
the design parameters of the equipment under test. Helpful data may be available from
suppliers/manufacturers, but is less likely for older/obsolete equipment.
2.
Advanced PAT appliance. These offer additional test
facilities, (sometimes called ‘soft test’ options), such as low
current earth continuity measurement. A ‘soft’ test is
significantly less aggressive than a standard test, hence is
ideal for sensitive equipment. However, soft tests only
simulate fault conditions so their use should be limited to
instances justified by dynamic risk assessment.
Rather than use default settings, user defined test
sequences for sensitive equipment may be stored in PAT Fig 3: An example high-end
PAT device: many offer a wide
equipment memory.
range of tests.
Page 19 of 25
6.2
‘Generic’ PAT Risk Assessment
The process of risk assessment underlies safe provision, use and maintenance of portable
electrical equipment. For most non-sensitive items, (e.g. centrifuge, microscope, autoclave),
individual PAT risk assessments are not required: to avoid duplication, group these under a
single ‘generic’ risk assessment. The stages are broadly the same for any risk assessment:
1.
Identify the
significant
hazards from
the equipment
2.
Decide who
could be
harmed,
and how
3.
Evaluate the
risk and decide
on necessary
precautions
4.
Record the
findings, and
implement them
5.
Review and
update the risk
assessment as
necessary
A generic PAT risk assessment would consider common/typical hazards, for example:
 Local environment
 Slips and trips
 Adjacent equipment
 Electric shock
 Manual handling
 Lone working, etc.
A generic PAT risk assessment identifies the broad range of control measures necessary for
that group of similar electrical equipment - the assessment would be suitable and sufficient,
but of a ‘generic’ nature.
6.3 ‘Dynamic’ PAT Risk Assessment.
The above generic approach is suitable for most electrical equipment in an office,
Residence, Lab, Workshop, LT, etc. However, if sensitive electrical equipment presents
unique hazards, then dynamically tailor controls necessary for those hazards.
For example, typical hazards to look for during a dynamic risk assessment include:
 Trained, competent tester
 Unfamiliar equipment
 No access behind equip’
 Limited time (stress)
 Exposed (live) terminals
 Fragile/delicate equipment
 No manufacturers literature
 Secondary power supplies
 Safety of persons nearby
 Pressurised vessel near
 Piped liquids/gasses
 Insufficient lighting, etc.
A dynamic PAT risk assessment may conclude it would not be safe to continue with the
standard inspection and test for a particular piece of equipment. In essence:
A 'generic' risk
assessment
considers common
hazards & controls.
Each item then has
a brief on-site
'dynamic' risk
assessment.
Outcome: either it is
safe to continue with
a full combined
inspection and test...
.. or full sequence is
not safe, and a
reduced inspection &
test is necessary.
A formal visual inspection is necessary for all electrical equipment that may present danger.
However, if standard earth continuity and insulation tests could then potentially cause harm,
(to persons or equipment), options A, B or C below should be considered/justified:
Page 20 of 25
To summarise: a proportionate approach would therefore be:
1.
Identify any
equipment
potentially at risk
from full PAT
tests.
2.
With users
permission, fully
isolate power
and data from
the equipment.
3.
Conduct (and
record), a formal
visual inspection
only at this time.
4.
Conduct a
dynamic RA to
determine
appropriate
electrical tests.
5.
After tests,
reconnect but
re-energise the
equipment only
with permission.
Fig 4: Summary approach
A ‘dynamic’ PAT risk assessment thus focuses on safe provision, use and maintenance of
each item of sensitive electrical equipment - but taking account of local hazards and not
introducing unnecessary or intrusive maintenance.
The following paragraphs clarify test options in detail.
Page 21 of 25
6.4
Formal visual inspection (recorded).
Formal visual inspection of potentially sensitive electrical equipment is the default position.
Whilst it is to be as non-intrusive as possible, to be thorough the equipment must be fully
isolated from all power supplies to enable the plug top to be opened, (unless of the moulded
type), and its connections and fuse rating checked.
The formal visual inspection process is:
Confirm
equipment.
Fully isolate.
Seek help if
unsure.
Complete
without
moving the
equipment if
possible.
Record a
brief
description,
model, type,
etc.
Undo/check
plug, cord(s),
and covers
for any signs
of damage
Note any
concerns,
repair or
advise as
necessary.
Regarding the following electrical tests, it is important to disconnect all connecting network
cables etc. before testing, to avoid a false reading.
However, this may not be possible for various reasons, and requires the direct
permission/assistance of the PI, Lab manager, primary user, etc.
6.5
Earth continuity test. RPE. Class I equipment only.
Summary:

Option A: Low current, (soft) test: to avoid damaging sensitive equipment, a 6 volt,
200 mA maximum test may be used to measure earth continuity resistance, but not
its integrity. Likely to be an option from an advanced PAT test device only.

Option B: Continuity tester: with open circuit voltage of ˂100mV, and short circuit
current of ˂100mA. Able to reliably measure resistance of 0.1Ω to 10% accuracy.

The standard option, not recommended for sensitive equipment, is high current (up to
1.5 times plug top fuse rating), to simulate a fault current through the earth path.
In detail:
Class I equipment requires an effective, low resistance earth path from the earth pin in the
mains plug of the equipment, along the power supply cord, to the equipment casing. If that
earth connection fails, and an electrical fault develops within the equipment, persons
touching it may receive an electric shock.
The mains lead earth conductor terminates inside Class I equipment at an earth terminal.
The resistance between this earth terminal, and any exposed metal casing, should not be
more than 0.1 (diagram below).
However, this earth terminal may not be accessible, so an acceptable alternative is to
measure earth continuity from outside: i.e. from mains plug earth pin, along the supply lead,
to the equipment metal casing, (where such metal casing exists).
Page 22 of 25
Metal casing
L
N
E
Appliance
Supply cord
Resistance from the internal earth terminal,
to metal casing, to be ˂0.1 ohms. To avoid
removing any casing, it is acceptable to
measure this path externally instead, from
plug top earth pin, to metal outer casing.
Options for potentially sensitive electrical equipment are therefore:
 Option A: Measure the full earth continuity path using an advanced PAT test device,
set to deliver 6 volt, 200 mA maximum.
 Option B: Measure full earth continuity path with suitable continuity tester connected
between 13A plug earth pin, and any suitable earthed point on the equipment casing.
Even with Class I equipment it may not be possible to establish earth continuity from the
appliance 13A plug earth pin to a point on the equipment outer casing. Exposed metal or
screws may not connect to earth, or be shrouded in paint, plastic, insulation, etc. This may
be by design, and is no reason to fail the equipment - if persons cannot touch earthed metal,
they cannot receive an electric shock if that metal becomes live. Record any such lack of
connection.
Notes: 1). Subtract the resistance of the mains lead itself if the earth continuity reading indicates
above 0.1, (i.e. a ‘fail’). The resistance value of the mains lead is available from tables within the
User Manual, or manufacturer’s websites. Contact OSHEU for further explanation if necessary.
2). Functional earth: It is very important that functional earthing is not subject to a ‘hard’ test. If
missing, there is no reduction in safety. Do not attempt to establish an earth connection from any
external signal sockets, seek advice of equipment Primary User if unsure.
6.6
Insulation Resistance test. RISO
Summary:

Option C: Reduced voltage (soft test): To avoid sensitive equipment damage,
select a lower 230V insulation test. Limited to mains voltage, this is useful for testing
equipment that may be, for example: surge-protected, polarized, containing
microprocessors, sensitive to static, or any that would otherwise fail a standard test,
etc.

Routinely measured at 500V dc, 2-3 mA. Not recommended for older IT and sensitive
electronic equipment, (but ok if constructed to BS EN 60950 standards).
In detail:
For Class I & Class II equipment, the Insulation Resistance test identifies any breakdown of
insulation between the protective earth, and live and neutral parts of the equipment and its
lead. Routinely measured at 500V dc, 2-3 mA, it possibly places at risk sensitive electrical
equipment, (but not that built to BS EN 60950 standards).
Also, when tested at 500V equipment with filter networks connected across line and earth
may give false readings likely to ‘fail’ a test. Therefore a less onerous approach is required:
the alternative reduced voltage of 230V, (i.e. the soft test option).
Page 23 of 25
Advanced PAT equipment uses 230V to measure the leakage current across the insulation,
typically limited to 2-3 mA. Equipment that normally operates at 230V supply voltage would
therefore not be exposed to any detrimental effect from this setting.
For Class II equipment, if the equipment is all insulated, (no exposed metal parts), no
insulation resistance test is necessary.
No insulation is perfect and there is always an amount of leakage, even if nominal.
6.7
Alternative tests.
For completeness the following may be offered by advanced PAT test instruments. However,
these are not recommended as explained below:

Protective Conductor Current measurement, (previously ‘Earth Leakage’ test).
An alternative to Insulation Resistance, (if that test could damage the equipment).
Not recommended because the test is run at full load under mains power, via the
PAT instrument, and any current flowing to earth is measured.

6.8
Alternative or Substitute Leakage Current (soft test): A substitute on advanced
PAT devices, (40V ac, 50Hz, 20 mA maximum). This voltage will not power up or
harm the appliance. Readings scaled up to represent mains voltage, however filter
suppression capacitors can give substantially inaccurate readings. Class II only.
Justify reduced tests.
The accepted way to maintain portable electrical equipment, in order to prevent danger, is to
verify the equipment polarity, earth continuity, and insulation resistance. A School or Division
is free to take an alternative approach, however robust evidence must be in place to justify
and support this.
The following flow chart offers a measured, risk-based approach to the reduced inspection
and tests offered earlier.
6.9
Frequency of inspection and testing:
Legislation does not specify how frequently an inspection and test is required, thus allowing
risk-based controls appropriate to the risk rather than a rigid test regime.
A dynamic risk assessment of each item of potentially sensitive equipment guides the
School / Division to an appropriate inspection and test frequency. Ultimately, deciding the
frequency is a matter of judgement by the School / Division.
However, for operational reasons it may be extremely difficult/disruptive/costly to fully power
down sensitive electrical equipment for an inspection and test. Where this occurs, log the
formal visual inspection, and set an appropriate date for a combined inspection and test as
necessary.
Examples include: during annual planned maintenance, or when local remedial action takes
place, or when rack-mounted equipment is moved, or when testing the local emergency
response/contingency plan, etc.
Over a number of inspection cycles it may be possible to extend the inspection and test
period for potentially sensitive electrical equipment.
Page 24 of 25
Appendix 6: Example applications:
Scenario 1:
The School / Department has trained staff who are able to carry out formal visual
inspections, and combined inspection and testing.
In this case the School / Department can arrive at their own appropriate frequency of
inspection and test, based on risk assessment, but in line with:

the 7 Risk Factors as detailed in Table 1, (PAT procedure, page 8), and

the minimum expectations as detailed in Table 2. (page 10 of PAT Procedure), or
As test records accumulate, the above inspection and test frequency may be shortened or
extended accordingly.
Scenario 2:
The School / Department does not have has trained staff who are able to carry out formal
visual inspections, and combined inspection and testing.
In this case it is likely that the School / Department will need to use external contractors to
carry out the combined inspection and testing.
As test evidence builds up in support, it may be possible to extend the frequency of
combined inspection and testing, to that of Table 2.
This will ensure that the requirements for formal visual inspection, and combined inspection
and testing are carried out in a cost effective way.
Scenario 3:
The School / Department has trained staff who are able to carry out formal visual
inspections, and combined inspection and testing, but there is a significant volume of
electrical equipment to manage.
In this case it is likely that the School / Department will need to use external contractors to
carry out the bulk of combined inspection and testing, supported by local trained staff inbetween contractor visits.
There may be scope for local trained staff carry out formal visual inspections, (only), and the
external contractors carrying out the combined inspection and tests.
Page 25 of 25