HES - training
Electrical installations & equipment
Lecturer: Ted Bernhardsen
(Prepared by: Randulf Pedersen)
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Regulations for electrical
low voltage installations
Forskrift om Elektriske Lavspenningsanlegg (FEL)
§ 12 Verification. Declaration of Conformity.
Documentation. (Sections)
Before a new electrical installation is taken into operation,
and after any modification, the responsible for the
implementation or the modification shall verify that it is
checked and tested to ensure that it meets the requirements
of this regulation.
Declaration of Conformity and documentation shall be
handed over to the owner of the installation.
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Regulations for electrical
low voltage installations
Forskrifter om Elektriske Lavspenningsanlegg (FEL)
§ 16 Planning and risk evaluation
Electrical installations shall be planned and carried out in
such a way that humans, domestic animals and properties
are protected against danger and damage under normal
operation, and such that the installations are suitable for the
intended use.
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Definitions
Protective conductor
Common description for protective conductors are, PE-conductor, equalizing wire,
equipotential bonding. Colour: yellow/green.
Direct contact
A direct contact with or touch on a live part (live under voltage).
Indirect contact
When a person touches an exposed conductive part which has become live due to
flashover caused by insulation failure between live wires and enclosure or sheating.
Extraneous conductive part
A conductive part that does not constitute any part of the electrical installation that can
reach another potential, normally earth potential.
Exposed conductive part
A conductive part of any electrical equipment that is easily touchable, and may
become live under voltage (flashover) if the equipment has a defect.
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Isolation/switching-off
Isolation (disconnecting):
Safety function designed to make the whole installation
or parts of it potential free by separating the whole
installation or parts of it from any electrical source.
Switching-off (for mechanical maintenance):
An operation that, to avoid other danger than caused
by electrical shock or electric arc, de-energize one or
more of the equipment when non-electrical work is
carried out.
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Contact dangers
Conductive parts
Exposed
conductive part
Equipotential
bonding
Protective earth
wire
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Extraneous
conductive part
Contact dangers
Indirect contact
Indirect
contact
Extraneous conductive part
Exposed
conductive
part
Contact voltage
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Indirect contact
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Contact dangers
Direct contact
Direct contact
with live wire
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Direct contact
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Duration of current flow
Impact of electric current
through the human body
Body current
The relation between body current and the duration of exposure
is crucial for the consequences on the human body.
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Protection against electrical shock
Types:
z
Automatic warning (applies to existing IT-grids)
z
Automatic isolation of the faulty circuit
z
Use of PE-wires (earthing and protective conductors)
z
Use of equipotential bonding
z
Double insulation
z
SELV/PELV (use of isolating transformer/safety power supply)
(Safety Extra Low Voltage/Protective Extra Low Voltage)
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Voltages (V)
Different power supplies:
In a laboratory several types of power supplies are available:
z 400/230 V TN-S (AC). This is the mains voltage at UiTø.
This means that 400 V 3P and 230 V P+N are available.
z 230 V AC priority (powered from a diesel generator)
z 230 V AC uninterruptible (powered from a central UPS)
z 24 V DC
z Other voltages
There are no unique labelling of different voltages as of today.
Look for signs at the voltage outlet.
PLEASE NOTE!
Always check the ratings of the power supply before
connecting any equipment.
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Extension leads
Regulations
According to regulations it is allowed to use extension leads.
Recommendation
According to HES it is recommended to reduce the use of
extension leads to a minimum to avoid:
z Fire hazard (contact faults, overload, etc.)
z Danger of creating tripwires (loose winding cables)
z Environmental disadvantages (complicating cleaning etc.)
Types of extension leads
Extension leads for use in a laboratory shall have earthed
plugs and sockets, and the cables shall always include the
PE-wire (Yellow/green protective conductor).
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Extension leads
Before use:
z
z
Check that you are using a correct extension lead
according to power requirement (Equipment to be
connected).
Check that the extension lead is in good condition!
• Plug/socket not burned, damaged or broken?
• Cable is undamaged?
• Chord anchorages are intact?
• General condition is clean and not dirty/filthy?
If all points are OK, the extension lead may be used!
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Extension leads
Under use:
z
z
z
Keep order.
Never keep extension leads, in
heaps on the floor, or on tables and benches.
When using an extension lead on a reel it shall
always be completely unwinded before use.
Always check that the extension lead is OK!
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Extension leads
After use/finished work:
z
z
Disconnecting the extension lead is done by pulling the
plug with a firm grip.
Do not pull on the cable
Coil up the extension lead after use and keep it on a safe
place.
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Fixed installations
z
Equipment shall only be connected to grounded
electric outlets.
z
Do not connect anything if the electric outlet is
loose.
z
Do not connect anything if the electric outlet has
visible burn marks, where the plug is inserted.
z
Do not connect anything if the cover on the electric
outlet is broken or dirty.
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Equipment
z
z
z
z
z
Broken or defect equipment shall not be connected.
Clean the equipment before you connect it if it is dirty
(use suitable detergents).
Do not use equipment in close proximity of volatile
gases to prevent inflammation.
Check that the equipment tolerates the exposed
operating temperatures. Check that the equipment is not
exposed to intense heat. Provide necessary cooling.
Equipment should as a minimum be checked once each
year for defects or electrical failures.
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The use of power supplies
z
z
z
Power supplies must never be connected until after the
rest of the electrical circuit is connected.
When recoupling, disconnect the power supply before
the recoupling takes place.
If you in no way can avoid to work (recouple/change)
with the power supply connected and switched ON,
please note the following:
Do never touch live parts directly.
Do never touch different exposed parts, or
exposed parts and ground simultaneously!
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If accident occurs?
REMOVE THE PERSON INVOLVED
FROM THE POWER SOURCE
z
•
•
•
Disconnect power.
Pull the person loose by gripping the clothes.
Prevent yourself from electrical shock.
z
CONTACT EMERGENCY WARD
z
START REVIVAL IF NESCESARRY
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Summary on electrical safety
Make sure that equipment is earthed in accordance with
regulations.
Check extension leads, fixed installations and equipment.
z
z
•
•
•
Damaged equipment or cables must not be used.
Burned/broken or damaged plugs/socket outlets shall immediately be
replaced.
Do not pull on the cable to disconnect any equipment from an
electrical outlet. Pull with a firm grip on the plug.
If possible avoid the use of extension leads.
Check current type and voltage before connecting equipment.
Avoid direct contact with live parts.
If accident occurs:
•
•
•
•
•
Remove/loosen person, contact emergency ward, start revival.
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