Forms of Separation
BS EN 61439-2
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Forms of Separation
BS EN 61439-2
Objective
The principle reason for separating an assembly is to facilitate access to a part of the assembly
whilst other parts may remain energised and in service. Whilst, in general separation does not
improve the electrical performance of the assembly it does provide:
The Law
Electricity at work act
Legal Obligations
Regulation 14
"No person shall be engaged in any work
activity on or near any live conductor
(other than on suitably covered with
insulating material so as to prevent
danger) that danger may arise unless:
In the UK the standards do not take precedence over legal obligations in particular the Low
Voltage Directive (LVD) and the Electricity at work Act (EWA).
a) it is unreasonable in all the
circumstances for it to be dead; and
When working within a partially energised assembly, there is no allowance for tolerable risk. If
an assembly can reasonably be isolated prior to any covers being removed, it must be.
b) it is reasonable in all the circumstances
for him to be at work on or near it while
it is live; and
• Protection against contact with live parts belonging to adjacent functional units
• Protection against the passage of solid foreign bodies from one unit of an assembly to an
adjacent unit.
Where it is impractical to totally isolate an assembly the degree of separation, and the way in
which the separation is achieved within the assembly should be considered in a risk assessment
by the Duty Holder. This risk assessment will consider all relevant factors including:
i)
ii)
iii)
iv)
Work to be carried out
Mechanical protection afforded by any insulation and separation
Possibility of initiating a flashover
Likelihood of an electric shock
c) suitable precautions (including where
necessary the provision of suitable
protective equiment) are taken to
prevent injury.
BS EN 61439-2 stipulates:
Power Switchgear and Controlgear assemblies can be divided to meet one or both of the
following conditions between functional units, separate compartments or enclosed protected
spaces.
1. Protection against contact with hazardous parts. The degree of protection shall be at least
IPXXB
2. Protection against the passage of solid foreign bodies. The degree of protection shall be at
least IP2X
The form of separation shall be the subject of an agreement between manufacturer and the
end user.
BS EN 61439-2 includes four main categories of separation (1,2,3,4)
The annex offers a guide to the various types of construction. It identifies a total of 18 variants
with the introduction of two sub categories ‘Compartmentalised’ and ‘Group Mounted’.
Installation criteria
Isolation available for all operations (except changing fuse links)
Adjust settings, limited maintenance, while adjacent circuits live
Connect / disconnect cables, adjust settings, limited maintenance,
while adjacent circuits live
Recommended form
Form 1 or 2
Form 3
Form 4
1
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No Internal Separation.
Isolation available for all operations (except changing fuse links).
Form 1
Form 1 or 2
Form 1
Forms of
Separation
Form 2a
Separation of busbars from
functional units, the housing of the
device is the means of separation.
Form 3a
Group Mounted
Form 3b type 1
Group Mounted
Form 3b type 1
Compartmentalised
Separation of busbars from functional units and
separation of functional units from each other.
Terminals are separated from functional units
but not from each other. The housing of the
device is the means of separation.
Separation of busbars from functional units and separation of functional units from each
other. Terminals are separated from functional units but not from each other.
2
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Form 3b type 2
Compartmentalised
Separation of busbars from functional units and separation of functional units
from each other. Terminals are separated from functional units and busbars
but not from each other.
Isolation available for all operations (except changing fuse links).
Form 3b type 2
Group Mounted
Form 1 or 2
Separation of busbars from functional
units.
Adjust settings and limited maintenance, while adjacent circuits live.
Separation of busbars from functional
units, the housing of the device is the
means of separation.
Form 3
Form 2b type 2
Form 2
Form 2b type 1
Form 3
Forms of
Separation
3
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Forms of
Separation
Form 4a type1
Group mounted
Form 4a type1
Compartmentalised
Separation of busbars from functional units and separation of functional units from each
other. Terminals are separated from other terminals and from the busbars.
Form 4b type 5
Separation of busbars from functional units
and separation of functional units from
each other. Terminals are separated from
their own functional unit, other terminals
and from the busbars. Separation of
terminals by insulated coverings.
Form 4b type 6
Compartmentalised
Form 4a type2
Separation of busbars from functional
units and separation of functional units
from each other. Terminals are
separated from other terminals and
from the busbars.
Form 4b type 6
Group mounted
Separation of busbars from functional units and separation of functional units from each
other. Terminals are separated from their own functional unit, other terminals and from
the busbars.
4
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Separation of busbars from functional
units and separation of functional units
from each other. Terminals are separated
from other terminals and from the
busbars. Individual, integral glanding for
each circuit.
Separation of busbars from functional
units and separation of functional units
from each other. Terminals are separated
from their own functional unit, other
terminals and from the busbars.
Form 4b type7
Separation of busbars from functional units and separation of functional units from each
other. Terminals are separated from their own functional unit, other terminals and from the
busbars. Individual, integral glanding for each circuit.
Connect / disconnect cables, adjust settings and limited maintenance, while adjacent circuits live.
Form 4b type 4
Form 4
Form 4a type3
Form 4
Forms of
Separation
5
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Contact Us
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www.dormansmithswitchgear.com
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Dubai
U.A.E.
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Fax: 00971 4 3470002
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www.dormansmithswitchgear.com
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Forms of Separation BS EN 61439-2 2014
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