Forms of SeparationBS EN 61439-2

O V E R 1 3 0 Y E A R S O F E L E C T R I C A L E X C E L L E N C E

O V E R 1 3 0 Y E A R S O F E L E C T R I C A L E X C E L L E N C EO V E R 1 3 0 Y E A R S O F E L E C T R I C A L E X C E L L E N C E

Forms of SeparationBS EN 61439-2 Objective

The principle reason for separating an assembly is to facilitate access to a part of the assemblywhilst other parts may remain energised and in service. Whilst, in general separation does notimprove the electrical performance of the assembly it does provide:

• 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.

Legal Obligations

In the UK the standards do not take precedence over legal obligations in particular the LowVoltage Directive (LVD) and the Electricity at work Act (EWA).

When working within a partially energised assembly, there is no allowance for tolerable risk. Ifan assembly can reasonably be isolated prior to any covers being removed, it must be.

Where it is impractical to totally isolate an assembly the degree of separation, and the way inwhich the separation is achieved within the assembly should be considered in a risk assessmentby the Duty Holder. This risk assessment will consider all relevant factors including:

i) Work to be carried outii) Mechanical protection afforded by any insulation and separationiii) Possibility of initiating a flashoveriv) Likelihood of an electric shock

BS EN 61439-2 stipulates:

Power Switchgear and Controlgear assemblies can be divided to meet one or both of thefollowing conditions between functional units, separate compartments or enclosed protectedspaces.

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 theend 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 variantswith the introduction of two sub categories ‘Compartmentalised’ and ‘Group Mounted’.

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The LawElectricity at work act

Regulation 14"No person shall be engaged in any workactivity on or near any live conductor(other than on suitably covered withinsulating material so as to preventdanger) that danger may arise unless:

a) it is unreasonable in all thecircumstances for it to be dead; and

b) it is reasonable in all the circumstancesfor him to be at work on or near it whileit is live; and

c) suitable precautions (including wherenecessary the provision of suitableprotective equiment) are taken toprevent injury.

Installation criteria Recommended formIsolation available for all operations (except changing fuse links) Form 1 or 2Adjust settings, limited maintenance, while adjacent circuits live Form 3Connect / disconnect cables, adjust settings, limited maintenance,while adjacent circuits live

Form 4

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Forms ofSeparation

Form

1Fo

rm 1

or 2

Isol

atio

n av

aila

ble

for a

ll op

erat

ions

(exc

ept

chan

ging

fuse

link

s).

Form 2a

Separation of busbars fromfunctional units, the housing of thedevice is the means of separation.

Form 1

No Internal Separation.

Form 3aGroup Mounted

Separation of busbars from functional units andseparation of functional units from each other.Terminals are separated from functional unitsbut not from each other. The housing of thedevice is the means of separation.

Form 3b type 1Group Mounted

Separation of busbars from functional units and separation of functional units from eachother. Terminals are separated from functional units but not from each other.

Form 3b type 1Compartmentalised

2

3

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Forms ofSeparation

Form

2Fo

rm 1

or 2

Isol

atio

n av

aila

ble

for a

ll op

erat

ions

(exc

ept

chan

ging

fuse

link

s).

Form

3Fo

rm 3

Adj

ust

sett

ings

and

lim

ited

mai

nten

ance

, whi

le a

djac

ent

circ

uits

live

.

Form 2b type 2

Separation of busbars from functionalunits.

Form 2b type 1

Separation of busbars from functionalunits, the housing of the device is themeans of separation.

Form 3b type 2Group Mounted

Separation of busbars from functional units and separation of functional unitsfrom each other. Terminals are separated from functional units and busbarsbut not from each other.

Form 3b type 2Compartmentalised

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Forms ofSeparation

Form 4a type2

Separation of busbars from functionalunits and separation of functional unitsfrom each other. Terminals are separated from other terminals andfrom the busbars.

Form 4b type 5

Separation of busbars from functional unitsand separation of functional units fromeach other. Terminals are separated fromtheir own functional unit, other terminalsand from the busbars. Separation ofterminals by insulated coverings.

Form 4b type 6Compartmentalised

Separation of busbars from functional units and separation of functional units from eachother. Terminals are separated from their own functional unit, other terminals and from the busbars.

Form 4b type 6Group mounted

Form 4a type1Compartmentalised

Separation of busbars from functional units and separation of functional units from eachother. Terminals are separated from other terminals and from the busbars.

Form 4a type1 Group mounted

4

5

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Forms ofSeparation

Form

4Fo

rm 4

Con

nect

/ d

isco

nnec

t ca

bles

, adj

ust

sett

ings

and

lim

ited

mai

nten

ance

, whi

le a

djac

ent

circ

uits

live

.

Form 4b type 4

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 4a type3

Separation of busbars from functionalunits and separation of functional unitsfrom each other. Terminals are separatedfrom other terminals and from thebusbars. Individual, integral glanding foreach circuit.

Form 4b type7

Separation of busbars from functional units and separation of functional units from eachother. Terminals are separated from their own functional unit, other terminals and from thebusbars. Individual, integral glanding for each circuit.

For further information or to request one of our product catalogues please contact us from the information above. E&OA. Whilstevery effort has been made to ensure accuracy, no liability is accepted for the consequences of any error or omissions in thiscatalogue. Dorman Smith Switchgear Ltd. reserve the right to change or amend any technical specification or product detailwithout prior notification.

O V E R 1 3 0 Y E A R S O F E L E C T R I C A L E X C E L L E N C E Form

s of

Sep

arat

ion

BS E

N 6

1439

-2 2

014

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