Question about emergency lighting circuits

[The Dentist]

Hi not really a DIY question, but have recently had a PIR done where I work and the tester has picked up on us having more than one circuit in a MCB, quoting ref 314.4 as the non compliant

The actual circuit is a lighting ciruit which has intermittent (one in every 4)maintained emergency units, the secondary wire in the MCB is the non switched live feed for the emegency units

I would have thought that having the Em-live on a separate mcb may cause confusion during isolation for maintenance etc, as there would be two live feeds to isolate rather than one

What would be considerd good practice in this situation? and is there anything in the regs about this?

Many thanks

 

[VanSolo]

Nothing wrong with a circuit set up like this.
314.4 does not apply, they are part of the same circuit.
Get another tester.

 

[The Dentist]

Thanks, I will have a chat to the tester, maybe he didnt realise there were Em units in the instalation

 

[ColJack]

are they stand alond EM's or integrated into the normal fittings?
if they are integrated then the tester is wrong, if they are stand alone then they can go on their own circuit..

does the permanent live wire have a keyswitch in it somewhere for testing?

normal way is one wire from the breaker to the switch where the perm live is through the keyswitch and the switched live through the normal switches..

 

[The Dentist]

They are integral with the standard units, every 4th one has the extra unswitched live to an emergency unit to charge the batteries, and activate if power fails, there is no test facility, other than switching the circuit off at the breaker to see if they remain on

 

[ColJack]

ah that might need sorting then..
you should test every few months and unless you want to sit in a dark office after hours for 3 hours then a keyswitch to turn off the EM ones only is advised..

 

[The Dentist]

Good point, never thought of that

But in general, the twin circuit in the MCB in this situation is acceptable is it?

 

[electronicsuk]

Good point, never thought of that

But in general, the twin circuit in the MCB in this situation is acceptable is it?

Definitely.

 

[ColJack]

yeah no problems with it..
a radial circuit can have branches off it anywhere, and that includes the MCB..
providing that the lights are all on the same breaker ( every 4th suggests that the office is not on a 3 phase supply? or it would be every 3rd maybe? )

 

[SUNRAY]

They should be on the same MCB, if not the lighting cct may trip and em fittings would not come on.