Emergency Lighting, Dedicated Circuit Advise Please.

[jktelectrical]

Hi

I have recently carried out an electrical installation in a small office unit that will be occupied by the public and around 5-10 office staff its a showroom

I have installed non maintained emergency bulkheads within the property and exiting signs on the exit positions

The problem I have is that a contractor has been in to carry out extra installation works within the office

The contractor has told the client that the emergency lighting should be on its own dedicated circuit form the distribution board

The way I have wired the emergency lights is that I have taken a 1.5mm twin and earth from the distribution board to a a switch then from the switch I have wired the general lights as a switch feed from the switch then the emergency bulkheads have been feed using a 3 core and earth via a double pole key switch from the main switch position

I would like a quote from BS5266 if possible, I do have a copy but I am unable to gain access to it at the time being

Thanks

 

[nickblake]

Well that how i'd have wired it to its all very well installing on own dedicated circuit but if the power fails on the lighting circuit then there is no emergency lighting in that area and will only work if there is a general power power cut i will look up in the regs see what it says

 

[sparx24]

I believe either method is allowed but your way is imho the best for the reason given by nickblake.
I have had some 'discussions' over this with LABC in the past who wanted it seperately fed as they did for smoke detectors, they are now 'enlightened' as to the disadvantages of being able to turn off a circuit and still have lights working!

 

[sparx24]

further; regs section56 relate to escape lighting as well as fire circuits but 360.9 merely refers to BS5266;
reading the ICEL guide to which the only reference to supplies seems to be appendix B compliance tick list which asks in 2.7
"Are non maintained luminaires monitoring the local lighting circuit?"
Good enough for me!

Source ref: ICEL 1006:Emergency lighting design guide February 2008
(free downloadable)

 

[accordfire]

Hi

I have recently carried out an electrical installation in a small office unit that will be occupied by the public and around 5-10 office staff its a showroom

I have installed non maintained emergency bulkheads within the property and exiting signs on the exit positions

The problem I have is that a contractor has been in to carry out extra installation works within the office

The contractor has told the client that the emergency lighting should be on its own dedicated circuit form the distribution board

The way I have wired the emergency lights is that I have taken a 1.5mm twin and earth from the distribution board to a a switch then from the switch I have wired the general lights as a switch feed from the switch then the emergency bulkheads have been feed using a 3 core and earth via a double pole key switch from the main switch position

I would like a quote from BS5266 if possible, I do have a copy but I am unable to gain access to it at the time being

Thanks

The contractor is talking out of a hole which doesn't reside in his cranium.

Okay, Emergency Lighting 101. The WHOLE point of emergency lighting is that it operates upon failure of the LOCAL lighting circuit.

This is because it is considered dangerous, in the event of a fire, for people to be wondering around, in a panic, in the dark.

That people, qualified people, don't get this, amazes me.

Your system is fine - it's all fed from the same supply - and hence, if the local lighting circuit fails, the non-maintained fittings will illuminate.

What your contractor is proposing would require the entire electrical supply to fail. He deserves a dummy of the day award!

From memory, it's BS5266-1 Clause 6.

The specific requirement is to ensure operation of the emergency lighting in the event of failure of the local cub-circuit.

Where the confusion arises, is the old standard (1999), used to state that an independent supply was needed to ensure the supply to the emergency lighting was not interrupted. Talk about ambiguous.

What it means is that the SWITCHED feed for the primary lighting must not interfere with the supply to the emergency lighting luminaries.

However, unless you're employing some kind of sub-circuit monitoring in your system, such that you can tell electrically that a lighting circuit has failed, there's no way of complying with the standard unless it is connected to the same local supply. Normally, this kind of monitoring is only ever found on central battery systems, where several zones of lighting are fed from one point.

 

[telectrix]

i don't do much in the way of em. lighting, just when it forms part of an install, but i always feed from local lighting circuit, so as if the supply to that circuit fails, the em's activate. i only install keyswitches if it would cause problems by turning off the lights to test.

 

[Tillywolves]

Should be wired into local lighting circuit, and test points provided.

 

[tonys]

extract from section 6.2 Failure of normal supply to part of a premises

Except in the case of a maintained system, it is normally necessary to ensure that the emergency lighting is provided in the event of the normal supply subcircuit failure in particular areas.

 

[WDMDL]

Just a thought... if you did provide a separate circuit, because you need to monitor the local lighting circuit, you would be borrowing a Neutral. Which is obviously not good.

Simon.

 

[lamb]

You could monitor the local circuit with a din rail contactor (N/O) next to the MCBs, the coil is fed from local lighting cct, the contacts feed EM lights.

 

[accordfire]

You could monitor the local circuit with a din rail contactor (N/O) next to the MCBs, the coil is fed from local lighting cct, the contacts feed EM lights.

Normally the way it is done on big open space areas, as it makes for easier maintenance, etc.

Either way, the final circuit needs to be able to monitor the local lighting final circuit for compliance with the standard, and proper operation.

 

[accordfire]

Just a thought... if you did provide a separate circuit, because you need to monitor the local lighting circuit, you would be borrowing a Neutral. Which is obviously not good.

Simon.

Um, how's that?

I've been trying to figure out what you're doing with the neutral to need to borrow one........

Separate circuit, with Live, Neutral, and earth.

Separate circuit would need a way to monitor loss of supply on the lighting feed......either through a contactor, or other voltage sensitive switching device.

What would you do with a neutral from the local lighting?

Curious.