Lighting circuit MCB size

[neil_ev]

Hi all,

if using 2.5mm can i put a 16A MCB on a lighting circuit? never needed to before so a little unsure, but can't remember of they're limited to a certain amperage.

thanks

 

[R G]

Depends on the fittings , if fittings are only wired in small guage wire then you can't.. also what are the switches rated at..

 

[neil_ev]

all fittings would be sufficient. simply wanted to know if there is a Reg. limiting the power on a lighting circuit.

 

[kingeri]

If the circuit is properly designed then go for it!

 

[jimjimjim]

Depends on the fittings , if fittings are only wired in small guage wire then you can't.. also what are the switches rated at..

I would say that if designed correctly (i.e 1 fitting at a time tapping off the 2.5), then smaller condutor size for the fitting is fine. You could design it to omit overload current. Im thinking of lighting support couplers specifically.

If you're on about going to an existing installation and just want to uprate the MCB, then you'd need to make sure the circuit is suitable to do so.

 

[R G]

As Above really , all depends on what your thinking of really, could you give a bit more info ?

 

[GLENNSPARK]

Depends on the fittings , if fittings are only wired in small guage wire then you can't.. also what are the switches rated at..

surely the gauge of the wire would be in relation to MAX current draw for the load they serve...

 

[R G]

My Thoughts are that the internal wiring within many fittings you find are quite small, with many fittings that can be connected to a circuit like this such as modular fittings have in line fuses within the fitting , I was thinking more on the lines of domestic fittings.

 

[GLENNSPARK]

My Thoughts are that the internal wiring within many fittings you find are quite small, with many fittings that can be connected to a circuit like this such as modular fittings have in line fuses within the fitting , I was thinking more on the lines of domestic fittings.

not series though are they...

 

[neil_ev]

As Above really , all depends on what your thinking of really, could you give a bit more info ?

have been asked by a farmer to put a new lighting circuit in a shed. 4 x 400W low bay metal halide fittings controlled from 1 20A switch.

 

[Raja Awais]

depends upon fittings cables and load

 

[telectrix]

you might need a C type breaker.

 

[GLENNSPARK]

have been asked by a farmer to put a new lighting circuit in a shed. 4 x 400W low bay metal halide fittings controlled from 1 20A switch.

so where have you got 16A from then?

 

[Clive P]

Hi,

What's wrong with a correctly rated 10A?

Regards.

 

[MDJ]

10 Amp C rated Breaker would be more than adequate

 

[nickblake]

To be honest i would ask my self why 16 amps that's an awful lot of lights i would look at splitting the circuits to reduce the loads rather than increase the cable and MCB size , also depending on the lights you may require a C type breaker if the lights are discharge etc

 

[guest119]

If you feel you need to, fit a spur at each light and fuse it down for the final flex.
Often done for substantial wall mounted externals.
Call it a maintenance switch.
Boydy

 

[Zebra Stripe]

Oh inrush is so under-estimated and so damn tricky to pin down

 

[Richard Burns]

If you have BC or ES lampholders you are limited to a 16A OCPD, if not then it is down to the fittings.

 

[GLENNSPARK]

If you have BC or ES lampholders you are limited to a 16A OCPD, if not then it is down to the fittings.

look its the same old story Richard...attempting to combat inrush by going for a higher I N...rather than doing the correct thing which is assessing the characteristics of this circuit & connected loads...then choosing the correct OPD to suit...