EICR code - potential load on lighting circuit more than MCB rating

[Electric Magic]

I'm writing up an EICR. On one of the lighting circuits the potential load is theoretically about 1300W on a 5A BS3871 breaker. In reality, the arrangement has been in place for at least 8 years there are no signs of thermal damage, it is difficult to find lamps these days that would max out all of the fittings (although there are those vintage and tough lamps that get around this), and they are highly unlikely to ever have all of the lamps on at once. My instinct is to give it a code 3, what would you give it?

 

[Sparkie30]

I'm writing up an EICR. On one of the lighting circuits the potential load is theoretically about 1300W on a 5A BS3871 breaker. In reality, the arrangement has been in place for at least 8 years there are no signs of thermal damage, it is difficult to find lamps these days that would max out all of the fittings (although there are those vintage and tough lamps that get around this), and they are highly unlikely to ever have all of the lamps on at once. My instinct is to give it a code 3, what would you give it?

why c3? if all tests are fine i cant see the problem.

 

[Octopus]

I wouldn't even comment on it.

Tin hat on

 

[Electric Magic]

My thinking is that when you design a lighting circuit you are supposed to do so taking into account the max wattage of the fittings being used e.g. Ib must be less than or equal to In which must be less than or equal to Iz. The I2 of the curcuit breaker will be above In and almost definitely above the potential load (so would not trip) and the manufacturer is unlikely to be in favour of the circuit breaker being subject to a level of current above the device rating under normal operating conditions (it may lead to overheating and shorten the life of the device).

 

[malcolmsanford]

Would you consider your circuit does not comply to reg 559.5.1.204?

 

[Octopus]

http://www.leghrichardson.co.uk/electricalpresentations/BS7671 17th Edition 2015 part 5.pdf

 

[andyb]

I wouldn't even comment on it.

Tin hat on

I probably wouldn't even notice it.

 

[Electric Magic]

Would you consider your circuit does not comply to reg 559.5.1.204?

No, the lampholders are still protected from overcurrent by a device that complies with that reg (provided the 5A MCB continues to work). It's the impact of up to 5.65A hypothetically running through a 5A MCB that I was wondering about. Perhaps I just need to apply a bit of engineering judgement and conclude that due to the current ban on regular incandescent lamps and diversity its not worth giving this a code...

 

[davesparks]

If the potential load is theoretically 1300W then what is the actual, non theoretical load at the time you carried out the inspection?
Did you apply any diversity to the load or just count the number of lights?
What sort of environment is this in? What are the lights and how are they controlled?
If it's an office with 1300W of lights which is all switched on at once and stay on for the whole day then it's different to the lights in a house.

 

[malcolmsanford]

I haven't got my OSG on me but I believe that the guide recommends a maximum of 10 lights on a domestic circuit, is this a domestic circuit? And remember your test to the 7671 not a guide.

I can see where your coming from, but remember your protection device is really protecting the cable, not how many lights you have on a circuit. If you have a 1.0mm/1.5mm cable then unless it is seriously degraded by rating factors it will quite happily run on that 5 amp MCB.

Also remember you can have unlimited sockets on a RFC under 90m2 and you theoretically can plug 30 3 kw fires into it, but the PD will soon trip.

It is the same as your lights. You can have as many lights as you like on your circuit but eventually you will overload it and that 5 amp MCB will trip before there is damage to the cable.

For me it would be no code