More than 1 circuit on mcb

[Wardy83]

Hi, recently carried out an eicr at a rented property. There were 5x 1mm in a 6amp mcb for lighting.. my question is what code should I be looking at for this??
I am sure I have heard someone mention or read somewhere about overpopulating an mcb should be a code 2... but then i have also heard it’s all counted as 1x circuit so all the lights to the property are on 1x circuit.. which would be a code 3 recommendation they should be split.. advice would be welcomed.

cheers

 

[radiohead]

If its fed from a single device it is one circuit. If in your professional opinion the conductors are adequately terminated and provided with fault and overload protection then no code is appropriate. There have been numerous debates here on the claims that 'multiple circuits' cannot be connected to a single device, ignoring the fact that it is multiple conductors forming one circuit, not multiple circuits. Nowhere do the regulations specifically prohibit this arrangement, nor do they require more than one lighting circuit in an installation.

 

[littlespark]

A lighting circuit is a radial with several branches off whether from a switch or looped at the light. This one is just branched from the source.

why is it like this though? Is there shared neutrals where doubling up the circuits solved the problem, or is there another damaged 6A breaker that the circuit has been moved from as a “temporary” fix.

 

[westward10]

It is five final circuits.

 

[brianmoooore]

It is ONE final circuit. A radial with five branches from the source. If there are no other issues, than it is perfectly satisfactory, and attracts no code at all.
It's also a circuit arrangement that makes fault finding easier.

 

[Baddegg]

I’d say it’s 5 radial circuits and test at the extremity of each one....they will all be different lengths, different installation methods with branch’s etc giving different readings.....

 

[westward10]

It is ONE final circuit. A radial with five branches from the source. If there are no other issues, than it is perfectly satisfactory, and attracts no code at all.
It's also a circuit arrangement that makes fault finding easier.

Five.

 

[Baddegg]

Five.

You talk to much westy ??

 

[DPG]

Doesn't the definition of a circuit mean that 2 radials from one OCPD is still defined as is one circuit?

 

[brianmoooore]

I’d say it’s 5 radial circuits and test at the extremity of each one....they will all be different lengths, different installation methods with branch’s etc giving different readings.....

You test at the extremity of each branch and record the highest, just like you would with a lighting circuit that leaves the CU on one cable, and then splits multiple ways.

 

[mattg4321]

Saying it’s more than one circuit is the same as saying a ring final with a spur from the mcb is more than one circuit.

 

[westward10]

Saying it’s more than one circuit is the same as saying a ring final with a spur from the mcb is more than one circuit.

"Final circuit".

 

[Wardy83]

It is five final circuits.

Yeh 5 final circuits in 1x 6amp mcb. Looks like they have just added to the installation over the years, but instead of upgrading board for more ways, they have just put them all in 1.

 

[westward10]

Yeh 5 final circuits in 1x 6amp mcb. Looks like they have just added to the installation over the years, but instead of upgrading board for more ways, they have just put them all in 1.

Common occurrence unfortunately.

 

[brianmoooore]

Yeh 5 final circuits in 1x 6amp mcb. Looks like they have just added to the installation over the years, but instead of upgrading board for more ways, they have just put them all in 1.

There's absolutely no problem with that, as long as the circuit isn't overloaded. Used to be a maximum of 12 lamps for a 6A MCB, but this has become irrelevant with first cfl, and now LED lamps, although inrush still has to be considered.
I would make a comment, however, if this is the only lighting circuit.

 

[DPG]

I suppose it depends if the manufacturer states the physical capacity of the MCB terminal in terms of number of conductors.

 

[brianmoooore]

I suppose it depends if the manufacturer states the physical capacity of the MCB terminal in terms of number of conductors.

They'll state the max. capacity in mm2, not the number of cables. It's unlikely that five lighting cables will reach that limit, even if the ends are doubled over.

 

[westward10]

They'll state the max. capacity in mm2, not the number of cables. It's unlikely that five lighting cables will reach that limit, even if the ends are doubled over.

Conductors not cables.

 

[Pete999]

Hi, recently carried out an eicr at a rented property. There were 5x 1mm in a 6amp mcb for lighting.. my question is what code should I be looking at for this??
I am sure I have heard someone mention or read somewhere about overpopulating an mcb should be a code 2... but then i have also heard it’s all counted as 1x circuit so all the lights to the property are on 1x circuit.. which would be a code 3 recommendation they should be split.. advice would be welcomed.

cheers

An MCB supplies a circuit, so anything connected to it is deemed a circuit regardless of how many wires there are, not an ideal situation, but seen it loads of times.

 

[littlespark]

5 conductors physically into an mcb I can see... the corresponding neutrals into one hole of the neutral bar? Don’t think so.
So the neutrals won’t match the circuit number.

So if this one circuit was one cable from the CU to a nearby joint box, which then split 5 ways.... is it 1 or 5 circuits?