Help with new fuse box?

[seasickstevie]

Even if there's only one RCD there should be two neutral bars, assuming it is a split board.

The lights should be on 6amp breakers. You seem be have them on 10amps.

 

[grantuk]

Many thanks for all your replies, really nice people taking time to answer my questions even as vague as the information was.

Its now been sorted, The problem was the first electrician had just put the wires into the earth and neutral in anyside. So the RCD was tripping due to the change in input and output amps? Cant explain very well but I hope you understand. Everything is now signed off, and the best part is it only cost £100


Thanks again for all your replies, I'll make sure I check around the forum and answer any questions I can in other threads.

 

[elrobbo82]

did the electrician supply you with an installation certificate for the work done? seems cheap to me to fault find, rectify and carry out the tests required to ensure the installation is safe. also surprised that another electrician has taken responsibility for this other guy!

 

[mikeyd]

Thanks for updating us. Hang on to your new electrician incase you find or suspect any other problems. In fact you realy should get him/her to check everything the previous cowboy did.

The problem was the first electrician had just put the wires into the earth and neutral in anyside.

I'm not an electrician, but I know enough about the subject to say that your 'first electrician' was also not an electrician.

 

[SimonH2]

... its split 50/50 RCD 32,32,32,32,32 RCD 16,16,16,10,10

If I follow that right, all your sockets are on one RCD, everything else is on the other. And I'm guessing that the lights are on the 10A breakers ?
Firstly, I would suggest that's not a good idea. If one breaker trips, you lose all the power (sockets) in the whole house - inconvenient but not in itself dangerous. If the other trips, then you lose all your lights - which means navigating your way to the panel to reset the RCD could be interesting at night

Secondly, 10A sounds a bit high for lighting circuits, and I'd suggest you check with your friendly second electrician that this is correct - though he should have noticed this when he was looking at the earlier problem.

Its now been sorted, The problem was the first electrician had just put the wires into the earth and neutral in anyside. So the RCD was tripping due to the change in input and output amps? Cant explain very well but I hope you understand.

Get the drift - he stuck the neutral and earth wires into random terminals, rather than matching them up. I agree with the others, he doesn't sound like a "proper" electrician - IMO his work is substandard (to be polite) and he should be reported.

 

[scousespark]

Why is there an issue using 10A breakers for the lights?

 

[SimonH2]

Why is there an issue using 10A breakers for the lights?

Are all light fittings and switches rated for 10A, or are some rated for only 6A ?

Is 1mm T&E rated for the current if covered with insulation as it would be above in a loft ? IIRC I think it is, but I don't have any tables with me (they're at home).

 

[Paul_C]

Is 1mm T&E rated for the current if covered with insulation as it would be above in a loft ? IIRC I think it is, but I don't have any tables with me (they're at home).

Yes, 11A, if not subject to other derating for grouping, temperature, etc.

http://www.tlc-direct.co.uk/Figures/Tab4.7.htm

 

[scousespark]

Using 1 mill with a 10A breaker should be okay, but I'd say it was a case of the 'spark' having them available rather than doing the calc to decide 10A was required.

Also, the circuits may be in 1.5

 

[Risteard]

Very common practice to use 10A devices for lighting. In fact the Wiring Regulations permit up to 16A devices to be used with standard luminaires.

As for the rating of the switches, surely the switches are not switching the entire load in any case but only a very small part of it, so again what is the issue?

 

[bernardgreen]

As for the rating of the switches, surely the switches are not switching the entire load in any case but only a very small part of it, so again what is the issue?

In the case of a fault on the circuit controlled by the switch leading to a high fault current then the 6 amp switch might be catastrophically destroyed before the 10 amp breaker operates.

 

[Risteard]

As for the rating of the switches, surely the switches are not switching the entire load in any case but only a very small part of it, so again what is the issue?

In the case of a fault on the circuit controlled by the switch leading to a high fault current then the 6 amp switch might be catastrophically destroyed before the 10 amp breaker operates.

What current would you expect to flow under short circuit or earth fault conditions?

 

[bernardgreen]

What current would you expect to flow under short circuit or earth fault conditions?

How short is a piece of errant copper ? It all depends on what the fault is and the impedances of he fault and the impedance of the supply from the network.

A dead short with a total lloop impedance of 0.5 ohms will allow a current of 460 amps to flow until protective devices operate or wires melt.

 

[Risteard]

What current would you expect to flow under short circuit or earth fault conditions?

How short is a piece of errant copper ? It all depends on what the fault is and the impedances of he fault and the impedance of the supply from the network.

A dead short with a total lloop impedance of 0.5 ohms will allow a current of 460 amps to flow until protective devices operate or wires melt.

And how will a 460A current for a very short duration cause a 6A switch irreparable damage yet leave a 10A one operating perfectly?

 

[bernardgreen]

And how will a 460A current for a very short duration cause a 6A switch irreparable damage yet leave a 10A one operating perfectly?

It wont.

That was a worse case example.

A system that allows 10 amps to be switched by a switch rated at 6 amps will have a high risk of the 6 amp switch's life time being short before arc eroded contacts start to become hot.