TT system tripping

[mannex]

I am working on a TT system and the electrics are tripping all the time, I have narrowed it down to the downstairs light circuit. Everytime when this light circuit is connected at the board and if I try to turn the oven (on the cooker circuit) or boil a kettle. ( ring main) it trips the electrics, but when the lightning circuit is disconnected everything works fine. I have done the insulation. Test and its ok am now running out of idea. Because it seems the lighting circuit is interfering with the cooker circuit and ring downstairs main. But how its happening........... I am hitting a brick wall.

Help please

I had to reposition a light switch on this light circuit and I have since double checked my wiring. The rcd is tripping not the mcb

 

[trev]

So you've done an IR on the lighting but nothing else? Have you tried IR between the circuits? What is tripping? MCB or RCD?
Etc
Etc

 

[Sintra]

What exactly is tripping?

 

[Octopus]

You have a fault on the lighting circuit. Time for a bit of fault finding

 

[frontier219]

Without being there, sounds like it could be an N-E fault on the lighting circuit to me!

 

[frontier219]

You have a fault on the lighting circuit. Time for a bit of fault finding

Beat me to it!

 

[yellowvanman]

The reason the RCD is tripping is you've probably got a N-E fault on the lighting circuit.

When you have a high current appliance on (oven/kettle) then the resistance of the fault is small enough to divert a small amount of current through the N-E fault!

 

[GMES]

Mannex your profile says your still in training, have you got a mentor or are you doing this job alone, also you say you're working on the lights is this to fix the fault or has the fault occurred whilst working on the circuit.
Can you give us as much info as possible.

 

[123]

You have a fault on the lighting circuit. Time for a bit of fault finding

Totally

Most likely place is any external fittings/switches sitting full of water!

 

[mannex]

its the rcd which is tripping 100MA

 

[davesparks]

its the rcd which is tripping 100MA

That's one hell of a big fault current if it's tripping a 100MA RCD!

Are you sure it's not a 100mA RCD?

 

[trev]

What were your IR results on the lighting? I agree with the rest of the lads, it's N-E

 

[Octopus]

You need to remove ALL the lamps and do a proper ire test with all switches on and if you have 2 way switching, tests with the switches in each position.

 

[davesparks]

Totally

Most likely place is any external fittings/switches sitting full of water!

In this case a water logged external light is unlikely as that would normally be present on all conductors wheras this has the classic symptoms of a N-E fault.

 

[Sintra]

What tests have been done on the RCD?