Problems after new consumer unit fitted

[leigh jones]

I have had a new consumer unit fitted to replace my old baker light fuse wire one.
Since it has been fitted the double oven and separate hob are tripping the RCD (both are wired through the same isolator)
I have disconnected the oven and tried to use the hob and vice versa and both still trip the RCD, I then thought that it could be the switch that is faulty so replaced that but still it trips.
I'm running out of ideas now so can anyone help

 

[deadshort]

Perhaps you need you electrician to return with test kit to determine the cause of the fault. If it trips as soon as the appliance is switched on it could be a wiring fault on the circuit not the appliance. Usually a neutral on the wrong terminal in the consumer unit.

DS

 

[bernardgreen]

It could also be a Neutral to Earth fault on any ciruit supplied by the RCD. Even if that faulty circuit is turned OFF by switching OFF the MCB supplying it the Neutral is still connected. The fault appears to be on the circuit feeding the oven and / or hobs as the RCD trips when they are turned on. What happens is that some of the current on the Neutral from the oven can sneak through the fault on the other circuit to the ground and thus by pass the RCD sense coil.

Neutral_Earth_trip

• bernardgreen
• 16 Jan 2011
• 48

The electrician will need to disconnect Live and Neutral on each circuit when testing for earth leakage faults.

 

[leigh jones]

Could I also prove it by wiring in a temp supply from the CU to the hob and see if it trips

 

[bernardgreen]

Could I also prove it by wiring in a temp supply from the CU to the hob and see if it trips

It would have to be from a circuit NOT protected by that RCD

 

[ban-all-sheds]

baker light

https://en.wikipedia.org/wiki/Bakelite

 

[ban-all-sheds]

Could I also prove it by wiring in a temp supply from the CU to the hob and see if it trips

Not an easy thing to do.

 

[Chri5]

If its a twin rcd cu, temporary move the circuit cabling from RCD 1 to RCD 2, if it trips you know its the cable or appliances.

If it doesn't then the fault is something on one or a mix of circuits on that side.

RCD's trip when greater than 30mA. Could be a combo of appliances leaking.

If you have (say) 4 circuits on the RCD that is tripping have you tried turning off all the mcbs expect the cooker one, and then tried the cooker? Does it still trip whenall other mcbs on the rcd are off?


Best bet would be to get the person who changed the board back.

 

[ban-all-sheds]

If you have (say) 4 circuits on the RCD that is tripping have you tried turning off all the mcbs expect the cooker one, and then tried the cooker?

Won't be definitive unless the MCBs are double pole.

Which they won't be.

 

[securespark]

Best bet would be to get the person who changed the board back.

Ho, ho!

If he pulled a stunt like getting the neutral bars mixed up, he doesn't sound like the sort of guy who would come back.

Nor has the installation been tested as per 7671. If it had been, this would have been picked up & corrected.

 

[JohnW2]

Since it has been fitted the double oven and separate hob are tripping the RCD (both are wired through the same isolator). I have disconnected the oven and tried to use the hob and vice versa and both still trip the RCD,...

Do I take it that your cooker switch ("cooker control unit") done not have a socket built into it? If it did, you could try plugging something into it (kettle, toaster etc.) and see if that caused the RCD to trip.

Kind Regards, John

 

[JohnW2]

If he pulled a stunt like getting the neutral bars mixed up, he doesn't sound like the sort of guy who would come back.

True. However, if (as seems probable, if it's new) the CU has dual RCDs, one would probably expect both of them to trip if the neutrals were 'mixed up' in the CU, would't one? - and we haven't been told that this is what is happening.

Kind Regards, John

 

[leigh jones]

Yes it has to RCD's and both of them trip when load is put onto the cooker/hob circuit

 

[leigh jones]

Hi John, yes it has a separate socket on it, and when something is plugged into it, it trips

 

[Spark123]

Sounds like a neutral in the wrong bar in the consumer unit, get the electrician back to correct it. Should only take them 5 mins.