RCD - Cooker

[highspark]

Just fitted a cooker as soon as energised RCD triped. All wiring correct etc.

Tenant says had a few problems with intermittent tripping.

Old cooker was gas with ignition plugged into 13A socket fed from old electrical oven circuit 6mm cable. I have utilised this.

Did I/R Test on circuit. Live-neutral >500, Live-Earth >500. Neutral-Earth 1.45m ohms.

Ramped RCD at 33ma

1/2 timer IdeltaN - Trip 0'00ms

Faulty RCD yes.

But faulty circuit aswell? Under 2mohm

 

[Spazz]

do an insulation test on the cables and see what happens, you can always do a R1 + R2 as well or a Zs that will give you some ideas.

I take your at home now and not able to test it tonight

 

[highspark]

No testing tonight at home.

Here's the lowdown.

Extended 6mm Twin & earth cable between cooker point and cooker. Connected to cooker. Tripped upon energising restored and light came on on cooker. As soon as tenant turns cooker nob trips RCD.

Checked connections etc all ok.

Removed earths and cooker came on hob worked and oven (with earth removed). Restored earths done an IR test

L-E >500

L-N>500

N-E 1.45mohms bar to bar.

Ramped RCD at 33ma does this need replacing anyway?

Left property had a call fro
Customer saying RCD tripped and would not restore, this with oven circuit isolated via MCB. Cooker switch was in the on position so told customer to switch off! Once off RCD restored

 

[Deleted member 26818]

Simple solution: remove RCD.

 

[Spazz]

ok, that clears it up - do an IR between N-E tomorrow on the cooker side of the Isolator

Ot of interest you say you extended the T&E between the cooker point and cooker, did you test this connection using IR before engaging?

Also how did you extend it?

The extension you made could have failed and hence the tipping when the isolator is turned on.


Good Luck and keep us informed!

 

[Spazz]

And yes the RCD needs replacing at 33mA

Do the RCD Test on another circuit on the same RCD - if still getting 33mA check the timing and Replace the RCD.

 

[highspark]

I extended using a cooker extension unit.

And no did. It Ir extension before energising

 

[Edd]

edit. pointless post

 

[Spazz]

Work backwards then and start from the point your meant to once you have finished extending the circuit.

Go A, B, C, D, E, F, G, H, etc
NOT A, H

If you know what I mean - sometimes it works and some times it does not.

As you may know this is notifiable and therefore a Minor Works or EIC needs to be issued - where are you going to get the results if you have not tested it - please dont say you where going to make it up!!

I also take your a registered Electrician so we should not have to tell you that.

 

[highspark]

So you think we have an n-e on cooker unit?

 

[Spazz]

I think so, the IR Test says that

 

[Spazz]

Just a quick thought - when you IR Tested it did you do it on 250v DC or 500v DC.

If you did it on 250v DC you will have a higher reading than on 500v DC, then if did on 500v DC, you would of got below 1MOhm - making it a fail.

 

[highspark]

Simple solution: remove RCD.

nick think you are getting ahead of yourself there. All my work is signed off and tested correctly. However on this occasion I energised first. As I only extended cable to reach cooker as previous cooker was plugged direct into a 13a socket on this circuit. Yes a 6mm in a 13 a socket. I would not have expected my new cable of 2m length and to have a failed I/r

 

[Spazz]

Its was just a reminder more than anything - we have a go on at others on here who are DIYers who engage and hope it works, we should not be doing down this route ourselves!

It happens - we are in a rush to get home and we just try it before - not the best though as you found out.

Good luck tomorrow with sorting it - I think you have some ideas on where to go from here.

What ever happens dont remove the RCD as spinlondon said! the RCD is doing you a favor here even if you don't think so at this point

 

[AndyL]

L-E >500

L-N>500

N-E 1.45mohms bar to bar.

Did you carry out these tests with the cooker switch on or off.
If it was left on try re-testing with the cooker switch off, if that clears the low reading N-E then the fault lies on the load side, i.e the new cable or the cooker.
If it doesn't clear the fault disconnect the cpc and neutral from the ccu and re-test that way you'll know if it is your cooker circuit that's at fault