Electric hob tripping RCD

[Simon_]

Went to visit a customer tonight briefly to have a look at a electric hob that was fitted last year when the new kitchen was fitted. All has worked fine until last week when they switched on the cooker switch/socket for the hob which tripped the RCD. They had the hob checked under warranty as 2 plates didn't work so it was replaced. Tripped electrics again. British Gas electrical came and checked the wiring and did an earth loop impedence test all ok but no IR test!? Said that the problem may be the switch/socket which is about 15 years old or the cable to CU. Any suggestions before I check the IR? Could it be earth leakage? Wondering why it's taken so long for it to trip it.

 

[telectrix]

ramp test the RCD as well. could be that the old hob caused a lot of tripping. RCD might be goosed.

 

[Flyingsparks]

Sounds like earth leakage problem on one of the elements or it could be that some liquid has managed to get inside one of the control switches.
Insulation resistance test is needed to trace this fault.

 

[SirKit Breaker]

Crap oven, break down of insulation, enough to cause RCD trip. Try and borrow a PAT tester that does earth leakage, and PAT the oven. Check the fixed installation, if no faults, then tell em to buy a new oven.

Cheers............Howard

 

[Simon_]

Thanks I'll do that. They haven't mentioned any previous tripping probs. I'm hoping it isn't wiring as its a ground floor flat and the cu is in the hallway cupboard. Not an easy rewire!

 

[Goody]

I had a similar issue where a particular element (the rest three were OK) kept tripping the RCD but the circuit tested OK. I simply advised them either to replace the oven or not use that element; they now use the oven minus an element.

 

[Simon_]

I had a similar issue where a particular element (the rest three were OK) kept tripping the RCD but the circuit tested OK. I simply advised them either to replace the oven or not use that element; they now use the oven minus an element.

They had the elements tested and had a new electric hob fitted but the engineer said the elements were fine. It's separate to the oven too.

 

[Dcf]

for these items i find earth leakage clamp right handy.failing that as a previous post use a pat tester with sub leakage test.put it this way i had a large range cooker recently that when it was on full chat was leaking 13-15mA to earth found the fault with my clamp meter pretty quickly.

 

[needasparks]

Can't add much to others really only thing i will say is you mentioned when they switched it on by the isolator,
Could this be the culprit ?
I know sometimes when testing if one pole connects before another on some inductive/resistive loads it can create a slight surge on one line and i have had an rcd trip on a couple of occations through this.

 

[ackbarthestar]

I've got a cheapo cooker to fix next week. Had a look at it last week and told the customer that it was cheap. She agreed..
By the time we've finished it will have gone up in price !
:drunk:

 

[marcus2610]

What type of hob is it?? hotplate, halogen, induction?? if its hotplate and its got wet, water could have gotten inside, stick it on a circuit thats not rcd protected and dry it out for half an hr then retest with rcd protection if it doesnt trip sorted. Fault persists, disconnect each hob and ir/pat test, all fine then move on to the switches again testing each one in turn, these are prone to blowing and cause rcd trip, even brand new ones. Hope this helps.

 

[needasparks]

What type of hob is it?? hotplate, halogen, induction?? if its hotplate and its got wet, water could have gotten inside, stick it on a circuit thats not rcd protected and dry it out for half an hr then retest with rcd protection if it doesnt trip sorted. Fault persists, disconnect each hob and ir/pat test, all fine then move on to the switches again testing each one in turn, these are prone to blowing and cause rcd trip, even brand new ones. Hope this helps.

Good idea and i see where your going but may be worth IR testing first in case its a dead short to earth and can cause more damage if that is the problem.

 

[1shortcircuit]

Although I am fairly new to the game one thing I have learnt is this...

Never believe what you are told, let YOUR OWN tests provide you with the answers:thumbsup

The information you are being given is worthless without conducting your own Insulation Resistance test on the circuit first - All the way to the end of the cable that connects to the oven so be prepared to remove it