Loud pop, bright flash, tripped circuit, dead ovens

[NathanM]

Hello,
The blinding flash under my ceramic top happened with 2 halogen hobs lit just as I turned on the top oven. It destroyed the MCB in consumer unit. It turns out that the MCB being only 16A wasn’t big enough for a 10KW Electrolux ECK6046W cooker anyway, and I’ve replaced it with a 20A breaker having done the sparky’s diversity calc. But the problem with the cooker remains this: Neither oven works, but the 4 hobs and grill do work. The bottom oven is completely dead, no fan/light/heat, and the top oven causes the flash when the heat is turned on, yet the light and fan work.

I took the back panel off the cooker having read info on this site and there is a big burn mark on the inside of the rear panel and black charring on lots of cables, though none of the cables are actually damaged.
I’ve inspeced the element in the bottom oven and it appears to be fine and with a multimeter across it’s terminals it has a resistance of about 250 Ohms.

I slid out the element for the top oven (not fan assisted) and it looks fine too and also has a resistance, slightly lower than the large bottom oven element.

The elements for the grill are fine too, as expected because it works still.

So can anyone take a pot-shot at what might be going on with my cooker? I’m guessing the bright electrical flash is the result of a short somewhere, backed-up by the burn marks round the back on the inside, but I can’t see anything that’s gone wrong so don’t know now what to do troubleshoot. The cooker is only 4 years old. Thanks. Nathan.

[kwatt]

Re: Loud pop, bright flash, tripped circuit, dead ovens

Sounds like a dead short somewhere.

Switches? Safety stats?

It could be anything TBH.

K.

[NathanM]

Re: Loud pop, bright flash, tripped circuit, dead ovens

A bit more investigation and re-checking resistances.

Cable to the cooker is 6mm2 and is about 15m from the consumer unit.
I re-checked the resistance of the elements on an easier to read scale:
Grill 1: 30ohm
Grill 2: 120ohm
Top oven: 50ohm
Bottom oven: 25ohm

I’ve since removed all the connectors for the elements and taped them up with insulating tape to see where a fault might be by isolating one element at a time.
The bottom oven, whether it’s on its own or not, will not work: no light, no fan, no heat.
The top oven (not fan assissted) works fine on it’s own.
The grill elements both work fine.
The hobs all work fine.

When connecting the grill and top oven together now (they share a blue wire) I get no problem where as before there was the bright flash/pop and the circuit tripped. But I still can’t use the top oven because in my ferreting around at the back in order to check the top oven element I had to remove part of the insulation material which just disintegrated between my fingers. Can you suggest where I can buy this stuff afresh as my internet searches have turned up nothing.

Looking for a local repair shop now to see if they have ideas and possibly a call-out service to try and get this sorted if I can’t do it myself. I’ll be properly annoyed if I can’t get to the bottom of it though. But there is a lot of wiring going on round the back and under the cook top. I wish electrolux did a wiring diagram. If I can fix motorbike electrics I don’t see why I shouldn’t be able to fathom this and get the appropriate parts ordered. Chalk and cheese?

Read more: http://www.diynot.com/forums/viewtopic. … 85#1960285#ixzz1JbuaMmbL

[kwatt]

Re: Loud pop, bright flash, tripped circuit, dead ovens

Hold the phone… live testing! Relying on bits of insulating tape? Are you insane?

What happens if it were a dead short from live to Earth, you’d possibly be zapped a good ‘un and dead or at best given a bl00dy big fright and a good jolt if you so much as touched the wrong bit of casing.

Live testing like this is stupid, completely irresponsible and not in any way condoned on this site. You can test every single component in an oven and pretty much any other appliance without power applied.

240VAC kills, it’s that simple.

All your elements have a circuit, that’s all you need to know unless you have a megger that you can test the earth with. Testing them live to see that they heat up accomplishes absolutely nothing and, proves nothing. If it was a short to Earth there then the RCD would pop as soon as you selected the element that was being energised.

Which leaves you with three possibilities pretty much as it’s a basic static oven, the oven selector switch, some form of thermal fuse or safety thermostat being faulty or the wiring itself compromised in some manner.

The insulation we just used fibre glass insulation.

HTH and try not to play with live electricity please.

K.

[NathanM]

Re: Loud pop, bright flash, tripped circuit, dead ovens

Afternoon kwatt,
I’ve not had the power on while I’ve been round the back.
It’s been off on the wall unless I’ve been infront of the cooker, with the top correctly in place only with the various elements isolated at the back, and taped so the metal spade connectors coudln’t touch anything while they weren’t in their female connector on the elements. I know you only get once chance with electrics, so I’ve not been gambling in any way while the power has been on, but have been trying to replicate the problem, which I now can’t, though the bottom over remains dead in all respects (light, fan, heat.) In the mean time between getting it properly sorted, I have some spare loft roll that I’ll insulate the back with so we can use the top oven without losing all the heat out the back.
Thanks for the concern and for the help. Nathan.

[NathanM]

Re: Loud pop, bright flash, tripped circuit, dead ovens

I couldn’t work out how to get images in posts on here, but this link should take you to the image I put on DIYNOT
http://www.diynot.com/network/NathanM1/albums/8547/33163

[Author]

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