Ideas on rcd fault

[ses]

I have a customer who's rcd trips when the cooker is left on for over an hour i.e when making casserole

Info:

Mk 80amp 30ma rcd
Kitchen sockets 32amp type b

Feeding washing machine, dishwasher, kettle, microwave, toaster, cooker, fridge, ignition hob

Badly designed circuit so i would have thought overload but its the rcd that trips not the mcb

Rcd tests fine
Trips at 18ma and 20ma

Zs fine
Insulation resistance fine

Cooker is 2160 watts so only a small load on its own.

Checked all connections they are tight.

Maybe high resistance joint i thought heating up during time oven is on?

Ideas please

 

[telectrix]

or an element breaking down when hot.

 

[ses]

Good idea the oven is a few months old so i should check if its only been happening since it was installed

Thanks telex

 

[tombennetts]

knackered cooker? My parents brought a replacement element from ebay to get them buy until the kitchen refurb was done. that would trip the RCD after a while. My wife actually got a shock from the oven eventually whilst getting a metal pan out of it - needless to say their electrics had an overhaul after that!

 

[ses]

Its times like this i value this forum, great to get help as so easy to miss the obvious

 

[Jay Sparks]

Its times like this i value this forum, great to get help as so easy to miss the obvious

Sometimes the obvious is miles away, when youv'e been at it all day....a fresh mind is always a good thing....IF it comes without the bull crap!!!!lol

 

[HandySparks]

If you've got a clamp meter, put it round both tails. Preferably one designed for earth leakage, but something with a resolution of 1mA is probably good enough in this case.

If the differential current climbs as the elements heat up and then the RCD trips at the expected value, you've demonstrated exactly where the fault lies.

 

[graham123]

Do an earth leakage test on the cooker,

 

[GLENNSPARK]

Sometimes the obvious is miles away, when youv'e been at it all day....a fresh mind is always a good thing....IF it comes without the bull crap!!!!lol

guess that counts me out then...

 

[Jay Sparks]

guess that counts me out then...

Probably counts most of em out on here glen...lol