cooker and rcd!

[Hawk]

Had a look at a job where the cooker, protected by 100mA rcd, trips intermittently. Sometimes it can go for weeks without any problem.
The cooker is only 2 years old. I have carried out an insulation resistance test on all the cables which was >999 and also a ramp test of the rcd which trips at 85mA. Pulled the cooker out and checked all the connections which are fine. What I did discover was a brown coloured like grease behind the cooker on the wall and on the cooker connection plate which I would assume is from moisture.
Anyone any ideas as all I can think of is moisture which is causing it to trip.

 

[Leesparkykent]

Is it tripping the rcd when in use or when being switched on or off?

 

[Hawk]

When in use. Customer said she had the oven on with the dinner in and after about 20mins it tripped and wouldn't reset until after a few attempts

 

[kenny7askew]

most likely element fault when heating up,if slime was conductive it would trip even when not in use

 

[Hawk]

The cooker is only 2 years old though.

 

[freetimebet12]

new elements are rubish

 

[Simonslimline]

The cooker is only 2 years old though.

Doesn't mean it cant fail.

 

[Revolver Ocelot]

maybe can be a faulty plate ...
look well if them have any mini crack and the rcd tripping only when the costumer put a wet pot on it.


It is just an idea

 

[Marvo]

new elements are rubish

:rofl::rofl:

 

[Midwest]

Had a look at a job where the cooker, protected by 100mA rcd, trips intermittently. Sometimes it can go for weeks without any problem.
The cooker is only 2 years old. I have carried out an insulation resistance test on all the cables which was >999 and also a ramp test of the rcd which trips at 85mA. Pulled the cooker out and checked all the connections which are fine. What I did discover was a brown coloured like grease behind the cooker on the wall and on the cooker connection plate which I would assume is from moisture.
Anyone any ideas as all I can think of is moisture which is causing it to trip.

If you have a clamp meter, you could try clamping it, to see what earth leakage you get, trying each plate/element in turn and then altogether. Brown coloured grease, could be the remains of the last chip dinner. Insulation resistance decreases as temperature rises.

 

[Marvo]

^^ As per Midwest, clamp the supply L+N together in an E/L clamp meter, run each element in turn for a few minutes or until red hot and watch for any that change significantly in IR value.

 

[Deleted member 26818]

Black iron heating elements absorbe moisture from the atmosphere, which can cause earth leakage until the moisture is dissipated by the heat.
New cookers and those unused for any length of time are prone to this.
However, that doesn't preclude there being a fault in an element.
Often faults can be identified simply by looking for bright spots on the element when it is in use.

 

[NDG Elecs]

I've had ovens trip the RCD in the past when customer has cooked there bacon literally 15mm from the element. Said they liked it crispy! I surmised that the high water content in supermarket bacon was forced out as steam too quickly and got into a damaged part of the element. Had similiar with customer deciding to steam clean a microwave by putting a bowl of water on high for 10 mins..

Simple job to clamp it and go through each element one at a time to see if anything shows up.

 

[Geordie Spark]

Doesn't mean it cant fail.

I once put a brand new lamp in my outside bog. It lasted less than a week.

I just switched it on & it went "POP"!!! :hump:

 

[Deleted member 9648]

IR test the entire installation as well, it may be the case that a N-E fault somewhere else on the installation is to blame and only causes tripping when a large load is running. Most likely cause is elements though ,which can be clear when cold but low when hot.
I had a similar issue Tuesday, cooker around 5 megs cold,but after heating for 20 mins or so oven element dropped to 0.02 megs.