The main oven on my Smeg DUCO8CSS integrated oven trips the RCD after heating up (about 10~15 minutes). The small oven works fine without issue. All the articles I read on the internet pointed towards the fan element being faulty, so I bought a new one and fitted it and.... the problem still exists. I asked an electrician friend to have a look and they used an insulation tester that confirmed that the new fan element was fine, as was the fan motor and the light fitting. So I'm stuck in a quandary now as I don't know what the problem is, so I can't solve it. Does anyone have any ideas as to what it may be and if there are any associated checks I can do to prove it? Any help would be very appreciated.
Oven tripping RCD after heating up
- Thread starter Clarkkent
- Start date
Help Support Talk Electrician Forum:
- Joined
- Mar 28, 2008
- Messages
- 14,303
- Reaction score
- 948
Has the RCD been tested?
ie Is it oversensitive?
Is the oven on a dedicated or shared RCD?
If it is shared it may be a combination of multiple items exhibiting some natural leakage sufficient enough to trip the RCD.
(ovens are appliances that can have significant natural leakage)
In which case a dedicated RCBO for the oven circuit may help.
Guinness
ie Is it oversensitive?
Is the oven on a dedicated or shared RCD?
If it is shared it may be a combination of multiple items exhibiting some natural leakage sufficient enough to trip the RCD.
(ovens are appliances that can have significant natural leakage)
In which case a dedicated RCBO for the oven circuit may help.
Guinness
they often test fine when cold then fail when hot, so needs tested both cold & hot
Yes you need to get it hot, then test it.
My theory, (for what it's worth), is that the mineral insulation absorbs moisture from the atmosphere. This small amount of moisture disperses along the element length and has little effect on the insulation resistance measurement. When powered up, the residual moisture is driven by the rising heat towards the cool ends of the element, where it becomes more concentrated and consequently has a measurable lower resistance to the casing.
Hence, leakage current increases with increased temperature, until your rcd trips.
If you can keep it hot, on a non-rcd supply, for long enough you just might drive the moisture out of the element.
My theory, (for what it's worth), is that the mineral insulation absorbs moisture from the atmosphere. This small amount of moisture disperses along the element length and has little effect on the insulation resistance measurement. When powered up, the residual moisture is driven by the rising heat towards the cool ends of the element, where it becomes more concentrated and consequently has a measurable lower resistance to the casing.
Hence, leakage current increases with increased temperature, until your rcd trips.
If you can keep it hot, on a non-rcd supply, for long enough you just might drive the moisture out of the element.
sometimes needs this done on a new element, once dried out its fine. older elements though and they need replacment
