Oven wiring help please keeps tripping

Old leccy 007 · Oct 23, 2021

Hi all please could someone help, my ovens keep tripping the rcd see images for details basically from the cu I have 63 amp rcd with a 32 amp mcb type b from that run in 6mm t&e to an isolation switch 50 amp then more 6mm cable to a dual cooker outlet then 2x flex runs to 2x single ovens 2100w each oven power everything up all OK but then put both on full power just as I would when cooking and it trips the rcd going out of my mind as I just can't think why can anyone shed light onto this please

[ElectriciansForums.net] Oven wiring help please keeps tripping

Pretty Mouth · Oct 23, 2021

If the RCD is tripping then there is almost certainly a fault somewhere downstream of the RCD. It's unlikely you'll find it by trial and error, so I recommend you get an electrician competent in fault finding to look at it.

Mikegh · Oct 23, 2021

As above , you're going to need an electrician regardless

Probably downstream ,one of the ovens faulty

Or even the oven total loading tripping an N-E fault on the rcd ?

Mikegh · Oct 23, 2021

Have you tried using just one of the ovens ?

Might keep you cooking while you're waiting on the electrician ?

snowhead · Oct 23, 2021

Is this a new installation?
Or was it O.K before and has recently started tripping?

If new it can be a / both faulty oven elements, if old ovens it can be faulty elements.

As above have you tried each oven singly?

It may be that each oven, whether new or old has earth leakage on the oven element, not enough to trip the RCD, but the combined leagage is enough to trip.

Presumably you've checked all the connections for tightness?
Is there a cable trapped somewhere or nail or screw through one or both?

Electrics · Oct 23, 2021

Newb here so don't laugh if this is a stupid suggestion, but isn't it pointless having a 50a breaker after a 32a breaker? Or is the 50a just an isolator that is rated at 50a?

Mikegh · Oct 23, 2021

CamoElectric said:
Newb here so don't laugh if this is a stupid suggestion, but isn't it pointless having a 50a breaker after a 32a breaker? Or is the 50a just an isolator that is rated at 50a?

Isolator

Electrics · Oct 23, 2021

Mikegh said:
Isolator

Since it can only pull 32a max anyway because of the MCB, why not use a 32a isolator?

Pretty Mouth · Oct 23, 2021

CamoElectric said:
Since it can only pull 32a max anyway because of the MCB, why not use a 32a isolator?

Cooker switches (isolators) usually come as 45 or 50A as standard

Mikegh · Oct 23, 2021

As above I suppose domestic isolators just standardized to exceed standard loads

So 20/40/50 etc

loz2754 · Oct 23, 2021

I would begin by testing the circuit, with the ovens disconnected, and the L and N disconnected from the consumer unit.
As a retired electrician, do you still have an insulation resistance test instrument?

If the circuit wiring checks out ok, then I might subject the ovens to an appliance tester. And/or use my earth leakage clamp meter on the L and N of the RCD.
In other words, a logical step by step approach usually works best.

Mikegh · Oct 23, 2021

Hmm , or would you begin by switching on each oven separately

Electrics · Oct 23, 2021

Pretty Mouth said:
Cooker switches (isolators) usually come as 45 or 50A as standard

Gotcha thanks for the info.

loz2754 · Oct 23, 2021

Mikegh said:
Hmm , or would you begin by switching on each oven separately

Hmmmmm, yes I probably would?

Avo Mk8 · Oct 23, 2021

If they are brand new ovens, not been used before, the elements may have absorbed moisture in storage, and the combined leakage can trip the rcd. Once they dry out they'll be fine.
(this is a known effect - I'm not making this up!)
If one oven will stay on, you could try running one and then the other for a while, and check the effect goes away.

The more satisfactory course of action is to measure the earth leakage current.