Electric oven fault.

[Agile]

I am asking on behalf of a landlord whose tenant has reported a problem.

They have an electric oven which apparently trips the MCB regularly. Perhaps every 10 to 15 minutes.

That would imply to me that the oven element is taking too much current and tripping the MCB.

My question is "is it a common fault for electric oven elements to fail such that they may take 50% to 100% higher current ? "

 

[Rodders53]

What moron keeps resetting a safety device every 10 to 15 minutes?

Assuming it has all worked properly for many years then more likely it's a faulty MCB and tripping well under its rated current.

Unless it is the RCD and not the MCB that trips, when it may a Live or Neutral to Earth fault that manifests when something gets to a certain temperature?

Electrician or Appliance Repair person? That is the question.

LL needs to confirm exactly what trips.

 

[Agile]

This is the tenant reporting everything. The oven is only four years old so relatively new.

But the landlord does think that it is the MCB tripping.

But do MCBs often start tripping at lower currents?

I have never encountered that or even read about it on here.

 

[RandomGrinch]

In my (fairly limited) experience of PATing plug-in ovens, when they fail, they have almost always failed insulation resistance tests. When the elements are damaged, the mineral insulation within the element is hygroscopic.
Without having a pre-warning from a PAT, the oven will eventually trip the RCD.
And conversely to your situation, the IR improves when the oven warms up.

"is it a common fault for electric oven elements to fail such that they may take 50% to 100% higher current ? "

IMO, I don't think it is common for an oven to trip an MCB, given the circumstances you describe!

 

[Murdochcat]

This is the tenant reporting everything. The oven is only four years old so relatively new.

But the landlord does think that it is the MCB tripping.

But do MCBs often start tripping at lower currents?

I have never encountered that or even read about it on here.

I think we need to remove the "think" from what the LL is saying and get the facts.

Is it a RCBO rather than a MCB?

A photo of the CU would help immensely

 

[opps]

My mum's built in combi-microwave started tripping the RCD.

Admittedly it was more than 4 years old.

She paid for a Siemens engineer to inspect it. He pointed to the rust holes in the top of the oven. It turns out that the installation manual states that an air vent must be fitted in the plinth. The original kitchen fitter didn't RTFM.

I had to fit the replacement (newer model) if cost £1300, but I did fit a vent into the plinth...

 

[Rodders53]

I have never encountered that or even read about it on here.

Strange. This is where I've read about it, I believe; but perhaps not? Not common but then nor are faulty RCDs.

Get the tenant to supply picture of tripping device to be certain what is happening.

Equally it could be a loose connection on the Oven MCB causing overheating of it and thereby an early trip (and a potential fire if left and repeatedly reset). Or adjacent MCBs heating the oven MCB as well... e.g. a water heater.

Send in a sparky in to check and if they determine it's an appliance fault send in a different person to fix the oven.

 

[Harry Bloomfield]

But do MCBs often start tripping at lower currents?

I have never encountered that or even read about it on here.

I would expect a MCB trip on a L to E developing fault, or a RCD to trip on L to E, or N to E leakage. Normally I would expect an element to draw less current as they age, and the diameter of the filament/element is eroded.

 

[Deleted member 267285]

Could a loose connection cause it, eg a loose neutral?

 

[oldbutnotdead]

Another favourite fail point for ovens. Under the covers there is usually a load of rockwool type insulation, within which there are also uninsulated connections (totally fine, the covers require a screwdriver to remove). If that rockwool becomes laden with grease and dust it can form a conductive path to ground sufficient to trip a 30 mA RCD.

Best route forward (imho) would be an electrician but warn them it may be a portable appliance issue so bring suitable test gear.