Cooker problem

[All Jobs]

Hi all, have just done EICR on a property, managed to get the house to pass with some corrections along the way. House is an old thatched place, wiring about 40 yeas old, RCD main switch in the consumer unit.

Before I started, customer advised me they had an issue with their oven, when they turn their oven on sometimes it tripped the RCD. If they tuned some of the MCB's off, it would stay on. It is an AEG induction hob/oven

I carried out electrical checks on the cooker radial circuit twice, just to make sure, readings came out ok. As soon as connect to the oven, trips RCD main switch. House is on a TT system, I know you get some leakage back from an oven but I cannot get my head round this problem. With cooker disconnected from outlet and cooker cable hanging loose, no problem, cooker radial circuit is ok, powers up fine, no trip the RCD.

To use oven, turn some lighting circuits off, seems to run OK?

Cabling in property is about 40 years old, have suggested to customer partial rewire.

Any advice would be appreciated. New to electrics, don't know a lot yet, any help greatly appreciated. Thank you.

 

[Plonker 3]

New to electrics, don't know a lot yet, any help greatly appreciated. Thank you.

This is a very worrying statement from someone carrying out a EICR.

 

[telectrix]

an earth leakage clamp meter is what's needed here. you've probably got some leakage overall and the cooker takes it over the threshold. a lot of RCDs trip at 23-25mA, so a ramp test could be done, first with all MCBs off, then repeat with the MCBs switched on 1 BY 1.

 

[Octopus]

I would suggest its the issue of "accumlated" earth leakage when you have some coming off a number of appliances and when the cooker is turned on you get the RCD to trip.

Difficult to prove without a specific meter.

I was doing tests on this very issue this morning. Done and dusted in about 30 minutes, with a list of circuits and the associated earth leakage per circuit.

Metrel MD9270 is what I used - expensive but invaluable.

 

[telectrix]

i posted a similar post concerning acc. leakage and suggested ramp testing with breakers turned on 1 at a time, but the forum lost it in danspace.

 

[Geordie Spark]

i posted a similar post concerning acc. leakage and suggested ramp testing with breakers turned on 1 at a time, but the forum lost it in danspace.

I read your comment before it disappeared.

I will be your witness to its existence!!!

 

[All Jobs]

Thanks for replies above guys. Just had a thought to overcome problem. Possibly as suggested by you all above, accumulated earth leakage across the property.

I am thinking split the tails, separate consumer unit, put the cooker on this. Any thoughts please?

 

[Octopus]

Thanks for replies above guys. Just had a thought to overcome problem. Possibly as suggested by you all above, accumulated earth leakage across the property.

I am thinking split the tails, separate consumer unit, put the cooker on this. Any thoughts please?

Hum, what were the IR results like on the individual circuits?

Maybe replace the whole CU with a RCBO unit?

 

[davesparks]

Or maybe work out which element is to blame and replace that element?

By putting it on to a seperate RCD you are fixing anything, just bosging over the problem until the element gets a bit older and trips the RCD you put it on.

I'm curious as to how on earth the property managed to pass an EICR, considering the only possible outcomes are satisfactory or unsatisfactory?

And if it requires a partial rewire as you suggested above then how could it possibly have passed anything??

 

[All Jobs]

Thanks for above guys. Davesparks, EICR report came out satisfactory as cooker circuit passed with cooker disconnected. Cooker is still disconnected. All other circuits ok. I don't have the Earth Leakage Detector Metrel MD9270 so cant detect earth leakage as mentioned above. I put a note recommending partial rewire of light circuits as exposed light cables beginning to show signs of age, PVC getting hard. Further comments help/advice welcome.

 

[davesparks]

PVC getting hard? That sounds very unusual, Can't say I've ever seen that happen to PVC cable!

I'd be looking at what other influences could have caused this.

How did you test the hardness of the PVC?

 

[telectrix]

pvc does get hard and brittle esp. if heat from lights is to blame. this is the reason that heat sleeving is supplied with some fittings.

 

[All Jobs]

I actually listed it as PVC showing signs of deterioration. (PVC painted over, stretched around ceiling beams/timbers in the house etc). I use the wrong word "hard" above davesparks!!

Just trying to establish best way forward to sort this problem for the customer. Any further advice appreciated.

 

[telectrix]

get 'em to buy a gas cooker. also has added benefit of being able to commit suicide when they get your invoice.

 

[Geordie Spark]

get 'em to buy a gas cooker. also has added benefit of being able to commit suicide when they get your invoice.

Cheaper to run too - if you apply a bit of ingenuity.

 

[UKMeterman]

Ok.
Suspect the new cooker is an induction cooker and so has a lot of emc filters that will have a LOT of earth leakage. Ramp test exisiting RCD to check that it is still in spec, check earth leakage of cooker and check measured value with manfucaturer. Suggest upgrading install to high integrity board and put the cooker on seperate RCBO.

 

[All Jobs]

Referring to Dilb's post, (I don't use forums a lot so not used to using them).



When I say don't know a lot, I mean I don't know as much as a lot of people on this site. There are guys out there been doing this a lot longer than me, have more experience and knowledge and may be able to pass on some advice. I only got qualified 18 months ago, I thought that was the idea of this forum, to help us new guys if needed?

 

[Geordie Spark]

When I say don't know a lot, I mean I don't know as much as a lot of people on this site. There are guys out there been doing this a lot longer than me, have more experience and knowledge and may be able to pass on some advice. I only got qualified 18 months ago, I thought that was the idea of this forum, to help us new guys if needed?

Are you now saying you have had no help??

Were posts: #3,4, 5, 8, 9,11 &16 not helpful?

What more do you want???!!!

We can only offer advice based on what information YOU bring to the table - Sparking we do rather well but we are complete shyte at clairvoyancy!!

Go away and have a word with yourself!!!

 

[All Jobs]

When I say don't know a lot, I mean I don't know as much as a lot of people on this forum site. Only qualified 18 months ago, have not got the experience like a lot of you guys, still learning. I thought this site was to perhaps help younger inexperienced members, give advice if you can

 

[Plonker 3]

So what qualifications do you posses and how long did you spend at college?