Rangemaster Cooker tripping RCD

[autocolor]

Have a Rangemaster fully electric cooker installed in 2004, all have been well running off an old fuse wire CU, but have just had a new MK 10 way CU installed so now I have an issue with the RCD tripping which I have traced to the cooker.
The system worked well for several days, then out went the RCD, switched back on and all was well for another few days then out again, this time I could not engage the RCD with the cooker switched on so turned off at the main cooker switch and everything is fine. Left overnight and the cooker could then be switched on OK , went through the various cooker components one at a time and all worked OK without tripping, used two hobs to cook a meal then about two hours later out goes the RCD with the cooker only running the LCD clock. Thoughts as to what is going on here please!!
I have seen a few ideas on here reference running the cooker either from the non RCD side of the CU which seems a bit odd, or installing a higher value 100ma RCD for the cooker only, which seems to defeat the object of having an RCD in the first place?
FYI cooker is a Rangemaster Classic 90 Ceramic 230v and was new in 2004 total rating with everything operational 14.8KW. House was rewired back in about 1980 so running mostly on 30a cable from that time with newer from switch to cooker

 

[Thefailsafe2012]

Who installed the new board? Any tests been done? Could be an element(s) on its way out

 

[snowhead]

I'd say definitely an element on it's way out.

 

[Octopus]

Have a Rangemaster fully electric cooker installed in 2004, all have been well running off an old fuse wire CU, but have just had a new MK 10 way CU installed so now I have an issue with the RCD tripping which I have traced to the cooker.
The system worked well for several days, then out went the RCD, switched back on and all was well for another few days then out again, this time I could not engage the RCD with the cooker switched on so turned off at the main cooker switch and everything is fine. Left overnight and the cooker could then be switched on OK , went through the various cooker components one at a time and all worked OK without tripping, used two hobs to cook a meal then about two hours later out goes the RCD with the cooker only running the LCD clock. Thoughts as to what is going on here please!!
I have seen a few ideas on here reference running the cooker either from the non RCD side of the CU which seems a bit odd, or installing a higher value 100ma RCD for the cooker only, which seems to defeat the object of having an RCD in the first place?
FYI cooker is a Rangemaster Classic 90 Ceramic 230v and was new in 2004 total rating with everything operational 14.8KW. House was rewired back in about 1980 so running mostly on 30a cable from that time with newer from switch to cooker

What were the IR results for the cooker circuit?

 

[tony mc]

Get the spark who installed the CU back to do a few tests and when he or she is there check to see if your CU is subject to the recall if it is a MK Sentry CU !

 

[Geordie Spark]

My mate has just bought one of these all electric big range cooker things with a halogen hob. I have only glanced at it and scanned through the manufacturer's instructions and can't remember what make / brand it is, but I will be fitting it within the next week or so. I WILL pay it more attention then, but while scan reading the instructions I saw a line or two stating that there was / is a possibility that it will trip an RCD.

It then went on to describe ways around this, but - as I say - I didn't read it thoroughly at the time, but will do later & post on here what I find.

Hope that helps.

 

[SJD]

From a Rangemaster user guide:

Current Operated Earth Leakage Breakers
The combined use of your cooker and other domestic appliances may cause nuisance tripping, so we recommend that the cooker is protected on an individual RCD (Residual Current Device) or RCBO (Residual Current Breaker with Overload).

 

[tony mc]

It will be interesting to see what the manufacturer says the leakage is as it should be no more that 3.5mA for any fixed equipment

 

[autocolor]

Thanks for the ideas, this is tripping out whilst nothing is on just the clock would a faulty element cause that? As for testing the electrician spent two hours tresting and results were within specs but I don't have details to hand. Yes rangemaster do quote that it may cause tripping if used with other compliances but this is tripping out just standing idle, last night it went out whilst the oil boiler was running but not when it switched on it had been running for 20_30 mins. What's this about a recall? Any more ideas?

 

[tony mc]

If that's the case I doubt its the cooker that's tripping the RCD. What other circuits are on that RCD because you could be looking at the wrong thing.The electrician should know this and to test the cooker and elements is a straight forward test especially with a earth leakage clamp meter when all the IR tests are showing clear! Google MK Sentry RECALL re your CU if it is a Sentry unit and if you have any doubts contact your electrician for advice.

 

[stan794]

Check connections at the back of cooker, I had this last week turned out connection was iffy, burnt out neutral.

 

[Octopus]

Thanks for the ideas, this is tripping out whilst nothing is on just the clock would a faulty element cause that? As for testing the electrician spent two hours tresting and results were within specs but I don't have details to hand. Yes rangemaster do quote that it may cause tripping if used with other compliances but this is tripping out just standing idle, last night it went out whilst the oil boiler was running but not when it switched on it had been running for 20_30 mins. What's this about a recall? Any more ideas?

When the sparky changed your cu he would have given you an EIC and one sheet of the EIC is a schedule of test results - could you look these up?

 

[autocolor]

Definitely looking at the right thing here, as when the RCD trips it cannot be reset unless I switch off the cooker at the wall, I then have to wait for several hours before the cooker itself can be turned on again without tripping.
The electrician did complete the EIC but only manually so will forward the results to me once transferred to his laptop, he has the paper copies.
In the mean time I will pull the cooker out to take a quick look at the connections, don't worry I wont be doing any remedial work myself as I am only a DIYer and no formal qualifications, but I like to understand what is going on.

 

[Rampantchilli]

Could be your cooker, but I've had similar experiences where a good sparky had done loads of work,including CU change, months later it turned out I was there for a condition report, I found crossed ring main legs on opposite rcds, system had worked but every now and again Rcd tripped and everything had to be switched off before the rcds would reset.
dont just focus on the cooker, make sure everything is checked

 

[autocolor]

Pulled the cooker out and all connections and cables were in good order, however I did find the main cable trapped on a sharp corner where it runs behind the boiler, fortunately there was enough spare to pull through after I chased out a bit more plaster work to free it up, I stripped back the outer to see if the boiler frame had pushed right through but it was OK just a small indentation in the neutral but I guess it may have been tight enough to allow cross over especially when the boiler was hot? I have re insulated the cable for now to see if the problem still persists but if it is cured I will get the cable professionally replaced. Cooker is now on running hobs and oven so will see how long it lasts this time.
Thanks to all for your ideas, I will let you know how it goes.