rccb tripping (regularly with new oven)

[salisbury spark]

Customer had comet install a (12kw)standalone commercial cooker. RCCB trips 90% of the time when oven switched on (2kw oven)and also while oven operating. (hob is fine). Cable is 6mm on a 40amp mcb which needs sorting (should be 32a mcb on 6mm says BRegs) and should uprate to 10mm cable(due to load). But why is rccb tripping so much (40a mcb not tripping) either intermitent fault in oven or rccb to sensitive. Dont rate rccbs, prefer rcds. - Do you recommend trying a RCD or most likely a oven fault?- need help of an experienced electrician (cirrus r u out there)....all advice welcome.

 

[eskimo39]

Hi Sailsbury. Just to inform you I am not a qualified electrician yet but have been doing lots of revision on fault finding for my exams.

I have read quite a few articles about heating elements in ovens containing water when new which can cause earth leakage problems. I don't really know how to check this but have read that some electricians bypass the protection to run the oven for an hour or so to dry out the element.

If it is an earth leakage fault this could explain the mcb not tripping!!! Hope this helps.

Can anyone on here confirm this????

 

[Dazza1976]

When i did my City and Guilds course, my tutor who had some 30 years + experience told us not to put an oven circuit on rcd, because of nuisance tripping, because of earth leakage from the elements in an oven, like Eskimo was saying.
However with the 17th edition updates, they say that ever new circuit installed now, should be protected by rcd. So im not sure where we stand with this now. Does the customer just have to bare the inconvenience of resetting their rcd every time it trips with the oven on ??

 

[WarrenG]

Customer had comet install a (12kw)standalone commercial cooker. RCCB trips 90% of the time when oven switched on (2kw oven)and also while oven operating. (hob is fine). Cable is 6mm on a 40amp mcb which needs sorting (should be 32a mcb on 6mm says BRegs) and should uprate to 10mm cable(due to load). But why is rccb tripping so much (40a mcb not tripping) either intermitent fault in oven or rccb to sensitive. Dont rate rccbs, prefer rcds. - Do you recommend trying a RCD or most likely a oven fault?- need help of an experienced electrician (cirrus r u out there)....all advice welcome.

Are we talking a 12kW or a 2kW oven? Its a big difference.

 

[salisbury spark]

12kw total load including 2kw oven. - funny enough i told customer that new ovens will have moisture in them and will trip until dried out..... - Takes customer over 4hours to cook a simple meal in oven because of tripping. - Not really an acceptable excuse as ovens cook in moisture all the time... Customer skint at moment but will go back and another look thanks for everybodys input. TBC......