Rcd Test Switch and circuit not working

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I understand what you're saying with a neutral to earth short. Of course, the trip switches only switch out the live. So need to take the n-e fault or of the equation. Will need to power all down and unwire the cooker properly before trying again.
Indeed.
Maybe the rcd isn't broken after all
Yes, possibly, but I'm not convinced that would necessarily be 'good news' for you - since replacing an RCD would probably be simpler (and cheaper) than repairing a cooker, and certainly cheaper than replacing a cooker.

Let us know what you find!

Kind Regards, John
 
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Will do, thanks John.
Will try tomorrow.
I suspect the cheap replacement cooker element. Maybe that caused a n-e fault.
May have to change the rcd too then if that fit destroyed too.
Will see.
Cheers again
 
OK fellas, got an update.
Disconnected the cooker entirely.
Still had same issue where the rcd wasn't resetting and giving power to the circuits.
Powered down the consumer unit and looked inside and saw the problem.
At the bottom of the rcd where a bar connects the rcd to the first of the breakers (which happens to be utility room ring circuit) you can see melted plastic.
I'm guessing that there was some arcing going on due to either the rcd or breaker not being tightened down enough on the connecting bar.
Had this problem with one making an arcing noise a while back which I fixed by tightening.
Looks like I need a new MK5780s 80A 30mA rcd and a MK LN 5932s breaker.
Only problem is that my local screwfix doesn't sell these exact models.
I found other brands that do a variety of 80a 30mA models but want to get the correct equivalent.
Any idea what the screwfix equivalents would be?
Thanks
 
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For those that are interested, here's a couple of pics. Note the melted plastic in the underside photo.
 

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For those that are interested, here's a couple of pics. Note the melted plastic in the underside photo.
Thanks. In exchange, this is what happens inside an RCD if it 'goes bang' :) ...

upload_2021-4-8_19-9-0.png


Kind Regards, John
 

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That's pretty John. Bet that smelt too...
It was all over in a fraction of a second. after which the DNO fuse blew - but the initial' bang and puff of smoke' was apparently quite dramatic.

As I reported here at the time (a good few years ago), it happened when my daughter pressed the RCD's test button and, in the course of tripping in response, the trip mechanism chopped through one of the live conductors! Given that periodically testing RCDs is a good idea, I have been trying ever since to talk her out of the "never again" attitude to RCD test buttons she had had since then!

Kind Regards, John
 
Will either of these do the job to replace the RCD MK5780s?:

British General 80A 30mA DP Type AC RCD (86998)
Eaton Memera 80A 30mA DP Type AC RCD (857FX)

and for replacing the MK LN 5932s B32 would these do :

Chint 32A SP Type B MCB (3365V)
Schneider Electric Easy9 32A SP Type B MCB (8402P)
Crabtree Starbreaker 32A SP Type B MCB (90391)

Can't get direct MK replacements from Screwfix
Any preferences?
 
Cast your purchasing net wider-TLC list the rcd. Mixing brands in 1 box isn't wise, there tend to be subtle differences in terminal heights which lead to potential distortion of the bus bar and overheating/device failure. And there's the whole type-approval issue as well...
 
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Good point. Didn't think about that.
So good to stick to mk then
Thanks
 
Cast your purchasing net wider-TLC list the rcd. ...
They do, albeit they list it as "Discontinued" (see bottom right of below) :)

upload_2021-4-8_20-22-12.png


Mixing brands in 1 box isn't wise, there tend to be subtle differences in terminal heights which lead to potential distortion of the bus bar and overheating/device failure. And there's the whole type-approval issue as well...
All true. It's possible that the modern MK equyivalents (albeit no longer made by MK) are compatible - maybe they could tell you?

Kind Regards, John
 
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The one in the picture looks a bit different to my one. Maybe a different issue of the same model.
Am keen to get the parts tomorrow after work so I can fix tomorrow night. Don't really want to wait for mail order as that will be next week sometime and my wife is already getting stressed not having the oven.
Would the screwfix equivalents be that bad?
If OK, which of the equivalent screwfix brands would you go for?
Thanks
 
@JohnW2 oops, my bad- after wading through a load of watch adverts i stopped at the headline listing.
@WSB your consumer unit has been tested & found to comply with regulations, legislation etc. when the innards are of the specification set out by the manufacturer. Use of alternates would void that approval & possibly land you in bother if you suffered an electrical fire (would give the insurer a very easy out). Talk to MK. And/or take a ruler and the old rcd to Screwfix, make sure critical dimensions of your temporary replacement are within a mm or 2 of the MK.
 

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