CK Tools :) The professionals choice when it comes to Electrical Tools
This official sponsor may provide discounts for members

Discuss tripping help!!! in the Industrial Electrician Talk area at

Welcome to - The American Electrical Advice Forum
Head straight to the main forums to chat by click here:  American Electrical Advice Forum

I have just put a new 10way plitboard in my friends house after the old rewireable fusebox and wiring melted back to the main switch. I have put the 2 lighting circuits on 6a mcbs and the shower, and two ring final circuits in 40a mcb and two 32a mcbs on the rcd protected side, now as soon as i switch on either ring or shower circuits it trips the rcd. After asking my friend about the sockets he said there was a problem before and he thinks they joined to two ring final circuits together somewhere! I have tried continuity tests and everything seems fine, i couldnt do any live tests as it trips when i look at it!! help please anyone


if he suspects the 2 rings are connected then something is telling him they are so they probably are!! not sure about 40a mcb protecting one of the rings either....

you sure the shower isnt causing problems as well?? disconnect the shower neatral and try resetting rcd, if it changes nothing then its not the shower...

if the 2 rings are connected then dropping neatrals arnt gonna help, think your gonna have to go round and drop some front plates off and try and find this offensive wire. if he thinks they are connected then ask him where some one was working before for clues as to which socket is the culprit..

sure others will be adding some more to this and probably correcting what ive put!!

might of been good to test before doing the job as well!, heinsight is a wonderful thing!! lol

just a thought as well but if you do the full 3 stage ring final test then that might help you locate the problem a bit easier??
Last edited:
  • Thread Starter Thread Starter
  • #3
thanks for your quick reply, a bit more information to help clear things up, the shower is on a 40a mcb and the two ring final circuits are on 32a mcb. AFter speaking to my friend he thinks the circuits were connnected about 4 years ago. this does not explain why the fuse box melted last night? hope this helps many thanks


To be honest, you should have carried out substantial testing before connecting up to the new cu, as this may have given a clue as to where/what the problem may be.

The tripping could be caused buy a number of things.

1- cables in shower isolator could have been bent beyond safe radius, causing heat build up.
2- screws piercing cables behind socket (most common).
3- as stated, neutrals crossed in cu. Some cu's require you to remove a link to separate the neutral bars.
4- faulty electric shower.
5- faulty appliance plugged in.
etc etc.

IR tests are a good place to start.

Whatever it is, good luck, as you are going to need it. especially with this type of fault.
Last edited by a moderator:


Are the insulation resistance results ok, also are ring final neutrals connected into neutral block on rcd side in DB
  • Thread Starter Thread Starter
  • #6
the neutrals from the rcd side are not in the neutral bar on the rcd side could that be the cause?


the neutrals from the rcd side are not in the neutral bar on the rcd side could that be the cause?

BUT, you should still go back and do a proper test on the whole install.

Also, the cu that you installed is not to current regs.

Last edited by a moderator:


Without seeing the beore and after the following comes to mind.

What was the original fusing on the shower circuit, bad connections on shower circuits can create sustancial problems and will cause some heat damage (how many pull switches have we seen melted internally where the connections were not made properly?)

If the heat damage is as bad as you said disconnect the three suspect circuits and test for continuity between live/ earth and neutral/earth. (make sure nothing is plugged in to any sockets). If you get continuity showing you may find that there is heat damage to the inner insulation of the cables. Before you reconnect try an insulation test to make sure.

This will hopefully iliminate one possible cause.

It then comes down to physically checking the sockets, every connection and every cable, but if the fault is that severe consider rewiring the offending circuits, it might be quicker in the long run.


still doesnt explain the meltdown???
No it doesnt, and i have to say that, although the new cu is 'safer' i would still be back first thing to investigate.

If the meltdown started in the old wylex then i would probably put it down to loose connection.

It sounds as if the house has had a fair bit of diy.


the most damage ive personally seen was from a poorly connected neatral bar link at a consumer unit, whole side of a hagar board went all squishy


When under the influence of hallucinogens I find it is always good practice to remain in the company of trusted friends who are on the same 'wavelength'. Not only does this ensure a fun time by all but can also minimise the possibility of a 'bad trip'.

Personally, I also found magic mushrooms to be a bit too intense for me when taken in copious amounts and brewed. Start little and remember:

"You CAN'T fly"
  • Thread Starter Thread Starter
  • #14
tripping help update
Well today i tested the whole system and talked to my friend, The shower is conncted to the cooker circuit in 6mm, there is no cooker connected!
I had put the neutrals from the rcd side in the wrong neutral bar
when i tested the circuits everything was ok but the downstairs ring final was down a bit doing the insulation resistance
phase/neutral - 61M ohms
phase/earth - 55.5M ohms
earth/neutral - 3.69 M ohms

end to end
phase - 0.48 ohms
neutral - 0.51 ohms
earth - 0.78
The person who lived there before was an avid diy er he put the shower in and numerous spurs some even appear to come from upstairs!
anyway job done I'm not doing anymore like that for a pint!


anyway job done I'm not doing anymore like that for a pint!

uttered a thousand times !!!!!!!!!!!
Bulk Workwear - Clothing Suppliers for the Whole Forum Network
This official sponsor may provide discounts for members

Reply to tripping help!!! in the Industrial Electrician Talk area at

uHeat Banner - Forum Discount Available
This official sponsor may provide discounts for members
Top Bottom