Is This A RCCB Fault?

[action jackson]

Good evening all!

I have discovered this evening (whils't re-setting the RCD) that when applying light pressure to the RCCB in my Crabtree Starbreaker CU, the connection into the busbar arcs severely and all circuits on this side of the CU flicker.

I have tried re-seating the RCCB but has made no difference.

About a year ago i replaced the busbar for a different configuration to allow the fitment of a RCBO.

Is it likely the RCCB contacts are damaged or is it likely the terminals in the busbar are worn?

On a side note, is it acceptable to have a 63 amp rated RCCB supply 3 x 32Amp MCB's?

 

[GLENNSPARK]

right then mate....you need to check that the termination clamp on the RCCB is actually clamping the fork on the busbar.....and the fork isn`t just sat BEHIND clamping plate....(it will become obvious when you look)..... as it sounds like this is what has happened here mate

 

[GLENNSPARK]

if this is the case...it will need sorting out sharpish as theres a real risk of overheating here.......

 

[action jackson]

right then mate....you need to check that the termination clamp on the RCCB is actually clamping the fork on the busbar.....and the fork isn`t just sat BEHIND clamping plate....(it will become obvious when you look)..... as it sounds like this is what has happened here mate

cheers mate. I guess i need to do this with the RCCB in situ but i dont have much room to see...

 

[GLENNSPARK]

well 2x 32A=64A....put it this way....you`d be lucky to pull that for a small 2 bed house mate (as long as someone didn`t have everything on at once including a heated shower)...lol....so i wouldn`t worry about those 32A MCBs on that RCD mate...lol....

 

[GLENNSPARK]

cheers mate. I guess i need to do this with the RCCB in situ but i dont have much room to see...

much rather you did this with a good torch and clear the area you need to work in....all the work you need to do in the c/u AFTER you kill the power and do a safe isolation wont you.....as you will need to loosen the busbar....dont forget to undo the terminal clamp FULLY will you on that MCCB.....this will ensure that the busbar fork sits within the terminal clamp.....the same for the MCBs mate....

 

[action jackson]

well 2x 32A=64A....put it this way....you`d be lucky to pull that for a small 2 bed house mate (as long as someone didn`t have everything on at once including a heated shower)...lol....so i wouldn`t worry about those 32A MCBs on that RCD mate...lol....

Its 3 x 32A MCB's on the RCCB mate.

I have dissconected everything but the necessities on the RCCB side and will swich off when i go to bed!

Will have a quick look now and see if i can see if the clamp is in the right position.

 

[GLENNSPARK]

whenever fitting busbars into C/Us....it pays to unscrew the terminations on MCBs/RCDs/RCBOs fully as it shouuld eliminate the issue if getting busbar forks the "wrong side" of terminal clamps.....and dont forget also when working stranded conductors (tails) into position..it always pays to give em a last nip up before replacing C/U cover.....can work loose can strandeds with just a little movement/manipulation....

 

[GLENNSPARK]

do away with that 63A RCCB and stick an 80A in mate.....doubt you would get up to the max capacity ov it but with 3 x 32A MCBs on it....theres always the risk as that will be quite a large amount of the house demand there.....

 

[action jackson]

Just to point out mate, my CU has the plug in style bus bar, not the strip busbar....

 

[GLENNSPARK]

Just to point out mate, my CU has the plug in style bus bar, not the strip busbar....

now you say!!..lol....well is it plugged in correctly?...you can remove the RCCB and check the condition of the spade/plug in termination.....look for signs of overheating..damage etc...

 

[action jackson]

now you say!!..lol....well is it plugged in correctly?...you can remove the RCCB and check the condition of the spade/plug in termination.....look for signs of overheating..damage etc...

Yes its plugged in correctly and i have removed and fitted a few times with no improvement. The spades appear fine however the input spade does have the slightest sign of overheating (i suspect it was caused when i foundthe fault by applying pressure to the RCCB)

 

[soulman]

Change the busbar mate had a similar fault with a starbreaker before xmas. Try & put a bit of contact cleaner on and make sure it is pushed fully home. In november had to change both rcd's and busbar in another starbreaker ccu. 100ma time delayed front end & 30ma rcd both were goosed. Already had two 30ma rcd's in my spares bucket so purchased a new configuration busbar & changed to split board with main switch & two 30ma rcd's. what a pain i'm not keen on these plug in boards. For the price of busbar and rcd i would be tempted to change the board.

 

[GLENNSPARK]

i think there a stupid idea these things....like trying to reinvent the wheel or summat......yet more evidence that the older forked type busbar (fitted correctly) is the better way than this fad.....

 

[action jackson]

The busbar is only a year old!

 

[GLENNSPARK]

well i know you can get replacement busbars for em....in different configurations n all...but i dont have that much experience of em...and as soon as i saw one i didn`t like it.....could see problems looming over the horizon with it then....had a load of MCBs and c type RCBOs for these...sold em to my boss...lol...i didn`t want the damn things as i wouldn`t fit this...

 

[Knobhead]

Read the O/P’s previous posts. Then tell him where to go

 

[MarkieSparkie]

I've only seen this occur once in 30 years of fitting Starbreaker consumer units, maybe I've just been lucky.
A while ago I had a single contact on a Starbreaker busbar arcing and suspected a manufacturing fault, I returned the busbar and RCD to Electrium (Crabtree's parent company) for investigation. They replaced the parts unconditionally by return of post. I urge you to do the same.
This maybe stating the obvious, but I feel it in the circumstance it's worth pointing out that it's vital not to force spare cable/conductors (overcrowding) behind plug-in RCDs, RCBOs, MCBs and other accessories as this may stop the device from fully seating or skew the mating contact(s). This is important when terminating Neutral fly-leads, particularly when retro-fitting a number of adjacent RCBOs.

 

[MarkieSparkie]

i think there a stupid idea these things....like trying to reinvent the wheel or summat......yet more evidence that the older forked type busbar (fitted correctly) is the better way than this fad.....

Crabtree's motivation for using this method was to:
a) Reduce the chances of mixed manufacture devices being used in their consumer units and thereby invalidating the assemblies BS EN 60439-3 type testing and guaranteed 16kA fault withstand.
b) Provide better protection of the live busbar.

 

[action jackson]

I've only seen this occur once in 30 years of fitting Starbreaker consumer units, maybe I've just been lucky.
A while ago I had a single contact on a Starbreaker busbar arcing and suspected a manufacturing fault, I returned the busbar and RCD to Electrium (Crabtree's parent company) for investigation. They replaced the parts unconditionally by return of post. I urge you to do the same.
This maybe stating the obvious, but I feel it in the circumstance it's worth pointing out that it's vital not to force spare cable/conductors (overcrowding) behind plug-in RCDs, RCBOs, MCBs and other accessories as this may stop the device from fully seating or skew the mating contact(s). This is important when terminating Neutral fly-leads, particularly when retro-fitting a number of adjacent RCBOs.

Did you find out if it was the busbar or RCD causing the fault?

I will contact Crabtree first thing tomorrow however i can't wait for them to test my parts and replace etc etc. I obviously need to get this rectified ASAP for safety reasons!