3 63 amp RCDs on same circiut

[king_11]

2 are in the board and the other is feeding that which is also being fed from a 100 amp rcd. cant seem to find any problems with cables and does just nuisance trip.

help plz

 

[nickblake]

will need some more info as its a bit sparse what are the miliamp ratings of the RCD are they time delayed and what installation methods have been used for the cabling that the RCD's are supplying

 

[king_11]

not time delay...all 30 ma ... 10mm swa in whole install

 

[tony mc]

Still need some further info.

Nuisance tripping what is tripping?

Is the 100 mA RCD a S or time delayed as if it is not you will possibly have no discrimanation !

 

[Edd]

yer a lil confused as to what your discribing,, as others say a lil more info is needed. and im sure someone here can help

 

[king_11]

Still need some further info.

Nuisance tripping what is tripping?

Is the 100 mA RCD a S or time delayed as if it is not you will possibly have no discrimanation !

They are all tripping sometimes it's just 63 but other times the 100 will go as well. No it's not time delayed

 

[Edd]

whats the layout of the board and circuits, sounds like a bad setup with disgrimanation between RCDS, can you discribe the layout more or poss pics?

edit,, sounds like you also may have a fault that needs to be found as well

 

[nickblake]

So what you are saying is you have 100 amp RCD feeding 2 63 amp RCD's or you have 100 Amp RCD feeding a dual RCD board ,if this is the case what earthing arrangement do you have , what installation methods is the 100 amp RCD suppling the 63 amp RCD's answers to these questions will help us give you the answer you are looking for sorry to be a pain but the more info you give the better the advice

 

[king_11]

whats the layout of the board and circuits, sounds like a bad setup with disgrimanation between RCDS, can you discribe the layout more or poss pics?

edit,, sounds like you also may have a fault that needs to be found as well

100 amp feeding a 63 amp under board the feeding a dual Rcd board.

 

[tony mc]

Sorry to go on King 11

I cant make sense of this.

Have you a photo as it no looks like 4 RCD 's are connected.

 

[Edd]

100 amp feeding a 63 amp under board the feeding a dual Rcd board.

hmm as others keep saying, im a lil lost as well.. your saying 100 amp feeding 63 amp and then a duel rcd board? are you meaning to say... A 100amp 30ma RCD feeds a 63amp 30ma RCD then goes off to a duel 30ma RCD board? If you are then the whole install is inaproprate and needs looking into, we will then need to know more about the setup to see if any distribution circuits can come off RCDs to stop the problem...
also to dig deaper, is it a TT system?

 

[king_11]

hmm as others keep saying, im a lil lost as well.. your saying 100 amp feeding 63 amp and then a duel rcd board? are you meaning to say... A 100amp 30ma RCD feeds a 63amp 30ma RCD then goes off to a duel 30ma RCD board? If you are then the whole install is inaproprate and needs looking into, we will then need to know more about the setup to see if any distribution can come off RCDs to stop the problem...
also to dig deaper, is it a TT system?

yes that's exactly what I'm saying. I'm not sure if it's tt it's a possibility !

 

[nickblake]

So 100 amp RCD feeding a 63amp RCD feeding a dual RCD board , or is it 100 ma RCD feeding a 63 amp RCD feeding a dual RCD board is the install TNCS , TT ,or TNS

 

[nickblake]

TNCS where the earth is linked to neutral often internally with a block off the side of the cut out , TT uses and earth rod ,TNS where the outer sheath is used as the earth If its a TT supply then you will only need the dual RCD board unless its metal clad where you will need a 100 ma or 30 ma time delayed RCD we could do with a picture so we can offer the correct information

 

[alarm man]

sounds like a tt,100ma as main switch,not sure what the 63/30ma inbetween is doing then to the cu,serious leakage all the same

 

[Edd]

2 are in the board and the other is feeding that which is also being fed from a 100 amp rcd. cant seem to find any problems with cables and does just nuisance trip.

help plz

how long has this been setup like this? is it a new install? the setup seems a bit problematic and not thought through.. if its an old install i would be getting th IR tester out... if new i would be getting the install sparks out!

 

[king_11]

It's defo not 100 ma. It's 100 amp. It is the main switch to a 3phase board and one phase goes below to a 63 amp with 45 amp breaker like a mini board . The that goes to a dual Rcd board

 

[alarm man]

how long has this been setup like this? is it a new install? the setup seems a bit problematic and not thought through.. if its an old install i would be getting th IR tester out... if new i would be getting the install sparks out!

ot it could have been installed by a spark with a fear of electric shock..

 

[king_11]

how long has this been setup like this? is it a new install? the setup seems a bit problematic and not thought through.. if its an old install i would be getting th IR tester out... if new i would be getting the install sparks out!

It's new . Last year . Yeah seems they have messed it up. It's been like this awhile but the install has never been used properly just now and then

 

[nickblake]

with out looking at it its so hard to see what you have like i have already said a Picture paints a 1000 words

 

[Edd]

thought I had the install setup in my head,, but im missing things?? 100amp 3 phase main swith with no RCD that sound normal? to a 63amp with 30ma rcd? which is where? off to a duel board... sorry im not getting it now.. dont get frustrated kay, but a few pics may really help here as your termnoligy seems a lil off m8,, in the politest manour..

ps my spelling seems to suck

 

[king_11]

thought I had the install setup in my head,, b ut im missing things?? 100amp 3 phase main swith with no RCD that sound normal? to a 63amp with 30ma rcd? which is where? off to a duel board... sorry im not getting it now.. dont get frustrated kay, but a few pics may really help here as your termnoligy seems a lil off m8,, in the politest manour..

ps my spelling seems to suck

can't seem to upload pics.

100 amp is Rcd mate. To a 63 Rcd below board and then off to a dual Rcd.

 

[Octopus]

I think the only way forward would be a couple of pictures ... and what test equipment do you have at your disposal?

 

[king_11]

I think the only way forward would be a couple of pictures ... and what test equipment do you have at your disposal?

Fluke multimeter

 

[Des 56]

2 pages of compressed descriptions of the install and questions on that set up in each post,my eyes ache

 

[Edd]

so we got a 100amp 30ma rcd at the front end (3 phase)( thats a pain in the butt too start with),, if this is so then get rid of the others, their not needed.....wonders why they were fitted.. if its not tt then get rid of the front end rcd and use rcbos for the circuits that req rcd.... sorry if im not more helpfull...

 

[alarm man]

Fluke multimeter

decent meter fluke,you may need more than that tho

 

[king_11]

so we got a 100amp 30ma rcd at the f ront end (3 phase)( thats a pain in the butt too start with),, if this is so then get rid of the others, their not needed.....wonders why they were fitted.. if its not tt then get rid of the front end rcd and use rcbos for the circuits that req rcd.... sorry if im not more helpfull...

ok that's what I was thinking . I can take the rcds out and just use the main switch as isolation in dual board

 

[king_11]

Yes it is tt.

 

[Edd]

sorry went to bed!,, If its TT then the RCDs are required, but not all of them I would be looking at trying to remove the 3 phase RCD and fit a main switch then fit rcbo's to final circuits that are fed from the 3 phase board, and an MCB to feed the other RCD protected board..hopefully there aint many ways on the 3 phase board. at least this spreads the loads and any faults will trip the approprate RCD.

 

[king_11]

sorry went to bed!,, If its TT then the RCDs ar e required, but not all of them I would be looking at trying to remove the 3 phase RCD and fit a main switch then fit rcbo's to final circuits that are fed from the 3 phase board, and an MCB to feed the other RCD protected board..hopefully there aint many ways on the 3 phase board. at least this spreads the loads and any faults will trip the approprate RCD.

okay I've changed a few things around today ... I've taken out the Rcd below board . I've notices as well it seems to trip when it gets a surge of current ie printer or hand dryer. The 3phase braker is an old mem one so could be a problem changing that

 

[Octopus]

I've notices as well it seems to trip when it gets a surge of current ie printer

Cripe, where are you? Wapping?

 

[Edd]

Do you have an IR tester? as what you are discribing could well be an underlying low resistance that on its own is not enougth to cause a tripping situation, but when a suden increase in load is seen it unbalences the RCD. (this is very common)

 

[king_11]

Do you have an IR tester? as what you are discribing could well be an underlying low resistance that on its own is not enougth to cause a tripping situation, but when a suden increase in load is seen it unbalences the RCD. (this is very common)

I have s fluke multimeter yeah . What's the best way of sorting it ? Remove Rcd?

 

[Octopus]

I have s fluke multimeter yeah . What's the best way of sorting it ? Remove Rcd?

Removing the RCD may cure the "pain" for the client but is not the way to find andfix the fault. Have you IR'ed anything?

 

[king_11]

Removing the RCD may cure the "pain" for the client but is not the way to fin d andfix the fault. Have you IR'ed anything?

I know your right but the customer has also ask me to do this . I have not no

 

[gottahugenoggin]

I know your right but the customer has also ask me to do this . I have not no

If faced with a fault on a circuit where the CU has rewireable fuses and the the customer asks you to replace the fuse wire with a nail would you do it?
If the fault is on the circuit then the RCD's only doing its job.You'd be removing the protection not the problem
Is it a multimeter or a multifunction tester you have?
The best way for these guys to help you out would be to post some pictures and give as much info as possible,what tests you've carried out and the results

 

[Edd]

sry King11 but without an IR (insulation resistance) tester finding the underlying fault is gona be almost imposible, and time consuming, at best your gona be guessing.. And as the others have said dont remove the RCD just because the cliant has asked, it WILL be your arse on the line.

 

[Octopus]

sry King11 but without an IR (insulation resistance) tester finding the underlying fault is gona be almost imposible, and time consuming, at best your gona be guessing.. And as the others have said dont remove the RCD just because the cliant has asked, it WILL be your arse on the line.

I noted my comment about IR tested went unanswered.... may be it will now.

 

[tony mc]

What you don't want is the next call being to the fire service once the RCD is removed!

I wonder who the client would blame when they insist they know nothing about electrics and RCD's stating that why they contacted a electrician!

A RCD trips for a reason and that need to be established or walk away from the job IMO!

 

[malcolmsanford]

did we ever do a ramp test ........................I'll get my coat

 

[Knobhead]

i know it wouldnt leave the install like it permentaly they really need to use the install so it would only be temp if i did

On your head be it!

 

[Rockingit]

SO many unanswered questions on this, or questions that need to be asked. Have you considered getting another sparks in to do this one on your behalf? You sound a little out of your depth.

 

[king_11]

okay think ive found the faulty circuit, i did IR and got 223 on E - N and L - N }500 set on 500v. its a light cicriut 1.5mm

 

[UNG]

okay think ive found the faulty circuit, i did IR and got 223 on E - N and L - N }500 set on 500v. its a light cicriut 1.5mm

223 & 500 what Ω or MΩ

I think you need to consider involving some one with a little more knowledge than yourself in the best interests of all concerned

 

[king_11]

MΩ. Fault has gone. ive isolated that circuit

 

[emc]

Sounds like a non sensicle installation. 100A RCD feeding 63A RCD all 30mA instant... Why? you have discrimination issue immediately. The second MCB seems to serve no purpose - could just be a MCB.

 

[Rockingit]

200 odd MOhms is a perfectly acceptable value, so not sure how you can claim that to be the fault when clearly so many other issues seem to exist. Do the maths, and you'll see why it's not going to be an IR value of 200M that's causing a 30mA RCD to trip.

 

[king_11]

Do you have an IR tester? as what you are discribing could well be an underlying low resistance that on its own is not enougth to cause a tripping situation, but when a suden increase in load is seen it unbalences the RCD. (this is very common)

Correct! You know your stuff mate! #cheers