RCD issue

[Cambray]

I have an RCD which is tripping, I could not find any issues with the circuits it feeds (I turned off the C/B's that it covers) I assumed!! it was the RCD playing up bought a new one and the L and N are swopped, old one L rhs and N lhs but the new one is opposite. Can anyone tell me it it is O.K. to use either way around as it is a breaker either it is on or off and the coil for tripping is monitoring imbalance across the two. I would just need to re' mark the front face of the trip with a new set of marks.

Thanks in advance Cambray

 

[ricicle]

Unless the instructions say otherwise it won't be a problem BUT what about the outgoing side. You do not want the overcurrent protection on your neutral !

 

[ban-all-sheds]

I assumed!! it was the RCD playing up bought a new one and the L and N are swopped, old one L rhs and N lhs but the new one is opposite.

That you assumed it was faulty tells me you don't have an RCD tester, so how are you going to test the new one?

And why are the terminals different - is it not the same make/model as the old one?

Also your MCBs will be single pole, so turning them off won't do anything to remove a N-E fault, so it's quite possible that replacing the RCD won't do any good at all.

 

[Taylortwocities]

Unless the instructions say otherwise it won't be a problem BUT what about the outgoing side. You do not want the overcurrent protection on your neutral !

RCD, overcurrent protection??????????

 

[JohnW2]

Unless the instructions say otherwise it won't be a problem BUT what about the outgoing side. You do not want the overcurrent protection on your neutral !

RCD, overcurrent protection??????????

I presume that what ricicle meant was that if the RCD was wired such that the L and N got swapped, the polarity of all final circuits served by the RCD woudl be reverse, with the result that their OPDs (presumably MCBs) would then be in the neutrals.

Kind Regards, John.

 

[Paul_C]

I presume that what ricicle meant was that if the RCD was wired such that the L and N got swapped

If the RCD is replacing an existing unit, then the connections on the outgoing side would probably be determined by the busbar layout. But if you left the incoming conductors in the same places (in terms of left and right), the polarity would still be correct overall.

 

[PrenticeBoyofDerry]

I have an RCD which is tripping, I could not find any issues with the circuits it feeds (I turned off the C/B's that it covers) I assumed!! it was the RCD playing

What did you do to check that all circuits were functioning as they should?
Did you remove all loads from the RCD protected circuits, then reset your RCD?
If you did and you still had the fault, did you then proceed to do other tests on circuits, such as Insulation Resistance and RCD testing?

 

[JohnW2]

If the RCD is replacing an existing unit, then the connections on the outgoing side would probably be determined by the busbar layout. But if you left the incoming conductors in the same places (in terms of left and right), the polarity would still be correct overall.

It would indeed. I presume ricicle was concerned that the left/right might not be preserved, because of the different L/N labelling.

Kind Regards, John.

 

[ricicle]

Just to clarify, I did mean that if the incoming tail's polarity were reversed to follow the markings on the new RCD then without doing anything to the outgoing side the whole install would have reversed polarity which includes switching and overcurrent protection in the neutrals.

TTC - I hope you know me better than that !

 

[EFLImpudence]

I had to replace an RCCB recently and couldn't get the same make. The one I bought was 'the other way round'. I didn't think it mattered so fitted it and it operates as it should - but...

...why do the manufacturers mark the RCCB, i.e. give it polarity if it makes no difference?
Even the diagram printed on the device is polarised.

Untitled

• EFLImpudence
• 3 Sep 2011
• 1

Can it just be that that is the way the particular manufacturer configures their CUs or is there an electrical reason?

 

[JohnW2]

...why do the manufacturers mark the RCCB, i.e. give it polarity if it makes no difference?
Even the diagram printed on the device is polarised.

You could just as easily ask the same question about most DP switches and isolators (including CU Main Switches).

I can but presume it is done to avoid them keep being asked (and forums like this keep being asked) 'what wire goes in which terminal'.

Although it would be mechanically difficult (and senseless) to make a switch, isolator, RCD or whatever in which the positions somehow got 'swapped' (e.g. left-right) inside the mechanism, I suppose there has to be some marking to indicate which output corresponds to which input - and L & N are probably the most obvious way of doing this.

Kind Regards, John.

 

[Paul_C]

Using the pole identified for the neutral as such would be important for a 4-pole switch or RCD intended for use on a 3-phase 4-wire wye system, as in that case the contacts on the neutral pole should be arranged to make first when closing and break last when opening in order to avoid an over-voltage appearing between phase and neutral during operation.

The L & N indications on the old voltage-operated ELCB's also need to be observed, otherwise the integral test button would not work.

 

[JohnW2]

Using the pole identified for the neutral as such would be important for a 4-pole switch or RCD intended for use on a 3-phase 4-wire wye system, as in that case the contacts on the neutral pole should be arranged to make first when closing and break last when opening in order to avoid an over-voltage appearing between phase and neutral during operation.
The L & N indications on the old voltage-operated ELCB's also need to be observed, otherwise the integral test button would not work.

Agreed on both clounts - but they are not what we are talking about.

Kind Regards, John.

 

[EFLImpudence]

You could just as easily ask the same question about most DP switches and isolators (including CU Main Switches).

Yes, I had it in my mind that the Main Switch was not marked in this manner but, as you say, they are. This is obviously nothing to do with the internal workings so I shall assume the marking on the RCCB is equally unnecessary.

However, would ignoring them be in contravention of the dreaded Manufacturers Instructions regulation and be another reason for this regulation being less than ideal?

 

[JohnW2]

You could just as easily ask the same question about most DP switches and isolators (including CU Main Switches).

Yes, I had it in my mind that the Main Switch was not marked in this manner but, as you say, they are. This is obviously nothing to do with the internal workings so I shall assume the marking on the RCCB is equally unnecessary.

Indeed

However, would ignoring them be in contravention of the dreaded Manufacturers Instructions regulation and be another reason for this regulation being less than ideal?

Exactly. I'm sure that the "MI obsessed' would say (probably correctly in terms of the words of the regs) that this would be technically non-compliant. Even in terms of true safety, it would obviously be less-than-ideal since a less-than-fully-compeent/sensible person coming across an installation in which wiring was transposed relative to the product markings might conceivably get confused, and as a consequence do something silly/dangerous.

I have to admit, however, that I have 'done it' on occasions- and I don't really lose any sleep as a result. If one were concerned, I suppose one could get out a felt-tip and modify the manufacturer's markings - which might slightly improve safety, but probably not 'compliance with MI'!

Kind Regards, John.