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HappyHippyDad

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Evening all.

My customer has a series E consumer unit which has a 100mA MK RCD as the main switch. I am adding a socket to the socket circuit on this board so need to give it 30mA protection.

I happen to have a 30mA Steeple RCD for a series E CU (I collect as many different CU's as I can), but in the redundant board in my shed I notice that it was wired up with line on the left and neutral on the right. Can I just swap these around? I will still have the incoming supply on the top of the RCD but just have the line on the right and neutral on the left.

Some RCD's have contacts that open neutral last and close neutral first but i think these RCD's have L and N labelled on them, is this right? Steeple RCD's (or at least this one) does not have L and N labelled on it.

Cheers all.
 
The terminals are marked L and N and this is how it should be connected. If it does not fit the CU then it is either not compatible or it has been altered to accommodate the MK rcd.
 
I'd suggest referring to the manufacturers data sheet would be the safest way to go.

Very sensible, I shall do that Marvo, thanks.

The terminals are marked L and N and this is how it should be connected. If it does not fit the CU then it is either not compatible or it has been altered to accommodate the MK rcd.

I did say that this RCD is not labelled. I have just gone out to the shed again and checked all my other RCD's. I have another steeple which is not labelled and also the Volex RCD is not labelled, all others are (approx 8 other makes). What are your thoughts when a particular make of RCD is not labelled, would you class it as interchangable with regards L and N?
 
I'd suggest referring to the manufacturers data sheet would be the safest way to go.
Actually that's easier said than done Marvo. Where do you find the maufacturers data sheet for a Steeple RCD??! :confused:
 
I have just looked on line and there is an identical Steeple RCD (bar the rating) which has a label on it with L on the right and N on the left, see pic (steeple1) below.

Now here is the interesting bit. In the Steeple Consumer unit in my shed (see pic 'steeple2' below) the RCD that I removed was on the right hand side of the board with L on the left and N on the right (and it was wired correctly)???

Is the Steeple RCD polarity sensitive? Steeple1 (1) - EletriciansForums.net Is the Steeple RCD polarity sensitive? Steeple2 (1) - EletriciansForums.net

Would you class this as proof of both sides being able to be used as L or N? Or perhaps some Steeple RCD's are made differently? Or perhaps the board I have hasn't been wired correctly but it sure looks right!
 
Are there numbers on them?

PS there are no cables in that consumer unit, perhaps that's why it's not working?:tongueclosed:
 
Put it in it will be fine.
Usually you give pretty good advice Westward and when I see you have replied I think 'this will be correct advice'. However, I think I'll investigate a bit more unless you fancy expanding on your answer a bit? Thanks for the reply anyway.
 
RCDs operate by detecting an imbalance between Line and Neutral.
Polarity should not affect the operation of the RCD.
Correct polarity is required to ensure Line feeds the MCB busbar.
 
I've no idea where you'd find the manufacturers instructions but surely they must be available if the item is sold over the counter.....

The RCD may have a contact arrangement that ensures the neutral pole is late break / early make like a SP+N breaker. It's also possible the live pole may have positive assistance for break action which may not be on the neutral pole.

Whether or not it's suitable for reverse polarity operation depends very much on its internal design and construction....there's numerous reasons it may not be..... hence my advice stands and I'd avoid using it reverse polarity unless MI's state otherwise.
 
Steeple circuit breakers are (or were) rebadged GE circuit breakers so if you look for the GE manufacturing information it should (I say should) be comparable.
Generally I believe two pole RCDs do not have a variation in their contacts, though I would tend to follow the labelling if it is present, in its absence I would expect there should be no difference.
4P RCDs might well have a late break early make neutral and I would not attempt to swap these around.
Is the Steeple RCD polarity sensitive? GE Steeple comparison - EletriciansForums.net
Sorry about the poor photos.
 
Agree, the exception being RCDs with a functional earth connection such as MEM.
Can you explain further?
Although information is sketchy I understand that the FE is connected to the trip circuit wiring to provide a complete circuit to allow the trip to operate during a period when the Neutral is lost on the supply.
I am not sure how this would affect the operation of the main contacts, but are you saying that the trip circuit could then connect line to earth on testing or tripping?
 

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