Does polarity matter for an RCD?

[Steve T]

Hi all,
I recently was given an old 2 pole Legrand RCD meant for the European market but it doesn't have any indication of which side is neutral and live, and also doesn't indicate which side the supply and load go into. A picture is attached. I've looked at the data sheet which doesn't provide any info.

Does that mean the polarity is not important nor which side the supply and load go into?

Thanks for any replies!

 

[Strima]

It's marked on the device:



1 - supply line
2 - load line
3 - supply neutral
4 - load neutral

Depending on the application you have in mind for this RCD it would need to be installed in a Legrand enclosure with the correct busbar and MCBs etc.

As it is second hand I would also recommend getting it fully tested before use.

 

[Steve T]

It's marked on the device:

View attachment 87491

1 - supply line
2 - load line
3 - supply neutral
4 - load neutral

Depending on the application you have in mind for this RCD it would need to be installed in a Legrand enclosure with the correct busbar and MCBs etc.

As it is second hand I would also recommend getting it fully tested before use.

Brilliant thanks, I wasn't sure how to interpret the diagram but makes sense now.
I'm not actually planning on using it in an installation, I was just given a few European electrical bits including that rcd by a relative who's doing lots of work in their house as they know I'm interested in it.

 

[Mikegh]

Does 1 2 3 4 mean all that though

I was looking at DP MCBs similarly marked and 1 and 2 seemed to be the load side according to the way they're fitted

Obviously they're not denoting L and N on the mcb

 

[westward10]

The schematic indicates line to 1 and neutral to 3.

 

[Lucien Nunes]

The numbering shows the official assignment of line / load and L / N, you will see from the schematic that this puts the contacts upstream of the transformer and test button. However as far as AC RCD functionality is concerned a conventional non-electronic DP unit will work with either polarity and line and load in either position. All that matters to it is that the current flowing 1-2 is equal to that flowing 4-3.

 

[Mike Johnson]

Normally on Continental MCB's and RCD's the inlet side is staggered to allow neutral and phase bus bars.

 

[Mikegh]

The numbering shows the official assignment of line / load and L / N, you will see from the schematic that this puts the contacts upstream of the transformer and test button. However as far as AC RCD functionality is concerned a conventional non-electronic DP unit will work with either polarity and line and load in either position. All that matters to it is that the current flowing 1-2 is equal to that flowing 4-3.

If memory serves Hager explicitly states this

You can supply them any way top bottom right left which is handy to know

I would specifically buy Hager DP for that convenience if buying in bulk

As posters said the way protective devices are gone now you just can't take things for granted anyway

 

[Mike Johnson]

I usually buy my Hager DP from here: Electrical Wholesaler - Search - https://www.electricalwholesaler365.co.uk/search?searchtext=Hager+RCBO&searchmode=anyword

 

[brianmoooore]

What you must not do is to feed power to the top on one side and to the bottom on the other. RCD will still work fine, but the resistor limiting the current flowing when the test button is pressed will be destroyed when you push it.

 

[Mikegh]

What you must not do is to feed power to the top on one side and to the bottom on the other. RCD will still work fine, but the resistor limiting the current flowing when the test button is pressed will be destroyed when you push it.

Can you explain that thanks

I'm not getting what you mean

 

[Mikegh]

Can you explain that thanks

I'm not getting what you mean

You mean supply phase on top and supply neutral on bottom ?

That would be a rare occurrence

 

[brianmoooore]

Rare, maybe, but I came across it once. I must have been the first person to push and hold the test button, because a puff of smoke came out of the RCD, and the test button never worked again.

 

[123]

Rare, maybe, but I came across it once. I must have been the first person to push and hold the test button, because a puff of smoke came out of the RCD, and the test button never worked again.

The older contactum ones did this if my memory serves me correct.

 

[Lucien Nunes]

You mean supply phase on top and supply neutral on bottom ?
That would be a rare occurrence

I don't see how this would work at all. The entire load current would be sensed twice as an imbalance so the RCD would trip at 15mA load.

 

[brianmoooore]

I don't see how this would work at all. The entire load current would be sensed twice as an imbalance so the RCD would trip at 15mA load.

Maybe it did, but this was a 100mA RCD IIRC, so 50mA. Wouldn't be a problem with an installation in good order.
I replaced the RCD, and moved the neutral in to the top, as it should have been.