L and N markings on front of RCD

[kingeri]

Morning all, many RCDs have N or L marked on the front of them, to indicate polarity, but just looking at a bunch of Niglon pre-populated CUs and the RCDs all have N in the top left corner on the front, which I thought meant the left terminals are Neutral, but the Neutral bar is in the right hand connector. Any ideas? Am I just being dumb?

 

[Knobhead]

It would only make a difference if the neutral was a late break contact. I could be wrong but I’m sure you only get that on 3Φ&N units. So it shouldn’t make a difference. Just looks bad.

 

[DNS1]

DIYers install them the wrong way round...

On the plus side they still work correctly...

 

[kingeri]

The thing is that they were supplied like that.

 

[Engineer54]

Morning all, many RCDs have N or L marked on the front of them, to indicate polarity, but just looking at a bunch of Niglon pre-populated CUs and the RCDs all have N in the top left corner on the front, which I thought meant the left terminals are Neutral, but the Neutral bar is in the right hand connector. Any ideas? Am I just being dumb?

Yes, whoever populated those boards have not taken any notice of the polarity of the RCD's!!

Some manufactures work from left to right on populating design layout of CU's and others right to left....

 

[kingeri]

Looks like I'm going to have to put the RCD on the left. There are only 30 of them to switch over. Should keep me busy on Boxing Day! Thanks guys.

 

[Knobhead]

If you're recovering from Christmas, it could get worse :17:

 

[Engineer54]

The thing is that they were supplied like that.

Must have been a new boy on the factory assembly line!! lol!!

The L and N designations (when provided) on protective assemblies, indicates the internal circuitry polarity, which they want you to adhere to on final installation connections...

 

[kingeri]

If you're recovering from Christmas, it could get worse :17:

Judging by the volume of family members the wife is forcing me to visit on Xmas day, I think I'd rather actually do them on Xmas Day itself......would keep me out of the way. Baa humbug.

 

[telectrix]

i would re-label them.

 

[Geoffsd]

Why are there still questions like this?
Hasn't a manufacturer got a duty to state what is safe to do with a product?

As it's AC how can it make a difference?

Is it just so that the connections correspond with the diagram on the device? - except those which don't have L & N marked.

What about if you wanted to connect the supply to the bottom terminals?
Is that ok? If so, how can the polarity matter?

 

[Engineer54]

Why are there still questions like this?
Hasn't a manufacturer got a duty to state what is safe to do with a product?

As it's AC how can it make a difference?

Is it just so that the connections correspond with the diagram on the device? - except those which don't have L & N marked.

What about if you wanted to connect the supply to the bottom terminals?
Is that ok? If so, how can the polarity matter?

It doesn't normally matter if you supply top or bottom of a typical RCD device, ( depends on the manufacturers instructions) but if you look at the small diagram on the face of RCD units you will see that it's the neutral conductor that's being monitored, not the live conductor.... To be honest i can't remember ever seeing an RCD device that didn't have the connections marked L and N... lol!!!

 

[telectrix]

It doesn't normally matter if you supply top or bottom of a typical RCD device, ( depends on the manufacturers instructions) but if you look at the small diagram on the face of RCD units you will see that it's the neutral conductor that's being monitored, not the live conductor.... To be honest i can't remember ever seeing an RCD device that didn't have the connections marked L and N... lol!!!

so what you are saying is that the L and N connections must be in the L and N terminals as marked by manufacturer, no the other way round.

 

[Engineer54]

Makes sense to me Tel!! lol!!

 

[telectrix]

does to me as well, but what has happened to the OP is ( as i read it) the CUs have been assembled with RCD on the right, when they should have been on the left.

 

[Geoffsd]

look at the small diagram on the face of RCD units you will see that it's the neutral conductor that's being monitored, not the live conductor.

No that's not right.
They are both 'monitored' like a clamp meter.

Only when there is an imbalance will the residual current be noticed.

 

[Engineer54]

does to me as well, but what has happened to the OP is ( as i read it) the CUs have been assembled with RCD on the right, when they should have been on the left.

Who knows?? lol!! To be honest i've never heard of the CU/Device manufacturer. Perhaps the OP could contact them and ask some relevant questions, ...such as why are they supplying populated CU's, with the RCD's marked Neutral connection, connected to the MCB's buss-bar?? lol!!

 

[telectrix]

that's how i see it. can't see how they are polarity conscious. as long as the current in each pole is the same ( or at least the difference is < the actual tripping current required ) then they work as meant.

 

[MDJ]

If the poles are marked wrong then either the RCds concerned are mickey mouse in quality or they are the wrong RCDs for the consumer unit, why should anyone have to re labell a RCD? just not acceptable IMO, It should be very easy for the manufacturer to get this right, another ridiculous situation here, I have never come across this, so something is amiss surely, Whats going on then?

 

[Geoffsd]

These top of the range CUs do not mark the RCDs.
As you could swap the RCDs from one side to the other the polarity can't matter.

 

[SPARTYKUS]

You could rig one up, run the suite of tests, then change polarity & run them again. And then see if it behaved any differently!

 

[Engineer54]

No that's not right.
They are both 'monitored' like a clamp meter.

Only when there is an imbalance will the residual current be noticed.
View attachment 16327

That is basically a simplified illustration diagram. If you get the chance, open up a duff unit your going to bin and check the actual internal arrangements...

Well the question to answer then, is Why would the manufacturers bother to mark connection posts?? They wouldn't mark if their was no reason, that would be a cost loss... lol!!

 

[MDJ]

These top of the range CUs do not mark the RCDs.
As you could swap the RCDs from one side to the other the polarity can't matter.

View attachment 16328

Geoff, I can't remember seeing an RCD with a marking on a pole, what make is that Bud?

edit I now see it is Volex, never used one of those TBH

 

[Engineer54]

These top of the range CUs do not mark the RCDs.
As you could swap the RCDs from one side to the other the polarity can't matter.

View attachment 16328

What!! .....Since when has Volex been classed as ''Top of the Range''?? Always been firmly in the Budget bracket range... lol!!

 

[MDJ]

yep agree with E54, infact bargain basement stuff LMAO

 

[Geoffsd]

Sarcasm is wasted on this forum :willy_nilly:

 

[Engineer54]

Geoff, I can't remember seeing an RCD with a marking on a pole, what make is that Bud?

edit I now see it is Volex, never used one of those TBH

Just remembered i have 3 makes of RCD in the car (Contractors submitted samples) , so i've braved the rain to go check myself. ...Hager, Gweiss and Aoelec, ....All three have the L and N marked top and bottom..

 

[Geoffsd]

So, Engineer hasn't seen RCD without LN markings and MDJ hasn't seen one with.

 

[SPARTYKUS]

Volex...... Fisher Price

 

[MDJ]

Just remembered i have 3 makes of RCD in the car (Contractors submitted samples) , so i've braved the rain to go check myself. ...Hager, Gweiss and Aoelec, ....All three have the L and N marked top and bottom..

I meant without a marking, sorry fella, was agreeing with you this time, typing too fast and not looking properly haha

 

[MDJ]

So, Engineer hasn't seen RCD without LN markings and MDJ hasn't seen one with.

no I typed wrongly, I agree with engineer this time, another question, whats best, volex steeple or proteus , hmm a toughy that

 

[Engineer54]

Well, ...i think i'll stick with connecting such marked devices (of any description) as indicated by the manufacturer. You lot can do as you please!! lol!!

 

[Geoffsd]

The Volex RCDs don't have markings.

I suppose because one is on the left and one is on the right but I would think they are the same inside.

 

[MDJ]

I believe you Geoff, I have never seen a volex RCD, I gave up on volex after seeing the range of kit they make, appalling, they should be banned here haha

 

[Engineer54]

The Volex RCDs don't have markings.

I suppose because one is on the left and one is on the right but I would think they are the same inside.

How do you think other manufacturers CU/RCD's work then, having the same arrangement as your top of the range Volex? eg, ...2 RCD's one on the right and one on the left?

 

[1shortcircuit]

I crossed this issue today funnily enough.

Existing board where so numpty had swapped the RCCB device out for a MAIN SWITCH. Due to the configuration of the board and length of existing cables etc I had no option but to label the tails and both RCCB units up. Tails entered the board on the right but labeling on the RCCB device indicates that the board should have had the tails enter from the left.

Testing of the devices afterwards proved that they still operated as intended and a MAIN ISOLATOR has been installed in front of the board.

Square D Domae

 

[SPARTYKUS]

Got a crabtree board to go back too after chrimbo, split load, BUT the 80A RCCB is off, taped up. All circuits still fed through it!!!


Neutral bars linked. Can't wait to have a look what some bodger has come up with. And then of course discover & resolve the fault that stumped them

 

[telectrix]

well, if it's in shropshire, it's probably been installed by a conservative MP or a horse. if it smells of sh*t, it's the former.

 

[SPARTYKUS]

Its one of thoses houses that had the full treatment; take the light fitting down in the kitchen to find a fist sized hole and the old rose pendant shoved into the void, flex conn'd to the new light.

 

[yellowvanman]

That is basically a simplified illustration diagram. If you get the chance, open up a duff unit your going to bin and check the actual internal arrangements...

You've now intrigued me. It was my belief that an RCD works on the balance/inbalance of current in and out. ie. the sum of current through Line(s) and Neutral = 0. If you say only one is monitored how does it monitor the inbalance?

At the moment haven't got an old RCD to butcher!

 

[SPARTYKUS]

You've now intrigued me. It was my belief that an RCD works on the balance/inbalance of current in and out. ie. the sum of current through Line(s) and Neutral = 0. If you say only one is monitored how does it monitor the inbalance?

At the moment haven't got an old RCD to butcher!

I've got one...might set about it later

 

[Engineer54]

You've now intrigued me. It was my belief that an RCD works on the balance/inbalance of current in and out. ie. the sum of current through Line(s) and Neutral = 0. If you say only one is monitored how does it monitor the inbalance?

At the moment haven't got an old RCD to butcher!

My mistake yellowvanman, trying to squint looking at the diagram in the face of a budget RCD, and it's basically only a simplified diagram lol!!

Yes your correct on the balance/imbalance thing, but i'm pretty sure that there is a very good reason why they are polarised by the manufacturers. we'll just have to wait and see what Spartykus comes up with when he opens his duff unit up (with photo's hopefully)!! lol!! Might even get the contractor here to open an old MG unit, when i go back after the company Xmas trip...

 

[Stroppy]

The sensing coil couldn't possibly be 'measuring' one conductor only, what would it be comparing it against to get its trip current?

 

[MDJ]

Well IMO actually at the very least connecting the correct conductors to the identified poles is at least good practice, too much crap on here, any spark I employed connecting a neutral to the marked L connection on an RCD would get an early bath, regardless so there, if the RCD won't connect to the board you have then buy one that will, My god my Mentor would roll in his grave if I didn't consider the correct connections to the marked poles, too much Bull Sh*t today, get a grip and do the job right FFS