Difference between 1p+N and double pole RCD

[HappyHippyDad]

I need to replace a Hagar RCD (model number CN284U). This is a type AC RCD and I wish to replace it with a type A.

The model number for the Type A equivalent is CNA584U.

They are both 100mA, 100A, S type.

The only difference being is that the Type A RCD is referred to as 1P + N rather than double pole. I'm getting a bit confused by the difference?
I thought the +N meant that the N is just switched off when there is a fault but doesn't actually detect the fault itself.

What is the difference between a double pole RCD and a 1P + N RCD? With both types of RCD the phase and neutral become open if a fault is detected, so it must relate to where the fault is detected (i.e phase or neutral). Or.. it is just different terminology meaning the same thing?

 

[Risteard]

I need to replace a Hagar RCD (model number CN284U). This is a type AC RCD and I wish to replace it with a type A.

The model number for the Type A equivalent is CNA584U.

They are both 100mA, 100A, S type.

The only difference being is that the Type A RCD is referred to as 1P + N rather than double pole. I'm getting a bit confused by the difference?
I thought the +N meant that the N is just switched off when there is a fault but doesn't actually detect the fault itself.

What is the difference between a double pole RCD and a 1P + N RCD? With both types of RCD the phase and neutral become open if a fault is detected, so it must relate to where the fault is detected (i.e phase or neutral). Or.. it is just different terminology meaning the same thing?

Not really relevant with an RCCB. If it were an RCBO then it would lack overcurrent protection in the neutral pole, but an RCCB doesn't provide overcurrent protection anyway.

 

[HappyHippyDad]

Not really relevant with an RCCB. If it were an RCBO then it would lack overcurrent protection in the neutral pole, but an RCCB doesn't provide overcurrent protection anyway.

So it's just a difference in terminology and not in any actual characteristics of the device?

 

[brianmoooore]

I'd argue that DP RCD is incorrect. A 2 channel RCD compares the current in one channel with that in the other, and to be meaningful, that means comparing the live current with the neutral current.
A DP device is what I use with my split phase supplies that are common where I live. If I used a DP RCD to supply 460V equipment, that would work fine unless the equipment had a neutral connection as well, when the RCD would trip every time more current was drawn on one phase than the other. I would have to use a DP and N RCD, so, by extrapolation, a RCD for single phase supplies is 1P + N.

 

[pc1966]

I would have to use a DP and N RCD, so, by extrapolation, a RCD for single phase supplies is 1P + N.

Do you normally use a 4P RCD and just leave one pole unused?

 

[davesparks]

What is the difference between a double pole RCD and a 1P + N RCD?

Nothing, it's two different ways of describing the same thing. 1P+N I think would be technically correct, in the same way you'd describe a 3 phase one as 3P+N, and DP is just a commonly used term.

 

[brianmoooore]

Yes, 4P, taking note to use the poles that connect to the test switch.

 

[HappyHippyDad]

Nothing, it's two different ways of describing the same thing. 1P+N I think would be technically correct, in the same way you'd describe a 3 phase one as 3P+N, and DP is just a commonly used term.

Thanks, that's a good way of explaining it and makes it clear.

 

[Lucien Nunes]

I agree that for a plain RCD, the terms should be synonymous. With an RCBO I would expect to find a 1P+N device monitoring the current in the line pole only, just as with a 1PSN MCB. A DP device would monitor the current in both poles as required on systems where neither live conductor is a neutral, e.g. 55-0-55V CT-E supplies.

 

[timhoward]

I'm waking up an older thread. Silly question:
If I want a 1 module domestic Hager RCBO that switches the Neutral, does one actually exist as everything I can find at CEF and TLC has a diagram on the side showing an unswitched Neutral.

(and I don't want an AFDD!)

 

[Risteard]

I'm waking up an older thread. Silly question:
If I want a 1 module domestic Hager RCBO that switches the Neutral, does one actually exist as everything I can find at CEF and TLC has a diagram on the side showing an unswitched Neutral.

(and I don't want an AFDD!)

Not aware of a single module one.

 

[SparkySy]

Yes they are available (Hager) I have had a quote for one from CEF a couple of days ago £125.00 +Vat single module 2pole.
Sy

 

[nicebutdim]

Yes they are available (Hager) I have had a quote for one from CEF a couple of days ago £125.00 +Vat single module 2pole.
Sy

At that price, I'd be expecting free arc fault detection

 

[SparkySy]

So would I, I nearly fell over when the quote came back!

 

[Risteard]

Yes they are available (Hager) I have had a quote for one from CEF a couple of days ago £125.00 +Vat single module 2pole.
Sy

Do you have a product code for it?

 

[SparkySy]

Indeed I do as taken from the quote

ADA906U 6A 30mA 6KA Type RCBO £125.95 each

No CEF stock number unfortunately, not sure why but will ask them tomorrow when in there!

 

[Risteard]

Indeed I do as taken from the quote

ADA906U 6A 30mA 6KA Type RCBO £125.95 each

No CEF stock number unfortunately, not sure why but will ask them tomorrow when in there!

Cheers. I've brought up a picture of it from Hager and it appears to be 2 module?

In fact similar to the AD906J we get here (although it has no flylead).

RCBO 1P+N 6kA B-6A 30mA A • ADA906U | Hager UK

Find products, RCBO 1P+N 6kA B-6A 30mA A Class and more on Hager United Kingdom

hager.com

Technical Properties AD906J

Technical Properties

www.hager.ie

 

[SparkySy]

Well I will definitely be speaking to them in that case as I need it to be 1 module! Thanks @Risteard !

 

[mainline]

Got to love Hager £90 from them £15 from elsewhere

CEF List lots of Hager rcbos as being SP+N but are definitely not.

 

[SparkySy]

So an update, went in today and @Risteard was indeed correct, Hager do not seem to list a single pole switch neutral or double pole in a single module size even the AFDD RCBO are single pole.
So I will be changing the lot for Fusebox as they do make a single module double pole RCBO at a very reasonable price!

 

[LewisM]

So an update, went in today and @Risteard was indeed correct, Hager do not seem to list a single pole switch neutral or double pole in a single module size even the AFDD RCBO are single pole.
So I will be changing the lot for Fusebox as they do make a single module double pole RCBO at a very reasonable price!

Any questions like this message Hager on the whatsapp support number they are really helpful and normally reply within a few hours

+44 7778 161000

 

[timhoward]

Got to love Hager £90 from them £15 from elsewhere

CEF List lots of Hager rcbos as being SP+N but are definitely not.

Yes, this was my point of confusion. I was also wondering if they were using old photo's and the side diagrams were wrong.

So an update, went in today and @Risteard was indeed correct, Hager do not seem to list a single pole switch neutral or double pole in a single module size even the AFDD RCBO are single pole.
So I will be changing the lot for Fusebox as they do make a single module double pole RCBO at a very reasonable price!

It sounds as though you were in a similar position. The install I was thinking of has a perfectly good Hager metal enclosure but with a 30ma RCD main switch. It also has 14ma of earth leakage already and there is a lot of dodgy modifications. Changing to RCBOs already looked expensive, but if they are only single pole then yes, it's Fusebox all the way.
It seems strange that mid-range brands have RCBO's that switch the neutral but Hager doesn't seem to offer one that is a single module.

 

[DPG]

Yes, this was my point of confusion. I was also wondering if they were using old photo's and the side diagrams were wrong.

It sounds as though you were in a similar position. The install I was thinking of has a perfectly good Hager metal enclosure but with a 30ma RCD main switch. It also has 14ma of earth leakage already and there is a lot of dodgy modifications. Changing to RCBOs already looked expensive, but if they are only single pole then yes, it's Fusebox all the way.
It seems strange that mid-range brands have RCBO's that switch the neutral but Hager doesn't seem to offer one that is a single module.

The big companies sometimes lag behind smaller ones. Look at what happened to Kodak when digital printing came along.

 

[nicebutdim]

It seems strange that mid-range brands have RCBO's that switch the neutral but Hager doesn't seem to offer one that is a single module.

I've wondered about this, and similar issues, and the best I can come up with is that manufactuers concentrate their efforts on primary markets.

It may be that I'm wide of the mark here, but Crabtree, Wylex, Fusebox, SBS et all seem to primarily serve the UK market, whereas Hager, Schneider etc would primarily serve the continental European market and we get whatever suits from their respective ranges.

 

[brianmoooore]

Hager, Schneider etc would primarily serve the continental European market and we get whatever suits from their respective ranges.

But Europe has been using SP + N devices for years. I've bought SP + N MCBs in France and brought them back with me, years before such things were readily available in the UK.
If anything, I would expect the UK focused suppliers to be lagging behind.

 

[nicebutdim]

But Europe has been using SP + N devices for years. I've bought SP + N MCBs in France and brought them back with me, years before such things were readily available in the UK.
If anything, I would expect the UK focused suppliers to be lagging behind.

Single module?

 

[brianmoooore]

Single module?

MCBs, yes. Never looked at RCBOs.

 

[nicebutdim]

MCBs, yes. Never looked at RCBOs.

It's RCBOs that this thread references.

I'm not sure I'd consider either UK or Europe to be 'lagging behind' the other and consider this to be more a matter of practicality.

Manufacturers whose products are primarily aimed at UK market would struggle to sell 2 module breakers, whereas European market sees less limitations on space within domestic distribution boards.

 

[Rubes30]

Wylex and Crabtree miniature RCBO’s are all SP and switched neutral.

Can get them around £18.00 if you look online.