Difference between "Single pole with switched neutral" AND "Double Pole" ?

[binky]

welders, transformers, high bay lights and 110V site supply

Sounds very old school to me, but I do very little industrial stuff.

 

[nicebutdim]

Never seen a 2 phase supply over here.

 

[poni]

Never seen a 2 phase supply over here.

you have never used a 110V centre taped transformer for site tools?

 

[nicebutdim]

you have never used a 110V centre taped transformer for site tools?

I mean two phase supply to a premises.

 

[mainline]

you have never used a 110V centre taped transformer for site tools?

That isn't 2 phases, it's two halves of the same 110V single-phase.

 

[poni]

That isn't 2 phases, it's two halves of the same 110V single-phase.

caught me, yes its not two phase, but it is a double pole supply,

 

[poni]

I mean two phase supply to a premises.

nether have I ,normally 3 phase then split up at the DB (into 3 phase circuits, 2 phase circuits and single phase,)

 

[SPECIAL LOCATION]

I was hesitant about making bold statements in my previous reply for this very reason. Do they state that both poles must be switched or specifically that a 'double pole' device must be used. The latter isn't particularly common in the UK for RCBOs in a domestic board and would be two modules wide - at least I'm yet to learn of any single module, double pole RCBO. It's not ideal to fit an additional 2 way board for every EV charge point, but that would be the easiest way of providing true double pole isolation - RCD and MCB.

Makes me wonder if the IET need to be more specific or if they've been adequately specific in this matter.

erm... there are various single module, Live & Neutral switched, (what I understood as "Double pole"), RCBO's available in the UK..
e.g. Crabtree Starbreaker RCBO's switch the neutral as well!

https://www.tlc-direct.co.uk/Products/CB61slashBM3230.html
"Starbreaker Miniature RCBOs with switched neutral built in as standard will fully isolate a faulty or damaged circuit by disconnecting live and neutral conductors."

And MK Sentry:-
https://www.cef.co.uk/catalogue/pro...1-module-b-curve-6ka-30ma-type-a-compact-rcbo
"The MK Sentry range features neutral switched type double pole RCBOs in one module format."

etc.. etc.. google should offer other options..?

 

[nicebutdim]

erm... there are various single module, Live & Neutral switched, (what I understood as "Double pole"), RCBO's available in the UK..
e.g. Crabtree Starbreaker RCBO's switch the neutral as well!

https://www.tlc-direct.co.uk/Products/CB61slashBM3230.html
"Starbreaker Miniature RCBOs with switched neutral built in as standard will fully isolate a faulty or damaged circuit by disconnecting live and neutral conductors."

And MK Sentry:-
https://www.cef.co.uk/catalogue/pro...1-module-b-curve-6ka-30ma-type-a-compact-rcbo
"The MK Sentry range features neutral switched type double pole RCBOs in one module format."

etc.. etc.. google should offer other options..?

Those single module RCBOs do switch both poles, but are distinctly different from double pole devices. This thread was started to discuss that very issue and early posts highlight the difference.

 

[SPECIAL LOCATION]

Those single module RCBOs do switch both poles, but are distinctly different from double pole devices. This thread was started to discuss that very issue and early posts highlight the difference.

Possibly you need to inform MK...? as their data sheet describes the single module RCBO I linked previously as "Double Pole"?

https://mksentrycircuitprotection.c...s/2024/12/Mini-RCBOs_Circpro_Technical_v7.pdf

e.g. Features • Single module • Meet BS EN and IEE Wiring Regulation requirements • Allows both overcurrent and earth fault protection and detection • Available in a range of current ratings • Tunnel type terminals • Generous terminal capacity • Positive contact status indication • Double Pole • Bi-directional

 

[nicebutdim]

Possibly you need to inform MK...? as their data sheet describes the single module RCBO I linked previously as "Double Pole"?

https://mksentrycircuitprotection.c...s/2024/12/Mini-RCBOs_Circpro_Technical_v7.pdf

e.g. Features • Single module • Meet BS EN and IEE Wiring Regulation requirements • Allows both overcurrent and earth fault protection and detection • Available in a range of current ratings • Tunnel type terminals • Generous terminal capacity • Positive contact status indication • Double Pole • Bi-directional

I don't believe they described them in that way before MK circuit protection was discontinued by Honeywell and licensed to another company. Maybe they're right and maybe they aren't, but I'd be surprised if they've managed to produce a true double pole RCBO into one module, without fanfare, when no other manufacturer has managed to do so.

Other manufacturers have, in the past, used 'double pole' to describe SP+N RCBOs, but subsequently corrected that term. I haven't looked to see what they IET say on this matter, but strongly suspect the SP+N moniker didn't come about without good reason.

 

[mainline]

Possibly you need to inform MK...? as their data sheet describes the single module RCBO I linked previously as "Double Pole"?

https://mksentrycircuitprotection.c...s/2024/12/Mini-RCBOs_Circpro_Technical_v7.pdf

e.g. Features • Single module • Meet BS EN and IEE Wiring Regulation requirements • Allows both overcurrent and earth fault protection and detection • Available in a range of current ratings • Tunnel type terminals • Generous terminal capacity • Positive contact status indication • Double Pole • Bi-directional

Double pole disconnects both the live and neutral wires for full isolation.

Sp+N Is not considered to be a true double pole device, as it doesn't control two separate circuits simultaneously.

 

[Fleeting]

The requirement for EVSEs is that the protective device disconnects all live conductors how this happens is not relevant.

 

[nicebutdim]

The requirement for EVSEs is that the protective device disconnects all live conductors how this happens is not relevant.

I'd raised the issue of wording previously and had since forgotten to check. You're correct in stating the above and SP+N RCBOs meet regulatory requirements.

 

[Fusewirey]

Double pole disconnects both the live and neutral wires for full isolation.

Sp+N Is not considered to be a true double pole device, as it doesn't control two separate circuits simultaneously.

Please clarify:

What event is an example where a 'double pole' device and a 'SP+N' device would act differently?

 

[mainline]

Please clarify:

What event is an example where a 'double pole' device and a 'SP+N' device would act differently?

Reverse polarity could be one.

The lack of overcurrent protection on the N.

The N contacts are more like a simple switch, rather than having the same breaking capacity as the L side.

As already said, in most scenarios it won't make much difference.

 

[Fusewirey]

Is some of this the result of manufacturers going from two module width to one module width, and choosing to down-grade the spec as a result?

And in the other dimension, were consumer units that could only fit 45mm high devices the most popular, and could not handle 72mm ones?

 

[nicebutdim]

I've always assumed the drive toward compact form is mostly due to the space restraints often encountered in domestic properties. Even since the advent of electricity, builders don't seem inclined to provide an inch more than necessary for its distribution. Even larger, modern properties have plant rooms primarily designed for other services and we're generally just lucky enough to have a bit of unused wall space to work with.

Fairly certain at least a few continental European countries require the sort of double pole protection that gives rise to our SP+N distinction, which is why they're well use to two module wide devices in boards considerably larger than the UK allows for.

Edit: I do like the more compact form we use in domestic properties, but it would be nice having twice the space to work with. I spend my days working in spacious boards, then evenings in the tighter confines of under stairs or a downstairs toilet asking myself it the money is worth it.

 

[Marvo]

I was told that a 2 pole RCBO has both sets of contacts sized to break full rated max current while SP+N has overcurrent sensing only in phase side and smaller/slower contacts for N which are timed to open after the phase contact has done the big switching event - don't know how true that was?

Agree with Running Piglet. I'm not sure if things have changed but it used to be that an SP+N breaker will break last and make first the neutral and has no overload protection on the neutral pole. A 2-pole breaker obviously both poles feature mag and thermal overload and no particular order to the making and breaking of the poles. I only know for a fact in the old Heinemann MCB's the SP+N version had equally sized contacts on both poles but it wouldn't surprise me if modern versions had a smaller neutral contact in the interest of saving a tenth of a gram of brass.

 

[binky]

Edit: I do like the more compact form we use in domestic properties, but it would be nice having twice the space to work with. I spend my days working in spacious boards, then evenings in the tighter confines of under stairs or a downstairs toilet asking myself it the money is worth it.

I've spent so much time in understairs cupboards, Harry Potter would be jealous