socket pole nightmare

[AS]

Sat down with screwfix to buy steelclad double sockets to fix to our kitchen stone walls as thought these looked quite nice and a bit industrial,etc - when help these sockets are single pole - what does that mean - call around no-one knows and anyone who does won't explain!

Can I take off old plastic on metal buried boxes and replace with these steelclad surface mounted SINGLE pole boxes or is this dangerous? esp in a kitchen?
We have storage heating and so have a two-phase supply. Why would these boxes only come in single pole if it is considered lower standard?

Any help would be great so I can order the things which I thought would take 5 mins and seems to be taking 2 weeks and extensive research!
Thanks

 

[Lectrician]

Single pole simply means only the live is switched off via the socket switch - not dangerous, and most cheaper sockets are only single pole.

You will struggle to fit these in place of flush sockets, as the cables will be too short, and you will have nowhere to fix to!!

 

[breezer]

single pole means the switch only turns one pole off (live) double pole means it will turn live and neutral off

 

[Lectrician]

Beat ya

 

[breezer]

only by a minute

 

[andy]

so have a two-phase supply

???

 

[ryanj]

Around this area, a lot of houses used to have a two-phase supply, when storage heaters were the fashion. The DNO seem to have converted them all back to single phase, with the extra conductor being the earth. (Overhead TT, now TN-S)

 

[Lectrician]

Storage heaters are used alot in the sticks, and very often had a 'two phase' supply.

In the sticks where they only distribute two of the 11,000volt phases, only 1 LV phase or a 'split' phase can be produced, a split phase very often gets confused for 2 phases, as it has 1 neutral, and two 'phases'.

Measure the volts between the 'phases' on a split phase supply, and you get 460-480 volt!!

 

[AS]

Thanks for the above -
most of my cables are hanging down the stone wall from upstairs at the moment (building site!!) so there is quite a lot of cable. I suppose this would normally run down some kind of piping to disguise the cable before it hits the metalclad surface mounted box. Can this piping be metal with the plastic cable inside?

Are these metal surface boxes earthed in the same way as the metal/plastic front type?

Do you know of any double pole metal clad boxes and is it common for these boxes to be used in domestic situations?

I assume the 2 phase supply issue wasn't relevant.

If you have single pole what is happening in the socket when the neutral isn't switched off? Does it mean there is still elec sitting in there waiting for the live contact and if you have d/p where live and neutral are off is there no elec sitting in the plug????????????

lets say s/p and d/p options are both switched off is one safer than the other in terms of a childs fingers being poked in?

Do building regs require d/p?

 

[ban-all-sheds]

I'm hopelessly confused - the metalclad sockets that Screwfix sell are MK, and all MK's ones are DP: http://www.mkelectric.co.uk/PDF/range/Metalclad Plus.pdf

As for the cables not being long enough, you could complete the industrial look by using surface mounted metal conduit.

 

[plugwash]

BAS look further down the list on http://www.screwfix.com/app/sfd/cat/cat.jsp?cId=101965&ts=24327 and you will see unbranded ones

usuall when two phase is said it really refers to either split phase or two phases from three phase. True two phase is sine and cosine wave power.

http://en.wikipedia.org/wiki/Two_phase
http://en.wikipedia.org/wiki/Split_phase
http://en.wikipedia.org/wiki/Three_phase

 

[ban-all-sheds]

BAS look further down the list on http://www.screwfix.com/app/sfd/cat/cat.jsp?cId=101965&ts=24327 and you will see unbranded ones

Sorry - didn't scroll down that far. And anyway - it doesn't explicitly say that they are SP - just doesn't say DP.

But if this is the case, maybe confirmed by Screwfix, then:

AS: You are a bl**dy idiot.

If you're concerned that the sockets you've chosen are SP and not DP, then bl**dy well un-choose them, and pick ones from the same supplier, on the same page, which are DP, thus addressing your concern!

 

[ban-all-sheds]

Thanks for the above -
most of my cables are hanging down the stone wall from upstairs at the moment (building site!!) so there is quite a lot of cable. I suppose this would normally run down some kind of piping to disguise the cable before it hits the metalclad surface mounted box. Can this piping be metal with the plastic cable inside?

It can indeed. Unless you have just straight runs everywhere you'd be better off with singles than T/E, as that's a b*gger to pull through conduit bends.

Are these metal surface boxes earthed in the same way as the metal/plastic front type?

In theory if the conduit is all properly assembled it can be earthed at one point, but it'd be more sensible not to rely on that, and earth normally at each socket and switch.

Do you know of any double pole metal clad boxes and is it common for these boxes to be used in domestic situations?

MK, and they look just the same as those Screwfix knock-offs, so if you're happy with one you'll be happy with the other.

I assume the 2 phase supply issue wasn't relevant.

Irrelevant to the SP/DP issue. Not irrelevant if you have 2 phases in the same room, as IIRC you have to have warning labels about this.

If you have single pole what is happening in the socket when the neutral isn't switched off? Does it mean there is still elec sitting in there waiting for the live contact and if you have d/p where live and neutral are off is there no elec sitting in the plug????????????

Electricity doesn't sit anywhere. Are you sure you understand enough basic stuff to be doing wiring?

lets say s/p and d/p options are both switched off is one safer than the other in terms of a childs fingers being poked in?

It shouldn't be possible to poke fingers in - BS1363 requires the sockets to be shuttered...

(Nor, IMHO, should children ever be left alone or unsupervised in a kitchen...)

But even so, it's very unlikely to be dangerous, unless you've reversed the polarity, or you've got a TN-C-S supply with a broken neutral somewhere in the supply network.

Do building regs require d/p?

No.

 

[AS]

Thanks B-A-S

i wasn't specifically Choosing the single pole sockets - I just wanted to know why the two pole types were offered and if one was better than the other or if they were relevant to specific situations. At £10.00 a head more expensive per socket for the MK d/p ones - I thought perhaps they were some special thing and that the single pole ones were more the normal thing. So all I wanted to do was understand the difference and why anyone would use single pole or double pole and why there was even a choice.

It seems clear from your reaction that D/P is the better to use and that single pole must just be a cheapo equivilant and not the norm to choose.

All the wiring we have is existing wiring - all I am doing is changing the sockets and repositioning some of them for practical reasons. i didn't want to buy the wrong socket type.

By the way can you tell from looking at the back of an exisitng socket whether it is a single pole socket or a double pole.

 

[ban-all-sheds]

Thanks B-A-S

i wasn't specifically Choosing the single pole sockets

Sorry - misinterpreted.

- I just wanted to know why the two pole types were offered and if one was better than the other or if they were relevant to specific situations. At £10.00 a head more expensive per socket for the MK d/p ones - I thought perhaps they were some special thing and that the single pole ones were more the normal thing. So all I wanted to do was understand the difference and why anyone would use single pole or double pole and why there was even a choice.

They aren't £10 more - the MK doubles are £10.99 and the other ones are £4.45.

There's a choice because not everybody wants to pay more for DP versions, although with MK part of the extra is not just for DP switching, it also buys you a better made product. MK may have lost the plot with their CUs, but their accessories are still first class. As with anything though, there are different price/quality points targetted at different markets.

Also, the MK ones look better:

It seems clear from your reaction that D/P is the better to use and that single pole must just be a cheapo equivilant and not the norm to choose.

I think DP is better, and I'd never choose SP, but there's no rational reason really - we're all happy with SP light switches and SP MCBs...

Single Pole sockets just seem C&N, that's all...

All the wiring we have is existing wiring - all I am doing is changing the sockets and repositioning some of them for practical reasons. i didn't want to buy the wrong socket type.

If you aren't replacing the cables, check before you buy any sockets that you've got enough slack in the cables to be able to use surface mount accessories - you probably don't...

By the way can you tell from looking at the back of an exisitng socket whether it is a single pole socket or a double pole.

Not unless it has that info moulded into the plastic.....