SP or DP sockets - Whats the difference?

Probably something really simple but............

Replacing all the boxes, some of which are bakelite, and the faces with new MK range ones. Some of the existing sockets, singles and doubles, are spurs all of which run off the main ring.

I have checked the amount and they do not exceed the current regulations. Does the "DP" mean the faces are for sockets on the main ring and "SP" for the spurs. I wanna get the right ones for the right places obviously - but MK do not do "SP'" faces.

Toptec

DP = double pole = makes/breaks both phase and neutral.
SP = single pole = makes/breaks phase only.

There is no requirement to use double pole sockets but they don't cost much more and because they break both P+N they can isolate an appliance totally without the need for the plug to be removed.

SP - Single Pole. Switch isolates just the live conductor.

DP - Double Pole. Switch isolates both the live and neutral conductor.

Use Double Pole (DP) sockets.

Thanks Guys - Fully understood.

This forum is 1st Class.

Toptec

To be pedantic a single pole is safer than a double pole because you could have a fauty switch and only break the neutral so it would still be live always best to pull the plug.

lookinn said:

To be pedantic a single pole is safer than a double pole because you could have a fauty switch and only break the neutral so it would still be live always best to pull the plug.

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You could have a faulty SP switch which would leave both poles connected. So?

Crafty said:

lookinn said:

To be pedantic a single pole is safer than a double pole because you could have a fauty switch and only break the neutral so it would still be live always best to pull the plug.

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You could have a faulty SP switch which would leave both poles connected. So?

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With a defective DP that breaks only the neutral the equipment will stop and appear to be switched off when in fact all the mains wiring is still connected to live via the defective non opening switch.

But what fool would open up an appliance that is still plugged in anyway??

Crafty said:

But what fool would open up an appliance that is still plugged in anyway??

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Might be a hard wired isolation switch?

tim west said:

Crafty said:

But what fool would open up an appliance that is still plugged in anyway??

Click to expand...

Might be a hard wired isolation switch?

Click to expand...

Safe isolation? Always check for voltage.
If you're not competent then you shouldn't be putting your fingers in silly places.

tim west said:

Crafty said:

But what fool would open up an appliance that is still plugged in anyway??

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Might be a hard wired isolation switch?

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I once had that on an RCD fault I was tracing.

Unplugged all the appliances and turned of all the DP FCUs on the circuit, but the FCU supplying the faulty equipment had a welded neutral so the fault was still showing even with the FCU turned off.

Nightmare it was.

GaryMo said:

tim west said:

Crafty said:

But what fool would open up an appliance that is still plugged in anyway??

Click to expand...

Might be a hard wired isolation switch?

Click to expand...

Safe isolation? Always check for voltage.
If you're not competent then you shouldn't be putting your fingers in silly places.

Click to expand...

Well said! But Crafty was mentioning opening which you would do next after isolating, this is where you would probably then find you have a faulty Isolation Switch by measuring the supply terminals to the appliance

personally i would not advise trusting a plateswitch, socket switch or fcu switch as a means of safetyisolation even if it is double pole. There is no positive indication of contact position and the switches are very easy to swtich by accident.

and remember where possible work like it's live even if it's dead!

Sorry to dig this one up from the past, but I was just double poling the answer to this prior to doing the 6 double gangs in the kitchen - you think that's enough for a kitchen?

There are some good replies.

The best is last, perhaps the one I most agree with in terms of safety. I now never trust the breakers or the sockets to be truly off, the are a couple of sockets lurking around, for example, that are still 100% live when the break for that room is off, since the house is so old and so many different people have added, removed or modified the rings.

But specifically, I like the point about the switches being easy to flick back on.

At one point, I was adding a new plug to an extension cable for a female cat. Mid doing it, and with me stripping the wires with my teeth, she plugged the other end back in.

I stopped, fairly stunned, and said "I have this in my mouth...."

"Yeah, but it's not switched on"



There is a small possibility (quite a large one) she was intending to frazzle me for fun. However, an equally large chance is the womans ability to confuse the ordering of events. E.g. Why plug it in now and not when it's done? What difference does it make to the time or effort involved? If that's their version of multitasking, it's horrifically bad.

Yes, I know, teeth stripping is bad. I never do it on solid cores, anything that's permanently wired and always have the sockets off, the cable unplugged and the other end in sight, or beside me.

And I've since bought one of those natty strippers that actually works, the snap pliers kind.

But damn......

I have also developed a habit of never touching the bare connectors even if I assume it's dead. I'll spread the wires as far apart as possible, then only touch the insulation a good way back, the plastic of the plates and do the wiring with a VDE screwdriver. I also duct tape the bare connectors if I'm leaving the room.

This forum is another example. On most, if I click reply, it'll autoquote the last reply to show me it's replying. But here, I can click new topic or reply and the pages look identical at a glance.

johnheritage said:

Sorry to dig this one up from the past, but I was just double poling the answer to this prior to doing the 6 double gangs in the kitchen - you think that's enough for a kitchen?

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Yes


No


Maybe


In any event, if it doesn't have 6 now, then adding more is notifiable.

At one point, I was adding a new plug to an extension cable for a female cat.

Click to expand...

You have a cat with its own extension lead?

Mid doing it, and with me stripping the wires with my teeth, she plugged the other end back in.

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And it can manipulate plugs?

"Yeah, but it's not switched on"

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And speak?

There is a small possibility (quite a large one) she was intending to frazzle me for fun.

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Would serve you right, and do us all good - the gene pool is better off without people who are so f****** incompetent and stupid that they'd strip wire with their teeth.

I have also developed a habit of never touching the bare connectors even if I assume it's dead.

Click to expand...

You shouldn't need to assume. Safe working practices mean that you know.

This forum is another example. On most, if I click reply, it'll autoquote the last reply to show me it's replying. But here, I can click new topic or reply and the pages look identical at a glance.

Click to expand...

No they don't.

gets you a posting window populated with the post you are quoting.

gets you a page with "Post a reply" in bold at the top, and a scrollable history of the most recent posts at the bottom.

gets you a page with "Post a new topic" in bold at the top and (obviously) no scrollable history of the most recent posts at the bottom.

Maybe you should try to stop doing things at a glance if a glance is not sufficient for you to work out what's going on.