Does a new cooker extractor need a plug socket if it has a plug?

[ydrol]

> Previous owner put in metal mains Sockets in the kitchen

I probably shouldn't have mentioned this aside. .. I confused everyone. The plastic screws are in the plastic light switches on the unearthed lighting circuit only.
The Kitchen mains sockets is separate and newer.
I only mentioned the screw thing to indicate my electrician was fairly diligent in some areas. (but not in others - but that's another story!)

 

[ydrol]

I don't want to be the pedant, but a double pole isolator is needed somewhere, but only at the origin, i.e. the main isolator. All others don't need, although usually instructions for things request double pole isolators anyway, presumably local to the appliance.

Also BS requires polarity to be correct (basically for that reason), but if it's not for some reason, then a double pole isolator is the next best thing.

Would it helped if I took a picture behind the isolator switch ?
Had a new metal fuse box + RCD put in last year too BTW.

 

[JohnW2]

Previous owner put in metal mains Sockets in the kitchen

Indeed, but the plastic screws were in plastic switches on the lighting circuit without a CPC. The metal sockets were presumably on a circuit with a CP, and hence properly earthed.

Kind Regards, John

 

[JohnW2]

I don't want to be the pedant, but a double pole isolator is needed somewhere, but only at the origin, i.e. the main isolator.

Not 'somewhere', but specifically at the origin of an installation (if it is in the control of 'ordinary perons'!). However, we were not talking about that and, as you say, in any other situation/location, the regs do not require DP isolation in TN installations.

Also BS requires polarity to be correct (basically for that reason), but if it's not for some reason, then a double pole isolator is the next best thing.

Indeed, that's why (and probably the only reason why) I said that DP isolation always "seems to make sense" (even if the regs don't usually require it), even in a TN installation.

Kind Regards, John

 

[stillp]

Isolation is defined in the IEC standards as including disconnection of all live conductors. BS7671 only refers to "all sources of electrical energy", but it could be argued that includes the neutral.

 

[JohnW2]

Isolation is defined in the IEC standards as including disconnection of all live conductors. BS7671 only refers to "all sources of electrical energy", but it could be argued that includes the neutral.

BS7671 is a lot more explicit than you suggest ...

.... In a TN-S or TN-C-S system, it is not necessary to isolate or switch the neutral conductor where it is regarded as being reliably connected to Earth by a suitably low impedance."

Kind Regards, John

 

[Risteard]

BS7671 does not actually require isolation to be double-pole in TN installations.

Actually it does for domestic installations, as they cannot be considered to be under the control of whatever the new term is for skilled and instructed persons.

However, you will find that local isolators are unlikely to be required for the majority of situations where they are fitted.

 

[JohnW2]

Actually it does for domestic installations, as they cannot be considered to be under the control of whatever the new term is for skilled and instructed persons.

As I wrote above, only at the origin of the installation (537.1.4). For isolators anywhere else, the generic 537.2.1.1 (which states that neutral doesn't need to be isolated in TN installations) appears to apply, regardless of whose 'control' the installation is under.

Interestingly, 537.1.4 refers specifically to single-phase installations under the control of 'ordinary persons'. That presumably means that, although I count as an 'ordinary person', were my (3-phase) supply a TN one (which it isn't), there would not be a requirement for all-pole isolation at the origin!

Kind Regards, John

 

[ban-all-sheds]

Meanwhile, in a topic on the other side of town...

ydrol - do you know what route the cable(s) take between these two points?

Also, that's flex coming out of the wall, so unless there's flex leaving the switch you've got a junction box hidden away somewhere.....

 

[ydrol]

I've no idea but the tiles are being changed and the handyman suspects the plaster will come off with them I'll see if I can get a pic via phone or action cam (and try not to drop it!).

 

[ban-all-sheds]

the handyman suspects the plaster will come off with them.

If there is any, and they aren't glued directly to the board.

 

[Mikefromlondon]

It is an old installation, what you are doing is replacing your old hood with a new kitchen hood, with minimum fuss, you are not rewiring your house, so just connect your new hood to existing terminal strip, and wrap insulation tape over it, tuck it back, and you already have a fused isolator switch, just make sure the fuse is not 13amp, as fan doesn't need much more than 3amps, so why do you want to prolong your task, or pull your tiles away and try and fit a back box, you never had one for so many years why now? would be different if you were rewiring all your house and so new and latest standards would apply, it is not like H&S is going to dream that you haven't used a back box and would come to inspect your new fan and order you to put it right to latest regs. It won't make your installation any unsafe if you didn't use a back box, long as your terminal strip is well rated for the current and all wires inserted without any strands or insulation pulled back, screws should be tight so no lose wires that can cause heating. If it was my house I would do it with minimum fuss.
The likely route for the cable would be straight up and then turn left towards hood, that is how most buried wires are done, not diagonally, but strange things do happen and many self proclaimed electricians do not follow standards. Original installation was most probably done by a self proclaimed electrician. In other words done by a kitchen fitters.

 

[ydrol]

Thanks - I agree on just cutting off the plug and putting the new one in place. I just wanted to double check because the handyman said I might need a plug socket. On balance of what's been posted here, I'm happy to just cut off the new plug and join it on to the existing connector. I'm assuming having a terminal strip ( plastic connector with little screws) is fine. with plenty of insulation tape on it like you said.

Regarding the rest of the kitchen , I'm not just doing the extractor fan, I'm getting a fair bit of other work done to *hopefully* attract a good tenant towards top end of what market will bear in this area (new worktops - mitered join, new sink , hob, oven, under counter fridge & freezer and yes changing the tiles - the bottom row will likely get damaged anyway when the old worktops come off, and the cupboard under the sink is partly water damaged)

 

[DetlefSchmitz]

and wrap insulation tape over it

Please don't! Use a decent enclosing box.

 

[ydrol]

Like this right ?