Couple of wiring questions

[Mfuller]

Hi There,

I have a couple of questions regarding my kitchen that I'm about to install. I wonder if a sparky could comment ? pretty please I really can't afford a sparky to do the work, but want to get it certified after I've done it all.

First off, I am replacing 5x 240v Halogens with 6x 50w LV's halogens. I was thinking of having 3 transformers wired parallel, e.g each transformer getting it's feed from a switched junction box. Is this the best way ? I already have 4 LV halogens on this 6a mcb circuit, and I assume adding another 6 is not a problem ?

My downstairs ring main is run from a 32a RCBO.

My Hob is gas, e.g the only electricity it uses, is for the spark to light the gas. Does this really need a separate feed or will a standard ring main socket do ? Does it have to have an isolation switch above the counter ? Same question for the hood ?

The oven (not sure of wattage as I haven't bought it yet) will have a separate feed to an isolation switch. The problem is, this isolation switch has to be visible, correct ? This will put it within arms reach of the sink.. not good. There is a wall on the other side of the cooker, so it can't go there. The unit the cooker is housed in is a tall cabinet. Anyone think of a way round it ?

The wires will be run in wall channels from upstairs. I was planning on running the cables through plastic conduit, then plastering over them.. is this acceptable under the regs or does it need to be metal conduit ?

I was going to run earth bonding to the main water inlet. It's about 5 meters from the CU to the water stop. What size earth cable should I use ? 6mm or 10mm ?

The sink is ceramic so no bonding needed there, the taps are metal but will have plastic piping.. I assume I don't need to earth them ?

Any other things I should consider to keep this installation up to the regs ?

Really appreciate any advise given. Thanks !

 

[Spark123]

I am replacing 5x 240v Halogens with 6x 50w LV's halogens. I was thinking of having 3 transformers wired parallel, e.g each transformer getting it's feed from a switched junction box. Is this the best way?

Not a problem

I already have 4 LV halogens on this 6a mcb circuit, and I assume adding another 6 is not a problem ?

If this is all that is on the lighting circuit, I don't see it is a problem.

My downstairs ring main is run from a 32a RCBO.
My Hob is gas, e.g the only electricity it uses, is for the spark to light the gas. Does this really need a separate feed or will a standard ring main socket do?

A feed from the ring main (I prefer VIA a Switched Fused Spur Unit) is OK

Does it have to have an isolation switch above the counter ? Same question for the hood ?

Yes, reading between the lines you need to be able to switch off for maintenance purposes (and in an emergency).

The oven (not sure of wattage as I haven't bought it yet) will have a separate feed to an isolation switch. The problem is, this isolation switch has to be visible, correct ? This will put it within arms reach of the sink.. not good. There is a wall on the other side of the cooker, so it can't go there. The unit the cooker is housed in is a tall cabinet. Anyone think of a way round it ?

Put the switch on the wall on the other side of the cooker?

The wires will be run in wall channels from upstairs. I was planning on running the cables through plastic conduit, then plastering over them.. is this acceptable under the regs or does it need to be metal conduit?

You do not really need to run the cables in conduit. You will be OK running it under capping (metal or plastic) which is only there to stop you damaging the cable when plastering up.

I was going to run earth bonding to the main water inlet. It's about 5 meters from the CU to the water stop. What size earth cable should I use ? 6mm or 10mm ?

You need to contact your regional electricity supplier for this advice as the sizing may change between geographichal location.

The sink is ceramic so no bonding needed there, the taps are metal but will have plastic piping.. I assume I don't need to earth them ?

You do not need to supplementary bond a kitchen sink.

 

[ban-all-sheds]

Does it have to have an isolation switch above the counter ? Same question for the hood ?

Yes, reading between the lines you need to be able to switch off for maintenance purposes (and in an emergency).

The switched FCU will also give you isolation.

The oven (not sure of wattage as I haven't bought it yet) will have a separate feed to an isolation switch. The problem is, this isolation switch has to be visible, correct ? This will put it within arms reach of the sink.. not good. There is a wall on the other side of the cooker, so it can't go there. The unit the cooker is housed in is a tall cabinet. Anyone think of a way round it ?

Pullswitch on the ceiling?

The wires will be run in wall channels from upstairs. I was planning on running the cables through plastic conduit, then plastering over them.. is this acceptable under the regs or does it need to be metal conduit?

It's always a Good Idea to use conduit - makes later modifications much easier.

Also, see these to make sure you're putting cables in the right places:

http://www.niceic.org.uk/downloads/C5-43.pdf

http://www.niceic.org.uk/downloads/concealedcables.pdf

I really can't afford a sparky to do the work, but want to get it certified after I've done it all.

What do you mean by certified? - What sort of certificate are you hoping to get?

Any other things I should consider to keep this installation up to the regs ?

Buy these and familiarise yourself with the relevant regs...



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[Mfuller]

OK excellent, thank you all for the great advice ! I wasn't far off the mark then

 

[Mfuller]

OK, here's a quick question that I am confused about. In this document..

http://www.niceic.org.uk/downloads/C5-43.pdf

It seems to suggest that wiring down the wall *does* need some kind of metal earthing sheild, be that a metal covering (armoured cable) or metal conduit so that if a nail penetrates the cable, it will first go through an earthed metal conductor.

Am I mis-reading this ?

Thanks

Marc

 

[ban-all-sheds]

I think you might be. Basically cables must be buried 50mm or more deep, or have mechanical protection (integral to their construction or external) or:

(iv) be installed in a zone:
(a) within 150 mm from the top of the wall or partition, or
(b) within 150 mm of an angle formed by two adjoining walls or partitions, or
(c) either horizontally or vertically, to the point, accessory or switchgear on the surface of the wall or partition, to which the cable is connected or passes through.

So it's only cables running down walls where there is no accessory to alert you to their presence that need to be deep or protected. Except, IMO, in kitchens, where you have cables running vertically down from the ceiling to sockets hidden below worktops. These should not be regarded as being in a zone where they need neither protection or to be buried more than 50mm deep, but that's my personal interpretation of the spirit of the regulations, not what they actually say. I think it makes sense - the idea is that if you see an accessory on the wall you should be alerted to the presence of a buried cable, but if you (or a future occupant) can't see the accessory.....

 

[Mfuller]

(c) either horizontally or vertically, to the point, accessory or switchgear on the surface of the wall or partition, to which the cable is connected or passes through.

I think it makes sense - the idea is that if you see an accessory on the wall you should be alerted to the presence of a buried cable, but if you (or a future occupant) can't see the accessory.....

Ah yes, that makes sence. Part (c) will apply to my situation. I will have one socket behind a cabinet that will not be easily seen however, but I would hope the cooker isolation switch will alert anyone that a cable is buried in there.

Damn confusing these regs

Thanks mate

Cheers

Marc

 

[ban-all-sheds]

Far from restricting DIY electrical work, I think that there is a case to be made for mandating that people rewire their own houses when they move in - that way they'll know where all the cables are.

Zones or no zones, accessories or no accessories, I'd never drill into a wall unless I knew that there were no cables there. Even if the wall was completely bare, I'd turn off the power, and after re-energising I'd check for voltage on the screws...

 

[Qedelec]

I'm with you on that.
I heard that there are discusions as to whether cables in partition walls should incorporate an earthed foil sheath as there was a case recently where a screw had penetrated the phase making the metal framework live. It was only discovered when a ventilation engineer was killed by attaching his ducting to the frame.