1 OR 1.5mm twin & earth cable for bathroom LED downlighters... discuss

scousespark · 25 Sep 2017

JohnW2 said:
That's obviously the correct process (whether or not the installer is a qualified electrician). So why ....

I'm a bit confused - are you saying that the "lot of us" you referred to above does not include yourself?

Kind Regards, John

You have a real issue with me. Every time I post, you take it upon yourself to show me where I'm going wrong. Two question marks, seriously?
How simple do you want it? Some of us (as in people installing lighting circuits) will install 1.5mm2 cable as this is always suitable, where 1.0mm2 is not always so. I'm not in that camp, but neither practice is right or wrong.

Is that clear enough?

ban-all-sheds · 25 Sep 2017

jg321 said:
I fully agree with you here, however... What type of light fitting would be more appropriate, and not look rubbish in a modern bathroom? This is a genuine question, not least because I'm about to get a new bathroom fitted in my house, after spending many years living in "trendy" city centre flats with annoying downlighters in the bathroom. Annoying downlighters everywhere in fact.

I'm sure you must be able to find something else you like?

http://www.google.co.uk/search?q=bathroom+light&source=lnms&tbm=isch

Don't look in department stores or DIY sheds - their buyers seem to delight in only offering hideous clunky tat as alternatives to recessed ceiling torches. Try specialist lighting shops.

JohnW2 · 25 Sep 2017

scousespark said:
You have a real issue with me. Every time I post, you take it upon yourself to show me where I'm going wrong. Two question marks, seriously?

That really is incredibly rich, coming from you. I'm merely taking your lead. Do you not realise how substantial a proportion of your posts, on your occasional visits to the forum, consist of finding something I've written since your last visit you can 'take me to task' about? - and it is relatively unusual for you to do that to anyone else.

In any event, I don't think it's fair to say that I "show you where you have gone wrong" - and don't forget that is is very commonly you who starts an exchange between us, so it's not really fair to suggest that I look for things to 'pick up on' (there is someone in this forum who is far, far, more accomplished at that!). On this occasion, I was genuinely confused, since you appeared to be making rather contradictory statements (and I was not the only person who commented on that).

Kind Regards, John

rob4beer · 27 Sep 2017

Well I think its fair to say this has been discussed... haha

So i will use 1mm and look to buy different lights

1.5mm for sockets though yes?

JohnW2 · 27 Sep 2017

rob4beer said:
So i will use 1mm and look to buy different lights 1.5mm for sockets though yes?

Do you mean sockets on a 'sockets circuit'? If so, with very few exceptions, the minimum cable size would be 2.5mm².

Kind Regards, John

rob4beer · 27 Sep 2017

JohnW2 said:
Do you mean sockets on a 'sockets circuit'? If so, with very few exceptions, the minimum cable size would be 2.5mm².

Kind Regards, John

john, I was thinking of extending/adding to an existing socket (wire out the back leading to another socket) which I read is ok, but not as good as adding one to the main circuit? may be well out of date that one and horrendous practise lol

otherwise, identify the main socket circuit, chuck in a junction box and some fresh wires to the new socket?

ban-all-sheds · 27 Sep 2017

rob4beer said:
john, I was thinking of extending/adding to an existing socket (wire out the back leading to another socket) which I read is ok, but not as good as adding one to the main circuit?

Yes, it is, and no it isn't quite.

But why not use 2.5mm²?

otherwise, identify the main socket circuit, chuck in a junction box and some fresh wires to the new socket?

Why a junction box? What sort? Where would it go?

rob4beer · 27 Sep 2017

ban-all-sheds said:
Yes, it is, and no it isn't quite.

But why not use 2.5mm²?

I would use 2.5mm based on the advice given above for a socket...

Why a junction box? What sort? Where would it go?

I was thinking of creating a spur? i read that on google

so a 30a junction box into the main ring circuit... i came here for answers/advice not questions i am not sure i know how to answer lol

JohnW2 · 27 Sep 2017

rob4beer said:
I was thinking of creating a spur? i read that on google so a 30a junction box into the main ring circuit... i came here for answers/advice not questions i am not sure i know how to answer lol

Yes, provided that it is supplying only one single socket, then you could use 1.5mm² cable. One double socket would be much more debatable since, although some people feel that a double socket 'can' supply only 20A (just OK with 1.5mm² cable installed in an ideal fashion), it is certainly possible to plug in two 13A loads - i.e. 26A total, which is too much for 1.5mm² cable. Far better to just use 2.5mm² and avoid any discussions/arguments. Unless it were a fused spur, you are only allowed one (single or double) socket on a spur from a ring final circuit.

A 30/32A junction box would do the trick but if it is to be 'inaccessible', (e.g. under floorboards) it would have to be a 'maintenance free' JB.

Kind Regards, John

ban-all-sheds · 27 Sep 2017

JohnW2 said:
Unless it were a fused spur, you are only allowed one (single or double) socket on a spur from a ring final circuit.

Hmmmm.

JohnW2 · 27 Sep 2017

ban-all-sheds said:
Hmmmm.

Is that a reflection on the fact that there is no regulation which explicitly states that, or what? Electrically speaking, the cable of a 2.5mm² unfused spur (from a 32A ring) could theoretically become overloaded with anything more than two '13A outlets' on the spur (even with Method C) - let alone what I recently wrote about a 1.5mm unfused spur.

Kind Regards, John

flameport · 27 Sep 2017

JohnW2 said:
Yes, provided that it is supplying only one single socket, then you could use 1.5mm² cable.

BS7671 states otherwise.

Rings must be 2.5mm² minimum, unless mineral insulated cable is used.

JohnW2 · 27 Sep 2017

flameport said:
BS7671 states otherwise. Rings must be 2.5mm² minimum, unless mineral insulated cable is used.

I suppose one can debate whether the 2.5mm² minimum specified in 433.1.204 relates top spurs as well as the ring itself. Unlike the situation with the 2.5mm² ring cable in a 32A ring final,, the (downstream) overload protection provided by a single plug/socket is more than adequate for 1.5mm² cable. Nevertheless, all of us have advised the OP to use 2.5mm².

Electrically speaking, there is obviously nothing wrong with having a 1.5mm² spur from a ring final (or branch from a 32A radial) supplying one single socket, regardless of the rating of the circuit's OPD, provided only that the circuit's OPD gives the cable adequate fault protection (which it almost certainly will). However, I accept that being electrically satisfactory/safe and being compliant with BS7671 are not always the same thing! I personally probably wouldn't use 1.5mm² cable in this situation but I would be very happy to argue in front of anyone that it's use (as described) was compliant with Part P, even if not with BS7671.

Kind Regards, John

winston1 · 27 Sep 2017

Can 1.5 mm cable be used for radial circuits on a 20amp MCB?

JohnW2 · 27 Sep 2017

winston1 said:
Can 1.5 mm cable be used for radial circuits on a 20amp MCB?

If the cable is installed with Method C (CCC=20A) then, yes, of course - why would anyone think otherwise?

Kind Regards, John

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1 OR 1.5mm twin & earth cable for bathroom LED downlighters... discuss

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