Spur from shower circuit

[liquid]

I need to get power into my loft so that i can power a tv distribution amp, and to install ceiling sockets in a bedroom to supply a wall mounted tv

Unfortunatly i am unable to see any way of taking a spur from the ring main on the first floor, however i can get access to the shower supply.

The shower is fed by its own 40A fused CU, and the feed runs into a DP pullcord isolator before the shower.

My question is, is is permissable to take a spur before the DP isolator and run this through a 13A fused spur before connecting to a 2g socket in the loft? I can find nothing in the 16th ed regs that forbids this, but what do you guys think?

furthermore is it permissible to install 2 2g sockets in parallel (spur from a spur naughtyness) in this situation as in the following diagram.

if not, can i run each socket back to the 13A FCU in a (sort of ) radial configuration?

Untitled

• liquid
• 7 May 2008
• 2

thanks for your time
nick

 

[devans]

Don't showers run on radial circuits? (so adding to it could overload it?). Also thought it was bad news to add to circuits like showers and cookers... I'm no electrician, but lets see what the others think!

 

[oharaf]

No, don't try any of that!!!

You either need to find your ring and spur off (fused as you want more than 1 socket)

Or add a new circuit into your loft, either way, you are probably going to have to knock out some plaster work.

Do it properly, for your and everyone elses sake.

If you aren't sure pay a sparky, please

 

[ban-all-sheds]

Unfortunatly i am unable to see any way of taking a spur from the ring main on the first floor,

Why not? Where do the cables run?

My question is, is is permissable to take a spur before the DP isolator and run this through a 13A fused spur before connecting to a 2g socket in the loft? I can find nothing in the 16th ed regs that forbids this, but what do you guys think?

I think you'll struggle to get 2 x 6/10mm² cables into the switch terminals.

furthermore is it permissible to install 2 2g sockets in parallel (spur from a spur naughtyness) in this situation as in the following diagram.

Of course it is, if the spur originates from an FCU.

if not, can i run each socket back to the 13A FCU in a (sort of ) radial configuration?

Untitled

• liquid
• 7 May 2008
• 2

Your diagram already shows a radial - what do you think it is?

Don't showers run on radial circuits? (so adding to it could overload it?).

How does its radial nature mean it could become overloaded? As long as In <= Iz then it doesn't matter what you ad to it.

Also thought it was bad news to add to circuits like showers and cookers... I'm no electrician, but lets see what the others think!

It's not good practice.

 

[devans]

How does its radial nature mean it could become overloaded? As long as In <= Iz then it doesn't matter what you ad to it.

I see... yes that is pretty obvious!

 

[liquid]

My question is, is is permissable to take a spur before the DP isolator and run this through a 13A fused spur before connecting to a 2g socket in the loft? I can find nothing in the 16th ed regs that forbids this, but what do you guys think?

I think you'll struggle to get 2 x 6/10mm² cables into the switch terminals.

hmm hadn't thought of that. Given that a spur must be run using the same cable as the feeding circuit, this means 6mm². Presumably after the FCU i can use 2.5mm²?

if not, can i run each socket back to the 13A FCU in a (sort of ) radial configuration?

Untitled

• liquid
• 7 May 2008
• 2

Your diagram already shows a radial - what do you think it is?

sorry attached the wrong diagram, but you answered my question!

Also thought it was bad news to add to circuits like showers and cookers... I'm no electrician, but lets see what the others think!

It's not good practice.

Is that 'not good practice' as in DONT DO IT, or just not good practice?

 

[stargazer]

Well as it happens, we had an engineer round from MIRA to fix our electric shower a couple of weeks ago.
I installed it as a replacement just before Xmas, and it’s one of those with a faulty flow valve which made it screech and howl for a few seconds after you turned it on. Like a banshee having an orgasm. All fixed under guarantee, and is running nice and quiet now, but I digress...
I have a couple of shower downlighters, 25 Watts each, which come on when you pull the shower isolator cord. The shower is run from 6mm twin and earth, more or less clipped direct, and table 4D5A gives me the current carrying capacity as 47 Amps. My shower is 8.5 KW, which at 230V is 37 Amps. That gives me 10 Amps spare, so the way I figure it I could have over 2000 Watts of lighting in my shower if I wanted to. But no, I only have a couple of downlighters drawing 50 Watts, properly fused down to 3 Amps with a switched FCU, but I digress again...
Mr Mira says “turn the power on please”
So I do as I’m told.
Mr Mira says “Why did those lights come on when you pulled the cord – the circuit should only serve the shower.”
So I explain, having done the maths, that I consider the circuit is safe – 50 Watts of lighting isn’t much on top of 8,500 Watts of electric shower.
Mr Mira says “Well it isn’t recommended to do it like that.”
So there you have it, MIRA are saying you should not spur from a shower circuit, and my shower lights which have been happily running for 10 years are not allowed. Is there any truth in this? I don’t know.
All I know is he lost out on the cup of coffee I was going to make him, although to give him his due he did make a fuss of the cat.

 

[ban-all-sheds]

I've got a Redring, which also makes that noise. Probably the same valve from the same factory in China. But mine's out of warranty, so I'll live with it.

I did have a warranty repair a few years ago though, and the bloke who came to fix it expressed no concerns about the fan coming on when the shower isolator was turned on.....

 

[JohnD]

“Well it isn’t recommended to do it like that.”

... not allowed...

"Not recommended" is not the same as "not allowed"

 

[breezer]

its just bad practice, so as its bad practice you dont do it

 

[RF Lighting]

I'd pull you for it on a PIR


The exhaust fell off my van. Should I reattatch it with some bailing twine, or should I use a proper exhaust clamp?

 

[Click-Sure]

Red/Brown books are in the van, and I'm not one to quote from regs but IIRC, all water or space heaters above a certain wattage (quite low IIRC) are supposed to be fed from their own dedicated circuit.

Anyone with a book to had prove/disprove this?

 

[SeanT]

Seen this too, it's either 2 or 3 kW iirc.

 

[GaryMo]

Seen this too, it's either 2 or 3 kW iirc.

Isn't that just to discourage the use of heavy fixed loads on ring final circuits?

 

[stargazer]

Yes, isn’t in the OSG?

http://www.tlc-direct.co.uk/Book/6.3.2.htm

Fixed equipment such as space heaters, water heaters of capacity greater than 15 litres, and immersion heaters, should not be fed by a ring, but provided with their own circuits.

Although not explicitly stated, I suppose the above must cover electric showers as "fixed equipment", because it would be a bad idea to put them on a ring .

I cannot however see a problem with my shower lights, or Ban's extractor fan, and it is not tenable of RF to compare a properly designed multi-outlet radial circuit to repairing the broken exhaust of a motor vehicle with bailing twine.

I have no problem with spurring off a shower radial for low powered equipment which is integral to a shower enclosure, such as lights and extractor fans. However I would not spur off to power a completely unconnected circuit, which is what the OP wants to do. That I would regard as bad practice. Whether there is anything in BS7671 to prevent him from doing so is another matter…