Putting power sockets in the loft

[SUNRAY]

With regard to to the heater I'm planning on putting more insulation down and adding to the 100mm (approx) already up there and possibly using something like the superfoil bubble stuff stapled to the rafters. Should provide an ambient temperature up there.

Previous owner boarded part of the loft and put boards directly across the joists compressing what insulation there was up there so need to remedy that. Our house is a detached house and was built in 2000.

I added 100mm fibreglass between the rafters then tacked 4mm ply to form a sloping ceiling & painted it light blue (Sky blue). If I were doing it again I'd be using something like kingspan Celotex rather than glass fibre. I elected to reduce the insulation in the joists to let some heat in, I never did work out if it was the right thing to do.
At the time I had some recovered plastic trunking and a load of matching sockets so screwed a 10ft length to the wall with maybe 10 sockets (I just used up short pieces of pre-used lid so that dictated the irregular spacing. During the construction of the benches I had several drills, light, vacuum, heater, etc running.
We (I) installed two 3.2m*0.8m baseboards in an L shape with expectation of expanding significantly up to 4.8m*4.8m square loop in stages. sadly circumstances meant not much scenic work was completed.

 

[JohnD]

Kingspan used to say that you could lay foam slabs on the loft joists, and put chipboard on top of that

They deleted the recommendation shortly after the Grenfell disaster.

 

[Harry Bloomfield]

At the time I had some recovered plastic trunking and a load of matching sockets so screwed a 10ft length to the wall with maybe 10 sockets (I just used up short pieces of pre-used lid so that dictated the irregular spacing. During the construction of the benches I had several drills, light, vacuum, heater, etc running.
We (I) installed two 3.2m*0.8m baseboards in an L shape with expectation of expanding significantly up to 4.8m*4.8m square loop in stages. sadly circumstances meant not much scenic work was completed.

Similar here - the underside of the tiles were visible, mortared on the underside, which constantly crumbled down at every slight breeze. I boarded over the insulation, squeezed in flame retardant polystyrene sheet between the rafters, added a Velux window, and added stud walls, to each low side, with an access panel, all again tightly insulated. I diverted the no longer needed, immersion heater supply, for both lighting, and power up there, but made it easy to restore, should the boiler fail.

Around the sides, I built work benches, and added numerous sockets with maybe 15 to the main electronics bench, then a section of radio ham space. It all used to be crammed, into the small bedroom, until kids came along and I had to vacate.

 

[JohnD]

It's a pity Foamglas is not readily available in UK

Some people would be surprised to hear there is an insulating foam slab that is non-flammable, rot proof, waterproof, and does not emit toxic fumes in a fire.

 

[SUNRAY]

Kingspan used to say that you could lay foam slabs on the loft joists, and put chipboard on top of that

They deleted the recommendation shortly after the Grenfell disaster.

I'm confused at that, having used kingspan as protection when using a blowtorch.

 

[JohnD]

Grenfell Tower Inquiry: Kingspan employees kept fire test results 'secret'

Andrew Pack, a senior executive at Kingspan, gives evidence at a public inquiry into Grenfell Tower.

www.bbc.co.uk

 

[SUNRAY]

...Around the sides, I built work benches, and added numerous sockets with maybe 15 to the main electronics bench, then a section of radio ham space. It all used to be crammed, into the small bedroom, until kids came along and I had to vacate.

That's the way to do it and it was my plan until the model railway suddenly came on the scene.
Instead I had to build an extension, 16ft*8ft. The bench being a U shape across one end with ~16ft of trunking a foot above completely filled with sockets, that must have been 40 or so, and another strip ~4ft at a higher level each side. Again all recovered from a rip out.

At least the extension as a scramble bike workshop and the 'prepared' loft as a home office sold the house for me about 5 years later.

 

[SUNRAY]

Grenfell Tower Inquiry: Kingspan employees kept fire test results 'secret'

Andrew Pack, a senior executive at Kingspan, gives evidence at a public inquiry into Grenfell Tower.

www.bbc.co.uk

That has to be different stuff to what I used, at times I laid assembled copper pipe and fittings on it to solder. I'm not saying it wasn't affected but it didn't catch fire or fume that I was aware of.

 

[BlueLoo]

If done properly, ie with >270 mm insulation and an air gap under your loft boards and the same insulation everywhere else, and with the loft properly ventilated, it's going to be a very cold and unheatable space in the winter and the clear nights.

Also, you, your floorboards, your tabling for the scenes, your equipment etc are going to add a significant load to the rafters which may not be really designed for it.

Something to consider.

 

[SUNRAY]

...

Also, you, your floorboards, your tabling for the scenes, your equipment etc are going to add a significant load to the rafters which may not be really designed for it.

Something to consider.

Rather stupidly I'd assumed this had already been investigated.

 

[Ragnar_AT]

Even a heater could be plugged into the lighting circuit. 6 A at 230 V (it‘s a good idea to use the nominal voltage for calculations) is 1380 W, so a 1000 W heater would leave plenty of power for lights in the rest of the house. Obviously in this specific case the old immersion heater supply is the much better choice.

 

[SUNRAY]

Even a heater could be plugged into the lighting circuit. 6 A at 230 V (it‘s a good idea to use the nominal voltage for calculations) is 1380 W, so a 1000 W heater would leave plenty of power for lights in the rest of the house. Obviously in this specific case the old immersion heater supply is the much better choice.

You are not wrong.
Realistically the heater will usually be quoted by manufacturer as 220-240V and the power quoted at the highest specified voltage.
A rating of 1.5KW for example is likely to be ~6.25A at 240 V or ~5.99A at 230V (a touch less if loop resistance is taken into account Although that would theoretically be fine on a 6A MCB I would strongly recomment not to, or for that matter the 1KW either, as the inrush of switching other lights on in the property could feasibly trip the MCB running right at its rating.

I went to a house with 3* 500W outdoor floodlights on the downstairs light circuit to investigate why the kitchen fluorescent light kept tripping the MCB...

 

[JohnD]

I have a small unheated WC where I connected a 350W heated towel rail to the lighting circuit. No nearby sockets.

It's controlled using a spare programmable CH stat I happened to have, the load is within its rated switching capacity. So it turns higher during daylight hours when the solar panels might be working.

 

[Steven Prentice]

Coming back to this thread for a look, seam to have created a discussion over lighting circuits.... as far as the cable and consumer units are concerned they are just circuits with thinner or thicker wires and larger or smaller protective device ratings.

Mentioned earlier, I wouldn't put a heater on a lighting circuit even if my sums thought it would stand up to it. Lighting cable has half a chance to run under insulation in the loft - particularly DIY insulation installs - roll it out and job done - so could over heat quite happily.

Also a note here, UK traditionally had 240V supply, Europe 220V or 230V, all harmonised so we could use equipment from the EU all over. Now we are nominally 230V -6% / +10% which gives a maximum voltage of 250V+... so above calcs for current might have to take account of this too (My house is about 244V supply from an older pole mounted transformer, which might, or might not be set to 230V or 240V). Just a thought.

Anyway - no heater on a 6A supply is what I am suggesting.

 

[BrettRogersUK]

Hi All,

Thanks for the constructive discussion in this thread, been a pleasure to read.

I now have a another question related to the original topic.

The immersion heater switch has a back box recessed in the wall. The wire that I need to being down from the loft needs to go in some trunking down to an external pattress box.

How do I put the external pattress box over the recessed back box where the original wires are?

Thanks,

Brett