I want to wire a fused spur from a UPS in one room to a double socket (BS1363) in the next room for convenience in transferring telephone and IP equipment from mains to UPS. Because of existing holes in the wall and trunking I want to wire it with 1mm^2 T&E. Given it is supplied via a marked 3A fused double pole switch, is this ok?
Is this wired from the house wiring, or from the output of the UPS?
If it's a spur off the ring then the TLC calculator says you can go up to
80m in 1mm2 with a 3A load. The 3A fused connection unit will ensure you don't overload the ring.If it's from the output of the UPS then it's more or less a wall mounted extension lead. The UPS will limit the output current.
There's a bunch of stuff in 18th edition Amendment 2 [which I don't have] about 'prosumers' where you are both consuming and generating power - think solar inverters and batteries. I think technically the UPS would count as one of those, but if you're not backfeeding or mixing with the house wiring then I don't think it's significnat here - you're just making a longer wire from the socket on your UPS. I would ensure that any such trailing socket is isolated from other electrical systems - eg don't wire the earth of such a socket to any other earth, and don't share socket boxes with your mains supply.
Theo
In real world use, it will be fine, but it will not meet BS7671, as power conductors need to be a minimum of 1.5mm for the live conductors. Be aware tapping off from a socket that already has 2 x 2.5mm cables in it is not great, the 1mm can easily slip out, no mater how tight you screw it down, so it will need doubling over. To do it properly, just use 2.5mm T+E.
Yes, and at the UPS end the connection is one of those trailing IEC kettle-type sockets which cannot be inadvertently plugged into the mains. I always worry about people replacing the 3A fuse with a 13A one. I think spurs should be supplied with a choice of permanently marked fuse holders. The UPS could theoretically supply up to 6A into an inductive load (1500VA) but not for long.
It isn't connected to a ring, just to the o/p of a UPS. But I am not sure if I can get 1.5mm T&E into my existing trunking. The route I am using currently carries redundant telephone extension wiring. Is BS7671 a mechanical or electrical specification? I suppose I could put ferrules on the 1mm conductors? Or Wagoes in the backbox?
I thought you was a radio ham.
Drilling the hole in the wall out bigger is not easy, because the fairly loose irregular slate stones tend to slip out of place and jam large masonry bits which act more as jack hammers than drills and not good for your wrists if they jam.
What about using a Schuko socket? That would certainly discourage anyone plugging is some other UK appliance (like the vacuum cleaner).
Since this is fed from the output of the UPS and not direct from the mains, it is arguably not even fixed wiring in the conventional sense. So the 1mm^2 will have adequate fault protection by the 3A fuse.
(and the UPS itself will likely have overload protection)
If you have trunking you could wire that in singles rather than T&E, which will give you much more space to play with.
BS7671 (aka "The Wiring Regs" is principally an electrical spec - but touches lots of bases on mechanical, thermal, emc/emi etc.
I suppose I could put ferrules on the 1mm
Yup you can also get sockets these days with wago style terminals built in instead of traditional screw terminals.
Turns out Amendment 2 specifically excludes UPSes as a 'Prosumer Electrical Installation' (PEI):
823 PEI CONCEPT [...] An uninterruptible power supply (UPS) is not considered to form part of a PEI as the purpose of a UPS is only to supply downstream critical loads and is not capable of reverse feeding the public network and/or current-using equipment in the upstream part of the installation.So as it says, as long as you keep the UPS output separate from your mains electrical system it's a standalone thing and not covered by BS7671.
Theo
It's well worth getting an SDS drill with a built-in clutch - I did just that, some years ago, when I needed to core drill a vent hole, while standing on a ladder. My existing mains drill would have done the job, but I feared for my wrist and for my stability on the ladder, without that safety clutch. With it, there is very little kick-back.
I've just drilled a 52mm hole through a cavity wall, using an SDS and diamond core bit. I'm not sure if the bricks are especially hard or the bit poor quality, but there's no way I could have done it from a ladder. Took about 2 hours, heavy work.
It sound like the bit. Even hard-bricks don't normally take that long.
The vent was a 5" hole, just below the 1st floor eaves and with a very heavy SDS drill ... it was very hard work. I have done others from inside (this one was in too tight a space for that), but sometimes up on a step ladder.
So far, one bathroom vent, one toilet vent, two soil pipes, seven waste pipes, one tumble dryer vent, one cooker hood vent, three underfloor vents, one boiler flue and one condensate drain. I think my SDS has more than paid for itself, without including any of the other things I've used it for or any time its been used somewhere other than at home.
The only time I've had that kind of trouble with core drill was I inadvertently had the core turning the wrong way. Clockwise/anticlockwise is too easy to change on my Dewalt SDS. :(
Could be - it was a medium-cheap from Toolstation. The drill is a 1kW Lidl - seems good and the clutch works.
On hindsight - and this isn't that well thought through - I reckon drill a
10mm pilot from inside, then carry on inside right through to within a couple of inches. Then finish off the last bit from the outside, using the pilot hole as guide.Good grief - that's good going!
I did think that and checked. Weird thing was when I tried it counterclockwise for some reason, it suddenly appeared to cut though an inch or so. Not sure what that was about. Couldn't use it that way for long in any case - the core bit would simply unscrew from the shank. Don't ask how I know :-)
Just rearrangements of the bathroom and kitchen, addition of a second toilet and fitting underground under-floor vent pipes before pouring a slab for a conservatory. It's amazing how many things need holes through the walls.
That's very reassuring - thanks for looking it up!
I think that's very good advice - it is rarely in the specs of cheap ones, I suppose I have to buy a well known make!
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