If I install extra-low voltage wiring, such as bell wire, ethernet, transducer wiring, 12V power supplies for radios or similar, am I obliged to follow the latest wiring regs, specifically about metal clips to stop the wire getting in the way if its supports melt?
If this is out of scope of the regs, does it come into scope if a) it is done as part of a mains wiring installation or b) it is done by a qualified electrician?
The reason for metal clips is that a fireman got trapped and killed because he got tangled in falling cabes. Low voltage cables are just as likely to do this as mains ones.
My common sense approach is that if it is carrying high current, or is able to then yes, if its not ie aerials network cables etc, then no. It always needs thicker wire for low voltage in any case, since the voltage drop will be very big otherwise. I remember an experiment. I ran a car radio on a 12v supply and put a bulb on the supply at the radio end. If I used a photo transistor amplified and looked at the bulb you could not hear a thing on a short lead, but even just 1metre of cable was enough to allow you to hear distorted sound coming from the bulb. Brian
Absolutely agree. I was just asking whether the regs legally applied.
It's covered by BS7671 as the requirement there applies to "wiring systems" which means any "assembly made up of cable or bus bars and parts which secure and, if necessary, enclose the cable or busbars."
Whether you or anyone else is required by law to follow the regs is a separate and more complex question. OTOH it's not on the face of it within the building regulations so "they can't touch you for it". OTOH if you don't use fire-resistant clips and someone dies or is seriously injured as a result I'd hope (very possibly in vain) legal action wd follow that at least left you very much poorer. Bear in mind the internet has a long memory so you might after this thread struggle to argue "innocent error".
In real life I would worry more about wires that crossed doorways or ceiling than those along walls. But I am impressed that advice on this hasn't filtered through to networking instructions as opposed to the actual wiring regulations. As a matter of interest, I wonder if wires running along plasterboard or clipped to it with metal clips meet the regulations? Plasterboard is supposed to be somewhat fire resistant but existing installations may not always be thick enough to count.
The regs only require you to prevent /premature/ collapse of the wiring system. I don't think it's /premature/ if the wiring comes down 'cos the wall to which it's fixed comes down.
But some what easier to break than 2.5 T&E (or bigger) after a fire has destroyed a plastic clip, which would also have annealed the copper and removed all the insulation. Nasty all the same.
So I take it that the hardened pin and plastic cable clip fixings are no longer legal?
the size of copper depends on the current carrying capacity, not the insulation.
depends where
For a Cat5 cable the insulation makes up most of the cables tensile strength.
Expand?
Not if you stick them under the carpet or round the perimeter in trunking :-)
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