Continueing on from my search for "black" T&E I'm probably going to end up
using the Hi-Tuf cable previously recommended. However I think a few
eyebrows were raised at the thought of wiring 12 x 50w mains halogens in
series. Basically I have an existing light fixture (3x80w spot) which I
intend to replace with a junction box. From this I plan to run a a single
cable about 20-22 metres long. Approx. every 1.5 metres along its length or
so there would be a junction box with a spur about 2m long with a 50w
halogen on the end.
Ignoring the practicalities of wiring ths upside down, 4m up in the air,
trying to conceal the cable and drilling through timbers 12" thick what are
the electical implications? Will it work?
I've googled and can't find anything particularly relevant or imformative.
Anyone got any ideas?
As others have pointed out, they'll actually be in parallel - with the cable
taking progressively less of the load the further along it you go.
12 x 50 watts (600 watts = 2.5 amps @ 240v) is actually a pretty light
electrical load. I don't know what size your cable is, but 1mm^2 or above
should handle it quite easily.
[It would, of course, be a totally different story if they were LV
halogens - since you'd then be dealing with a total current of about 50
Series wiring is like fairy lights - ie volts have to pass through one
lamp before the next. So if you wired up 12 identical mains halogens like
this, they'd be running on 20 volts or so and be rather dim. There's also
the problem that if one or more blows, you'd not know which it was, as
they'd all go out.
All equipment designed to run off 230 volts is parallel wired.
*Why is 'abbreviation' such a long word?
Dave Plowman email@example.com London SW 12
I hope you mean in parallel, otherwise you won't have much light. :)
12 x 50w = 600W, a fairish load. What else is on the circuit? Fused?
My problem with this is the number of joints you will be making; twelve
for the lights plus one for the existing connection. Can you run the
cable up and down to each light to minimise joints - this would be
considered good practice.
To reduce voltage drop, which may cause the light at the furthest end of
the chain to be slightly dimmer, I'd suggest using 1.5mm2 cable.
"Mike Tomlinson" wrote
| >However I think a few
| >eyebrows were raised at the thought of wiring 12 x 50w mains halogens in
| I hope you mean in parallel, otherwise you won't have much light. :)
| 12 x 50w = 600W, a fairish load. What else is on the circuit? Fused?
However IEE regs require each lighting point to be assessed at 100W minimum,
or actual load if greater. So the 12 points would represent a pretty much
fully loaded 6A lighting circuit. And I don't know if the dinky mains
halogens are permitted under the regs (or allowed in the manufacturer's
instructions) to be fused at >6A - SES and SBC aren't.
I was under the impression that the 100W allowance is for ES and BC
fittings. If the fitting takes a specific size bulb (such as a fluorescent
tube or halogen bulb) then you could substitute the maximum wattage that the
fitting is capable of.
"Christian McArdle" wrote
| > However IEE regs require each lighting point to be assessed at
| > 100W minimum, or actual load if greater.
| I was under the impression that the 100W allowance is for ES and BC
| fittings. If the fitting takes a specific size bulb (such as a
| fluorescent tube or halogen bulb) then you could substitute the
| maximum wattage that the fitting is capable of.
I would always work on the 100W per point minimum on the basis that a
fitting might be substituted at a later date with one having an
However IIRC the OP is talking about a commercial installation where the
Electricity at Work Regs will apply, so a 16A lighting circuit will be
possible if the individual fittings allow use on a 16A cct and the terminals
are adequately sized. The requirement that any alterations to the
installation will be carried out by a 'competent' person should mean that
SBC/SES luminaires aren't substituted contrary to Regs. I don't like 16A
lighting in domestics because of the liklihood that SBS/SES luminaires will
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