I have a power cable running to my garage (not installed by me). It
comes off a secondary consumer unit, runs under the floor and then out
through a hole punched in a vent, then up beside the downpipe, over the
top of the gate and in under the roof gap (concrete sectional garage).
The whole thing looks pretty kosher apart from the cable, it is standard
internal grey 3-core (about 3mm I think). I want to upgrade this, partly
so I can get it down from over the gate (problematic for carrying tall
things in) and run it over the ground (well, along the front of the
small step formed between the patio slabs and drive). Beavering around
the sheds turns up armoured cable of various ratings including external
but my understanding was that outside I should run cabling in trunking.
So can I replace the cable with this armoured cable or do I need to
install trunking? if the latter can I get away with some plastic variety
so I don't have to earth the metal stuff? and if so where do I buy it?
I sometimes wish the previous owner had buried it under the concrete
slabs thus inhibiting me from doing anything about it ;-)
Armoured cable can be run on its own. It is the indoor type of cable, as
used in the existing installation, that needs to have extra protection. For
that, I use black heavy duty 20mm round PVC conduit. There is also a cable
called Hi-Tuf that can be used for external surface mounting, which is much
easier to route than armoured cable. Personally, being a belt and braces
man, I would use Hi-Tuf and also run that through conduit along the edge of
the slabs, where it might expect to come in for more than the usual wear and
I was looking at that this morning and I think I'll be able to excavate
under the edge of the slab and recess the cable which should help that
aspect. I was also thinking of putting a junction box in just inside the
house wall since I don't see the point of running armoured cable all the
way back to the cu.
Only the small disadvantages of it being another joint to potentially
work loose, and of making cable-tracing a little less intuitive. For
these reasons I kinda prefer HiTuF for visible external runs - nicer to
work with where it comes into the CU, 'nearly' as resistant to likely
mechanical damage in typical domestick situations. F'r example, as we
redo the downstairs den I'll replace the existing 2.5mmsq T&E-with-HiTuf
outside which runs to the nearly-attached garage with a single length
of 6mmsq HiTuf, allowing an upgrade of the outgoing MCB from 20A to 32A
with voltage drop well under relevant limitses - since the garage/wshop
loads have noticeable switch-on surges and I want to be able to run
the 2kW quartz heater, vac, and dust-making powertool without doing
'how close am I to 20A+ at this point' stuff in my head ;-)
On 21 Feb 2004 00:18:12 GMT, email@example.com wrote:
[T] I was looking at different 'tough' cable options and was offered
what may of been 'HiTuf' as an 'as tough' alternative to armoured
(black, round, fairly rigid and sounded like HiTuf from memory ..).
I asked if it would equally resist a hit from say a spade or fork and
the guy said yes. He went and found a short length of the cable and
piece of metal, put the cable on the counter and clumped it with the
metal (I assume to demonstrate that it would take a blow from a
With the first blow he had nearly cut it in half ... I'll stick with
All the best ..
T i m
I must say I've heard this Hi-tuf recommended here and assumed it was
the same as FP200 or Fire-tuf, I've never heard of Hi-tuf. If it is
the same then it isn't really mechanically protected, it's fire alarm
cable, basically flex, but mildly tougher.
Maybe an example of Hi-tuf would help.
On Sat, 21 Feb 2004 09:40:34 GMT, firstname.lastname@example.org (Lurch)
[T] To me it looked 'like' armoured (silky deep black finish and quite
'stiff') but looking at the end it looked just like a thick sheathed
flex? I can't even remember if the cores were solid or not (I'd assume
they would be or multi stranded solid).
I found this ..
"Hituf multicore PVC cable is more robust than standard PVC sheathed
cables and provides a quicker, more economical alternative for:
General power, control and fixed wiring uses.
Temporary wiring on open sites."
"Temporary wiring on open sites" dosen't sound like it would be the
right thing for running power to a garage does it?
All the best ..
T i m
It's quite useful where you have to surface mount a cable outside, like
along a wall where it will be seen - it's quite easy to make a neat job
of, and rather less of an effort than Pyro, although more obtrusive.
*If God had wanted me to touch my toes, he would have put them on my knees
Dave Plowman email@example.com London SW 12
Well my job is done with Pirelli 35A armoured cable. It was forced on me
since tying up the old internal flex over the gate while I demolished
the column shorted it and blew the house CU unit fuse, but not the fuses
in the garage (a giveaway that one). So here I sit, aching and sore from
sitting under the house in a space too small for me fitting a junction
box, first attempt fails, screws too small, armed with some appropriate
spax screws it is up. Then the old cable needs to be cut (all house
power off, just in case) and cleaned back. That is two long crawls under
the floor and careful over the barely supported gas pipe. Then it is
enlarge the hole in the air brick to admit the armoured cable (pre
stripped). So back under (now with a head torch) and attempt to connect
them together in the junction box. A connection is made, but I can't get
the top over the armoured and I have forgotted to sleeve the earth
cable, sigh. So its out for some tape and a cable cutter for the armor
wires to cut the cable back some more and slap on some tape. 45 min
later and its done, so am I. But I have to run it into the garage, cut
it, cut it back again and wire it into the garage cu.
After a long soak in the bath and tea, the fuse is put back together
(after cleaning molten metal out first) and the power switched on, so
far so good, into garage, switch on, no bang! turn on lights, let there
be light! flick switch to make the sockets live, they work!
So I have the garage wired with armoured cable, but the gate post is
languishing. Why do things always toke so much longer than you expect?
Oh and it snowed on me while I was enlarging the air brick hole.
HiTuf is a normally insulated round PVC cable, with an additional outer
sheath of a much tougher plastic. The outer sheath protects against the
degrading effects of UV light when surface mounted outdoors and it provides
better mechanical protection than an ordinary cable. However, if you plan to
bury a cable in too shallow a trench, where it might be vulnerable to spades
or forks, then SWA is the stuff to use.
That's about right: it's (more than mildly) tougher than ordinary
T&E, UV resistant, suitable for clipping to the outside of 'ordinary'
domestic/light-industrial property (e.g. for feeding a bunch of
BS4343 sockets), but is *not* a replacement for SWA in situations where
there's a serious risk of mechanical damage. It's tougher than Fire-tuf,
with the jacket being designed to provide mechanical protection rather than
resistance to fire (and LSH): stripping it requires nontrivial effort, as
the construction goes: outer black jacket (not all that hard), inner white
not-much-plasticiser-in-this-PVC-(if-that's-what-it-is), in which the
'normal' PVC-insulated cores are in turn embedded. For burying, HiTuf
would need additional protection (a tough conduit). But HiTuf's a handy
addition to the armoury ;-) of cable types.
Others have pointed you at the TLC website; if you want a spare foot or
so, email me you physical address and I'll send you an offcut, in the
unlikely event your usual trade counters look at you blankly when you
mention the stuff next time you're in...
I normally put a rectangular junction box rated to IP68 on the oustide of
the wall, with a piece of conduit running back through the wall for the
cable from the house. That enables me to run the SWA straight down from the
bottom of the box. SWA does not bend easily and that is much easier than
running it through the wall and then down. If I were using Hi-Tuf, I would
run it right back to the CU, if possible.
Ok thanks for that, I'll have a better look at the situation and think
about the corners. In the present situtation with the flex there are two
90degree bends but running it at ground level should remove those though
there is a solid concrete pillar to consider.
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