In article ,
Some wholesalers will sell the larger SWA by the metre, but
I doubt they'd break into a drum of the smaller stuff, but
you could ask. I once got a drum very cheaply because the
drum side had broken off and they just wanted it out of
the warehouse before it spewed all over the floor.
Thanks for the offer, only need 3 core. BTW, what does the 240mm refer to?
I have some rear garden wall lights and an exterior plug socket. The power
is taken from a junction box on the outside of my house which feeds the
garage. Whoever installed the rear lights (I have only just moved in) used
normal white PVC cable from the JB to the fence. It goes underground for
about 6 feet and has been hit by some workmen who installed some gates so
need to replace it with SWA.
Would I need 1.5mm or 2.5mm?
Assuming the "240" is cross sectional area of each core, I make that
about 2/3" diameter - what the **** do you connect up with that?
(If the 240 is the diameter of each core, my question still stands but
I shall be expecting an answer like "power station to grid"!)
The cross sectional area of *each* conductor...
(240mm being well in excess of anything you would ever encounter in a
Are you sure you need three core? (given that you can use the armour for
your protective conductor (i.e. earth)
That depends on the total design load (sounds like 16A ought to be
adequate in this case) and the length of the cable. When calculating
voltage drop, don't forget to include the internal cable run that gets
as far as your junction box (which I hope is a exterior grade waterproof
All explained here:
Something that needs *lots* of current!
If it is a Ali cable then that will carry 386A per phase, or 520A per
phase for a copper one. (at 90 deg C, clipped direct)
I don't have a table for anything that large!
In article ,
Martin Bonner writes:
No, it will be a few hundred kilowatts. I think that was the
size of feed we had laid when we went from 600kW to 900kW supply
(they always just added an extra cable for the extra, never a
new cable for the lot). Eventually we got to 2MW (which required
a new substation at some point), and then moved premises!
I've got a piece single core 150mm armoured here (about 1/2"
diameter conductor). Being single core, the armour is copper
as it mustn't be magnetic. Oh, and it's for 11,000V...
I think you are confused about the question I was asking. John Rumm's
table gave 386A per phase for 240mm2. If we assume (invalidly) one
phase, that's about 100 kW, so I think you were answering for the case
where the 240 is cross sectional area.
My parenthesised question was for when the 240 is the /diameter/;
which implies a cross sectional area of around 45,000 mm2.
If the maximum current is linear with the diameter then 45,000 mm2
would be good for a MW at 240V. I think the maximum current ought to
grow a little faster than linear (surface area to dissipate heat is
linear with diameter, but resistance falls as 1/D2 - so less heat to
dissipate), Even so, it probably wouldn't be able to take a sensible
power station at 240V.
Of course, that gives you a bit more power!
I remember going to the Ford Museum at Dearborn, and seeing an early
factory generator. I can't remember whether it was for the Ford
plant, or one of Edison's. What I do remember is that the current
meter went up to 1 MA (and yes, I do have the case of that right!).
You wouldn't want a one ohm junction resistance in that circuit
It was just a bit left over from a server room upgrade. 240 is the
csa of each core. Never heard of cable sizes relating to o.d. though.
But i am often wrong [as my wife keeps reminding me]
Takes a bit of bending though