Just talking to my next door neighbour. He's currently got a very long
extension cable strung across the road, on top of the tarmac, between his
house and his lambing shed. Call it 100m to be on the safe side.

He's going to run armour cable through the gulley under the lane, but is
wondering what size. Reckons he'll chuck a 20A RCD on the house end -
it's not much more than a bunch of light bulbs and the odd heat lamp, but
it'd be nice to have a socket there he didn't have to worry about using.

He was thinking 4mm2, but wondering if 6mm2 would be wise.
I found a cable calculator on t'web, and it reckoned 10mm2 for 16A or
above, 6mm2 for 13A.

What think the assembled multitudes?

On Fri, 03 Apr 2015 18:09:50 +0000, Adrian wrote:

What think the assembled multitudes?

100m is a fair old run, but OTOH, 6mm^2 is a tidy thickness of cable.
Seems OTT on the face of it. Are you sure he's not planning to grow skunk?

Adrian wrote:

He's going to run armour cable through the gulley under the lane, but is
wondering what size. Reckons he'll chuck a 20A RCD on the house end -
it's not much more than a bunch of light bulbs and the odd heat lamp, but
it'd be nice to have a socket there he didn't have to worry about using.

He was thinking 4mm2, but wondering if 6mm2 would be wise.
I found a cable calculator on t'web, and it reckoned 10mm2 for 16A or
above, 6mm2 for 13A.

What think the assembled multitudes?

As it's a lighting circuit, you're not allowed as much of a voltage
drop, and if he's going for a 20A circuit for some sockets, the whole
circuit should be designed for the voltage drop at max current.

The TLC calculator reckons 16mm^2 SWA for 100m, expensive about £370

If he dropped the house-end MCB to 10A, he could use 10mm^2 instead,
still £240

"Andy Burns" wrote in message
o.uk...
Adrian wrote:

He's going to run armour cable through the gulley under the lane, but is
wondering what size. Reckons he'll chuck a 20A RCD on the house end -
it's not much more than a bunch of light bulbs and the odd heat lamp, but
it'd be nice to have a socket there he didn't have to worry about using.

He was thinking 4mm2, but wondering if 6mm2 would be wise.
I found a cable calculator on t'web, and it reckoned 10mm2 for 16A or
above, 6mm2 for 13A.

What think the assembled multitudes?

As it's a lighting circuit, you're not allowed as much of a voltage drop,
and if he's going for a 20A circuit for some sockets, the whole circuit
should be designed for the voltage drop at max current.

The TLC calculator reckons 16mm^2 SWA for 100m, expensive about £370

If he dropped the house-end MCB to 10A, he could use 10mm^2 instead, still
£240



Is that price based on TLC prices?

--
Adam

ARW wrote:

"Andy Burns" wrote:

The TLC calculator reckons 16mm^2 SWA for 100m, expensive about £370

If he dropped the house-end MCB to 10A, he could use 10mm^2 instead, still
£240

Is that price based on TLC prices?

Yes, and probably steep delivery for such a weight, I don't have access
to 'trade' prices ... sounds like it'd be worth an ask?

On 03/04/2015 19:09, Adrian wrote:
Just talking to my next door neighbour. He's currently got a very long
extension cable strung across the road, on top of the tarmac, between his
house and his lambing shed. Call it 100m to be on the safe side.

He's going to run armour cable through the gulley under the lane, but is
wondering what size. Reckons he'll chuck a 20A RCD on the house end -
it's not much more than a bunch of light bulbs and the odd heat lamp, but
it'd be nice to have a socket there he didn't have to worry about using.

He was thinking 4mm2, but wondering if 6mm2 would be wise.
I found a cable calculator on t'web, and it reckoned 10mm2 for 16A or
above, 6mm2 for 13A.

What think the assembled multitudes?

If you want to stay within the 5% allowable voltage drop it ought to be
10mm.

6mm2 has a total voltage drop of 7.3mV / A / m
At 100m and 20A this gives 14.6V which is 6.3%

10mm has a total voltage drop of 4.4mV / A / m
At 100m and 20A this gives 8.8V which is 3.8%

He could use a 16A MCB and 6mm2 cable but only just!

I'm not sure if these are such hard and fast rules, the reason I say
that is it is the design of a circuit that has to be with these rules,
but the choice of MCB is there to protect the cable and associated fittings?

100m x 6mm2 cable is expensive, 2-core is £165 + VAT in TLC!
100m x 10mm2 cable for 2-core is £240 + VAT, in terms of copper it
almost seems good value!

Fredxxx wrote:

If you want to stay within the 5% allowable voltage drop

3% for lighting circuits.

On 03/04/2015 20:14, Andy Burns wrote:
Fredxxx wrote:

If you want to stay within the 5% allowable voltage drop

3% for lighting circuits.

Ah - thanks.

On 03/04/2015 20:14, Andy Burns wrote:
Fredxxx wrote:

If you want to stay within the 5% allowable voltage drop

3% for lighting circuits.

Which I assume is based on output of incandescent lamps falling
dramatically with reduced voltage.

I wonder if the regs need to add an extra case for LED or CFL lighting
installations where the SMPS built into the lamp is much more tolerant
of voltage variations?

--
Mike Clarke

On 03/04/15 21:30, Mike Clarke wrote:
On 03/04/2015 20:14, Andy Burns wrote:
Fredxxx wrote:

If you want to stay within the 5% allowable voltage drop

3% for lighting circuits.

Which I assume is based on output of incandescent lamps falling
dramatically with reduced voltage.

I wonder if the regs need to add an extra case for LED or CFL lighting
installations where the SMPS built into the lamp is much more tolerant
of voltage variations?


As I implied, I would not get too excited over volt drop on a rather
special case circuit like this as long as it does not compromise safety.

The main two problems the OP has are ensuring disconnection times and
also, given the farming nature of the application, he probably has some
additional problems concerning provision of earthing - which is way
outside of my knowledge.

Animals are more sensitive to voltage gradients through the ground
(partly because they span a greater distance of ground and partly
because they are usually standing barefoot in mud).

It might be actually worth subbing this one out to an electrician with
knowledge of farm requirements.

The OP's friend could still do the laborious work of laying the cable
(after seeking advice on the spec) leaving the electrician to connect up
and test.

Tim Watts wrote:

As I implied, I would not get too excited over volt drop on a rather
special case circuit like this as long as it does not compromise safety.

How sensitive are heat-lamps to voltage drop? Do lambs appreciate
CFLs/LEDs?

On 03/04/2015 20:14, Andy Burns wrote:
Fredxxx wrote:

If you want to stay within the 5% allowable voltage drop

3% for lighting circuits.



But LEDs don't care if you drop 50%.
So if its for lighting why would it matter?

The heat lamps won't care either.

Some motors might complain if the drop is high.


Why do lighting circuits only allow 3% these days?

Dennis@home wrote:

Andy Burns wrote:

Fredxxx wrote:

If you want to stay within the 5% allowable voltage drop

3% for lighting circuits.

Why do lighting circuits only allow 3% these days?

Of course LEDs, CFLs etc won't care about voltage, but what if someone
changes back to incandescents?

On 03/04/15 22:34, Andy Burns wrote:
Dennis@home wrote:

Andy Burns wrote:

Fredxxx wrote:

If you want to stay within the 5% allowable voltage drop

3% for lighting circuits.

Why do lighting circuits only allow 3% these days?

Of course LEDs, CFLs etc won't care about voltage, but what if someone
changes back to incandescents?


They'll run a bit dim.

That is why, although contrary to the regs, I would not bother too much
about a couple of % discrepancy on the volt drop - it's not leading to
an unsafe condition.

On 03/04/2015 22:34, Andy Burns wrote:
Dennis@home wrote:

Andy Burns wrote:

Fredxxx wrote:

If you want to stay within the 5% allowable voltage drop

3% for lighting circuits.

Why do lighting circuits only allow 3% these days?

Of course LEDs, CFLs etc won't care about voltage, but what if someone
changes back to incandescents?


They will last longer, be a bit redder, a bit dimmer, that's about it.

On 2015-04-03, Andy Burns wrote:

Fredxxx wrote:

If you want to stay within the 5% allowable voltage drop

3% for lighting circuits.

Hmm, some random questions about the difference...

What's the rule for a power circuit with a fused spur with wired-in
lighting? What if the fused spur with fixed lighting is added later?

Why are lights on a lighting circuit different from portable lights
plugged into a power circuit?

On 03/04/15 19:09, Adrian wrote:
Just talking to my next door neighbour. He's currently got a very long
extension cable strung across the road, on top of the tarmac, between his
house and his lambing shed. Call it 100m to be on the safe side.

He's going to run armour cable through the gulley under the lane, but is
wondering what size. Reckons he'll chuck a 20A RCD on the house end -
it's not much more than a bunch of light bulbs and the odd heat lamp, but
it'd be nice to have a socket there he didn't have to worry about using.

He was thinking 4mm2, but wondering if 6mm2 would be wise.
I found a cable calculator on t'web, and it reckoned 10mm2 for 16A or
above, 6mm2 for 13A.

What think the assembled multitudes?


https://www.tlc-direct.co.uk/Technic...ltageDrop.html

has a handy calculator.
I do not have my tables at hand, but for a 100m at 20A, he's likely to
need 16mm2 3 core SWA.

Why?


Because of either the volt drop or the ability to trip the supply side
breaker in quick enough time on a dead short (L-E or L-N).

If he came down to a 16A breaker, he'd be OK with 10mm2.

OK - for his purposes you could say "sod the volt drop" but you do still
want the breaker to trip correctly under fault conditions.

If you said sod the volt drop, 6mm2 at 16A should be OK. 4mm2 is too weedy.



Given the large cost difference between differing cable sizes for 100m
reels, it might be worth him evaluating if he really needs go that high,
or if 6A is good enough. That's still plenty of lamps. Not sure how
powerful the heat lamps are?

Given me a day or two and I will have access to my book and could tell
you for sure.

On 03/04/2015 19:09, Adrian wrote:
Just talking to my next door neighbour. He's currently got a very long
extension cable strung across the road, on top of the tarmac, between his
house and his lambing shed. Call it 100m to be on the safe side.

He's going to run armour cable through the gulley under the lane, but is
wondering what size. Reckons he'll chuck a 20A RCD on the house end -
it's not much more than a bunch of light bulbs and the odd heat lamp, but
it'd be nice to have a socket there he didn't have to worry about using.

He was thinking 4mm2, but wondering if 6mm2 would be wise.

Probably way undersized for a 20A circuit.

I found a cable calculator on t'web, and it reckoned 10mm2 for 16A or
above, 6mm2 for 13A.

What think the assembled multitudes?

For starters have a look at:

http://wiki.diyfaq.org.uk/index.php?...ricity_outside

There is a section there on cable choice.

If you work back from the allowable voltage drop of 3% of 230 or 6.9V,
divide that by the design current and the circuit length, and you should
have the maximum allowable voltage drop per amp per metre

So 6.9 / 100 / 20 = 0.00345 so you can afford to drop no more than
3.45mV per meter of SWA cable.

From the table he

http://wiki.diyfaq.org.uk/index.php?...de#SWA_Cab le

That says you will need 16mm^2






--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

"John Rumm" wrote in message
o.uk...

So 6.9 / 100 / 20 = 0.00345 so you can afford to drop no more than 3.45mV
per meter of SWA cable.

From the table he

http://wiki.diyfaq.org.uk/index.php?...de#SWA_Cab le

That says you will need 16mm^2


Or 10mm for a 4% drop at 20A which was good enough for the 16th edition.

And there are small changes to calculation Iz in the 3rd amendment with the
introduction of Cmin.

--
Adam

ARW wrote:

10mm for a 4% drop at 20A which was good enough for the 16th edition.

Yes, but where's he going to find 100m of red & black 10mm^2 SWA now :-P

On Saturday, April 4, 2015 at 8:11:05 AM UTC+1, Andy Burns wrote:
ARW wrote:

10mm for a 4% drop at 20A which was good enough for the 16th edition.

Yes, but where's he going to find 100m of red & black 10mm^2 SWA now :-P

Off a farm somewhere... this much copper needs to be fully hidden so it stays there.


NT

On Saturday, 4 April 2015 09:21:23 UTC+1, wrote:
Off a farm somewhere... this much copper needs to be fully hidden
so it stays there.


There were some nice farm electrics in the recent episode of BBC The Ladykillers involving rats in the potato barn.

Owain

On Saturday, April 4, 2015 at 9:21:23 AM UTC+1, wrote:
On Saturday, April 4, 2015 at 8:11:05 AM UTC+1, Andy Burns wrote:
ARW wrote:

10mm for a 4% drop at 20A which was good enough for the 16th edition.

Yes, but where's he going to find 100m of red & black 10mm^2 SWA now :-P

Off a farm somewhere... this much copper needs to be fully hidden so it stays there.


In fact given the cost I'd look at going aluminium. Note al does need larger conductors than cu, and end connectors designed specifically for al.


NT

On 04/04/2015 08:11, Andy Burns wrote:
ARW wrote:

10mm for a 4% drop at 20A which was good enough for the 16th edition.

Yes, but where's he going to find 100m of red & black 10mm^2 SWA now :-P

As has been mentioned many times in the past, the conductor colours tell
you nothing since the switch-over grace period spanned the move from
16th to 17th editions. So new colours on a 16th edition install are fine
as are old colours on a 17th edition one.

--
Cheers,

John.

/================================================== ===============\
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|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

Adrian wrote:
Just talking to my next door neighbour. He's currently got a very long
extension cable strung across the road, on top of the tarmac, between his
house and his lambing shed. Call it 100m to be on the safe side.

He's going to run armour cable through the gulley under the lane, but is
wondering what size. Reckons he'll chuck a 20A RCD on the house end -
it's not much more than a bunch of light bulbs and the odd heat lamp, but
it'd be nice to have a socket there he didn't have to worry about using.

He was thinking 4mm2, but wondering if 6mm2 would be wise.
I found a cable calculator on t'web, and it reckoned 10mm2 for 16A or
above, 6mm2 for 13A.

What think the assembled multitudes?

How about stepping it up to 2,400V and then stepping it down at the far end?

I can think of a lot more ways of doing it as well . . .

Bill

On 03/04/2015 21:24, Bill Wright wrote:
Adrian wrote:
Just talking to my next door neighbour. He's currently got a very long
extension cable strung across the road, on top of the tarmac, between
his house and his lambing shed. Call it 100m to be on the safe side.

He's going to run armour cable through the gulley under the lane, but
is wondering what size. Reckons he'll chuck a 20A RCD on the house end
- it's not much more than a bunch of light bulbs and the odd heat
lamp, but it'd be nice to have a socket there he didn't have to worry
about using.

He was thinking 4mm2, but wondering if 6mm2 would be wise.
I found a cable calculator on t'web, and it reckoned 10mm2 for 16A or
above, 6mm2 for 13A.

What think the assembled multitudes?

How about stepping it up to 2,400V and then stepping it down at the far
end?

I can think of a lot more ways of doing it as well . . .

That was one of my thoughts, well, more of making use of a transformer
to make 230-0-230 as most cables are rated for that anyway. That would
1/2 current and 1/4 the cross-sectional area required.

But the cost of 2 suitable transformers would be rather prohibitive.

Another thought was to use 4 core, and to load one pair such that
voltage drop was within 3% for lighting, and use the other within a 5%
drop for everything else.

If it was any further than 100m it might have been worth considering.

In message , Bill Wright
writes
Adrian wrote:
Just talking to my next door neighbour. He's currently got a very
long extension cable strung across the road, on top of the tarmac,
between his house and his lambing shed. Call it 100m to be on the
safe side.
He's going to run armour cable through the gulley under the lane,
but is wondering what size. Reckons he'll chuck a 20A RCD on the
house end - it's not much more than a bunch of light bulbs and the
odd heat lamp, but it'd be nice to have a socket there he didn't have
to worry about using.
He was thinking 4mm2, but wondering if 6mm2 would be wise.
I found a cable calculator on t'web, and it reckoned 10mm2 for 16A or
above, 6mm2 for 13A.
What think the assembled multitudes?

How about stepping it up to 2,400V and then stepping it down at the far end?

I can think of a lot more ways of doing it as well . . .

Bill


You may need this then Bill, I believe that they have a couple, one for
each end. Assuming of course that one could be used in reverse.

http://www2.ppauctions.com/lot.php?l_id=70116&id=138
--
Bill
( A different one )

On Friday, April 3, 2015 at 7:09:56 PM UTC+1, Adrian wrote:

Just talking to my next door neighbour. He's currently got a very long
extension cable strung across the road, on top of the tarmac, between his
house and his lambing shed. Call it 100m to be on the safe side.

He's going to run armour cable through the gulley under the lane, but is
wondering what size. Reckons he'll chuck a 20A RCD on the house end -
it's not much more than a bunch of light bulbs and the odd heat lamp, but
it'd be nice to have a socket there he didn't have to worry about using.

He was thinking 4mm2, but wondering if 6mm2 would be wise.
I found a cable calculator on t'web, and it reckoned 10mm2 for 16A or
above, 6mm2 for 13A.

What think the assembled multitudes?

Time to get creative: what if you used a transformer at the head end to add half the cable Vdrop, thus permitting half the xsa of cable lol. Or maybe you could run both conductors in parallel and use a ground return

A bit more seriously, wouldn't such a setup fall outside of the 17th edition regs? If so, while tungsten lamp light output is affected a good bit by Vdrops, CFLs, linear fl and heatlamps dont care.

Actually it might really be cheaper to use transformers at both ends, transmit at the cable's voltage rating limit.


NT

On Friday, April 3, 2015 at 9:34:00 PM UTC+1, wrote:
On Friday, April 3, 2015 at 7:09:56 PM UTC+1, Adrian wrote:

Just talking to my next door neighbour. He's currently got a very long
extension cable strung across the road, on top of the tarmac, between his
house and his lambing shed. Call it 100m to be on the safe side.

He's going to run armour cable through the gulley under the lane, but is
wondering what size. Reckons he'll chuck a 20A RCD on the house end -
it's not much more than a bunch of light bulbs and the odd heat lamp, but
it'd be nice to have a socket there he didn't have to worry about using.

He was thinking 4mm2, but wondering if 6mm2 would be wise.
I found a cable calculator on t'web, and it reckoned 10mm2 for 16A or
above, 6mm2 for 13A.

What think the assembled multitudes?

Time to get creative: what if you used a transformer at the head end to add half the cable Vdrop, thus permitting half the xsa of cable lol. Or maybe you could run both conductors in parallel and use a ground return

A bit more seriously, wouldn't such a setup fall outside of the 17th edition regs? If so, while tungsten lamp light output is affected a good bit by Vdrops, CFLs, linear fl and heatlamps dont care.

Actually it might really be cheaper to use transformers at both ends, transmit at the cable's voltage rating limit.

Go with Bill's 2.4kV and you could probably use tv aerial wire


NT

On Friday, April 3, 2015 at 10:12:27 PM UTC+1, wrote:
On Friday, April 3, 2015 at 9:34:00 PM UTC+1, wrote:
On Friday, April 3, 2015 at 7:09:56 PM UTC+1, Adrian wrote:

Just talking to my next door neighbour. He's currently got a very long
extension cable strung across the road, on top of the tarmac, between his
house and his lambing shed. Call it 100m to be on the safe side.

He's going to run armour cable through the gulley under the lane, but is
wondering what size. Reckons he'll chuck a 20A RCD on the house end -
it's not much more than a bunch of light bulbs and the odd heat lamp, but
it'd be nice to have a socket there he didn't have to worry about using.

He was thinking 4mm2, but wondering if 6mm2 would be wise.
I found a cable calculator on t'web, and it reckoned 10mm2 for 16A or
above, 6mm2 for 13A.

What think the assembled multitudes?

Time to get creative: what if you used a transformer at the head end to add half the cable Vdrop, thus permitting half the xsa of cable lol. Or maybe you could run both conductors in parallel and use a ground return

A bit more seriously, wouldn't such a setup fall outside of the 17th edition regs? If so, while tungsten lamp light output is affected a good bit by Vdrops, CFLs, linear fl and heatlamps dont care.

Actually it might really be cheaper to use transformers at both ends, transmit at the cable's voltage rating limit.

Go with Bill's 2.4kV and you could probably use tv aerial wire

Back to a bit more seriousness, could one use 2.5mm^2 with a tap changer at one end?

Re disconnect times, the head end mcb can protect the cable, then a shed end CU can protect the sockets, lights etc with quick disconnect times.


NT

On 03/04/15 22:17, wrote:

Re disconnect times, the head end mcb can protect the cable, then a shed end CU can protect the sockets, lights etc with quick disconnect times.


Quite a valid proposal as disconnect times on distribution circuits are
rather longer than end circuits (5s vs 0.4s)

On 03/04/2015 23:51, Tim Watts wrote:
On 03/04/15 22:17, wrote:

Re disconnect times, the head end mcb can protect the cable, then a
shed end CU can protect the sockets, lights etc with quick disconnect
times.


Quite a valid proposal as disconnect times on distribution circuits are
rather longer than end circuits (5s vs 0.4s)

Not that significant in this case alas where voltage drop is the driver.

Personally I would be happy designed to a 16th edition spec in this case
and allowing 4% drop on the submain - that would let you squeeze in with
10mm2 cable.


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

On Friday, 3 April 2015 19:09:56 UTC+1, Adrian wrote:
He was thinking 4mm2, but wondering if 6mm2 would be wise.
I found a cable calculator on t'web, and it reckoned 10mm2 for 16A or
above, 6mm2 for 13A.

If you use XPLE with a 90degC conductor temperature, and set ambient temp to 15degC for underground, non-lighting circuit, 3kW load, TLC calculator says 6mm is okay.

I'd be interested to see what MICC could do with an even higher conductor temp.

If he can get a few posts up then bare wire on insulators might be possible.

Owain

On 03/04/15 22:08, wrote:
On Friday, 3 April 2015 19:09:56 UTC+1, Adrian wrote:
He was thinking 4mm2, but wondering if 6mm2 would be wise.
I found a cable calculator on t'web, and it reckoned 10mm2 for 16A or
above, 6mm2 for 13A.

If you use XPLE with a 90degC conductor temperature, and set ambient temp to 15degC for underground, non-lighting circuit, 3kW load, TLC calculator says 6mm is okay.

I'd be interested to see what MICC could do with an even higher conductor temp.

It would make no difference -

The limiting factors are volt drop and lop resistance.

It's one of those cases where the absolute ability of the cable to carry
current without damaging itself is actually not the primary variable.

Thicker the better methinks.
after all you don't want it to be under road heating as well...
Brian

--
From the Sofa of Brian Gaff Reply address is active
"Adrian" wrote in message
...
Just talking to my next door neighbour. He's currently got a very long
extension cable strung across the road, on top of the tarmac, between his
house and his lambing shed. Call it 100m to be on the safe side.

He's going to run armour cable through the gulley under the lane, but is
wondering what size. Reckons he'll chuck a 20A RCD on the house end -
it's not much more than a bunch of light bulbs and the odd heat lamp, but
it'd be nice to have a socket there he didn't have to worry about using.

He was thinking 4mm2, but wondering if 6mm2 would be wise.
I found a cable calculator on t'web, and it reckoned 10mm2 for 16A or
above, 6mm2 for 13A.

What think the assembled multitudes?

On Fri, 03 Apr 2015 23:26:00 +0100, Brian Gaff wrote:

Thicker the better methinks.
after all you don't want it to be under road heating as well...

chuckle

Thanks, everybody. 10mm2 it looks like it'll be.

16mm2* sounds like it might even struggle to fit through the gulley he
was planning on using to take it under the tarmac...

* I typed 16m2 initially - that'd DEFINITELY be overkill...

"Adrian" wrote in message
...
On Fri, 03 Apr 2015 23:26:00 +0100, Brian Gaff wrote:

Thicker the better methinks.
after all you don't want it to be under road heating as well...

chuckle

Thanks, everybody. 10mm2 it looks like it'll be.

16mm2* sounds like it might even struggle to fit through the gulley he
was planning on using to take it under the tarmac...

* I typed 16m2 initially - that'd DEFINITELY be overkill...

Interesting thread. The expected load is not mentioned but also there seems
to be no thought for either future expansion or unforeseen temporary loads.
For example he might need a load of hot water and switch on two electric
kettles.
Just my 2d worth but if it were me I would definitely go for 16mm.
Does he have a 3 ph supply?
Nick.

On Saturday, April 4, 2015 at 3:54:13 PM UTC+1, Nick wrote:
"Adrian" wrote in message
...
On Fri, 03 Apr 2015 23:26:00 +0100, Brian Gaff wrote:

Thicker the better methinks.
after all you don't want it to be under road heating as well...

chuckle

Thanks, everybody. 10mm2 it looks like it'll be.

16mm2* sounds like it might even struggle to fit through the gulley he
was planning on using to take it under the tarmac...

* I typed 16m2 initially - that'd DEFINITELY be overkill...

Interesting thread. The expected load is not mentioned but also there seems
to be no thought for either future expansion or unforeseen temporary loads.
For example he might need a load of hot water and switch on two electric
kettles.
Just my 2d worth but if it were me I would definitely go for 16mm.
Does he have a 3 ph supply?
Nick.

On the contrary, the huge cable size makes it suitable for a larger temporary load. None of the loads mentioned are very Vdrop sensitive. Uprating the cable isn't cheap.


NT

On Sat, 04 Apr 2015 15:53:57 +0100, Nick wrote:

Interesting thread. The expected load is not mentioned but also there
seems to be no thought for either future expansion or unforeseen
temporary loads.

True. But if there's a 20A MCD at t'other end...

For example he might need a load of hot water and switch on two electric
kettles.

He'd probably just jog across the road to the house.

Does he have a 3 ph supply?

Definitely not. I know this because the single phase transformer is sat
up a pole behind my garage.

"Adrian" wrote in message
...
Just talking to my next door neighbour. He's currently got a very long
extension cable strung across the road, on top of the tarmac, between his
house and his lambing shed. Call it 100m to be on the safe side.

He's going to run armour cable through the gulley under the lane, but is
wondering what size. Reckons he'll chuck a 20A RCD on the house end -
it's not much more than a bunch of light bulbs and the odd heat lamp, but
it'd be nice to have a socket there he didn't have to worry about using.

He was thinking 4mm2, but wondering if 6mm2 would be wise.
I found a cable calculator on t'web, and it reckoned 10mm2 for 16A or
above, 6mm2 for 13A.

What think the assembled multitudes?

Further to other replies.
If it's a public "lane", he's not allowed to do it anyway.
Even if it's private and others have the right to use it there could be
legal problems.

He would have to get a wayleave.