Ok, been a bit thick and forgetful(books at home)
80m Run, single phase xple or pvc
load 11kW
ib 37.5A
In 45A
Iz about 80 for 16mm, 120 odd for 25mm?
Clipped on a wall
TT at load end in an outbuilding.
with voltdrop am I looking at 16mm xple or 25mm PVC. twin SWA?
Given the MET is from the earthrod at the outbuilding and the sheath isn't the main earth bond?
Haven't got my regs on me so can't look it up! Don't really trust online cable calcs....

Help!!

To keep within a 2% volt drop limit you need a 16mm2 x 2 core (XLPE/SWA run to 70C)

If you can live with about 2.7% a 10mm2 will be OK

I've assumed an RCBO or MCB and RCD for source end protection (Type B and 30mA) - not that it will influence the volt drop of course

Regards

OMS

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Failure is always an option

cheers oms, i'll err on the side of caution, there is a tea urn and lots of lighting on the end!

Well if you`d have stated a tea urn right at the start we`d gone for 35mm backed up with solar, wind and a genny to start with.
Essential services need special provisions against failure

-------------------------
Regards,
Ebee (M I S P N)

Knotted cables cause Lumpy Lektrik

they already have thayt in the shape of a 1.25mm.. 100m extension running from the house, this is the backup....

OK - I guess 2% is as good a number as any - that gives you a bit for final lighting circuits not exceeding 3% from origin - but it's all a bit arbitary. As I said, 10mm2 would do it fine, but as the labour is going to outweigh the cable cost, well, 16mm2 it is - that'll be two sugars in mine, then

regards

OMS

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Failure is always an option

Whats the need for a B or is everyone fitting B's to B on the safe side future proof etc

Well, in a hierarchy of risk a Type B is safer than a Type C or D as it needs less fault current to operate in the same time (helpful if our assumption that the fault is of negligible impedance proves not to be true)

I'm not sure what inrush loads you'd expect from a tea urn and a few lights in a shed exactly, but a Type B does it for me

Of course, if the client decides to take up commercial welding in the shed or installs a small x ray inspection machine we may need to rethink

Regards

OMS

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Failure is always an option

hmmm, welding may be an option on this one! Think a type C or A BS88-6 may be in order, Got a nice bigearth point to do the TT on, it used to be an old propane filling plant!
Just got to make sure the urn isn't on top of a filing cabinet next to a radiator.....

Ok sorry, I had me wires crossed. I thought you were suggesting a "type b rccb 30mA".

hmmm, welding may be an option on this one! Think a type C or A BS88-6 may be in order, Got a nice bigearth point to do the TT on, it used to be an old propane filling plant!
Just got to make sure the urn isn't on top of a filing cabinet next to a radiator.....

I'll take my chances, big red - just get a bloody brew on - I've a throat like an arabs sandal -

fuses will be fine - stick a REC 3 switchfuse and a 100mA S type at the supply end with 30ma and seperate local electrode at the load end

or use the system earthing arrangments for the sub main (Zs and CPC characteristics permitting) and gap the SWA at the load end with 30mA final circuit protection

Regards

OMS

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Failure is always an option

tea will have to wait if there is another xmas beers up!
was looking at the latter, the cable is pretty well protected, its pme at the board end, so will use a decent ip box at the load end and gap the swa. There is a chance that the outside supply is used when the building inside is not, not ideal, but its a chance that power could be lost at source and we can't reset.
Cheers
Dave

OK - as big a fuse as overload and Zs will allow source end - not sure how your "outside supply" is arranged but can you get an RCD into the plastic enclosure when you isolate the armouring - that way you get RCD protection on the outside supply and for the outbuilding

Or provide the outside supply from the outbuilding might be easier ?

regards

OMS

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Failure is always an option

the latter is teh plan, teh outbuilding is 80 meters away from the source, it's a polestar board there, so type B or C breaker. Given they will more than likely plug a welder in for sculpture making, more than likely type c
Since the outbuilding is only quite small, i'll use a RCD main sw, 16A sockets will be after the outbuilding RCD, legrand switch /socket isolater interlock. And then find a convienent girder stud as an earth rod.....:-)
cheers for the words of wisdom
D

OK - just be mindful of a fault on trailing leads dropping the lot out - I wouldn't want to be in the middle of being creative with a guillotine or folding bars when it all goes dark (unless you are planning emergency escape and high risk task lighting)



LoL - OK, it'll save a bit on the bonding - and I guess will double up as a workpiece earth as well

Personally, I'd go "split load" regardless of size of installation - more bucks I know but metalworking machinery (or a bloody pugmill) are not the best bits of kit to be mishandling in the dark that's for sure.

failing that a set of blocks and two front end DB's would do it - particularly if some kind soul has a couple of spares knocking about looking for a home - all in the philanthropic vein of course

best regards

OMS

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Failure is always an option

Funny enough oms, this is for an arts project! All my spare boards are metalclad,could always stick them in a plastic box!
think they can get some budget for the bits, labour? there goes my holiday again....
And yes, tht kind soul has facilitated quite a few things, wiring of a kiln, finishing off artists studios to name a couple. Many beers
owed!

Tell me about it - I once spent about 4 hours in my fishing waders standing in a "pond "setting precise aiming points for underwater luminaires to illuminate a bloody great piece of glass and bronze that represented an Autumn leaf half curled and floating on water.

I think the artist, who appeared to only have a first name and was very adept at commenting "left a bit, left a bit - stop" was starting to forget that my time, effort and the very expensive luminaires were being given free of charge to the project because they had run out of brass - I particularly remember it because I also ended up with the bill for Starbucks becaue her and her friends had got cold - and the cup of coffee they brought me back because I was sodding freezing at that point had no bloody sugar in it

Still, I guess you need to suffer for your art

regards

OMS

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Failure is always an option

Suffer? I wanted to install a lighting piece, but have been told the only way is to accomodate the shed which has the tea shop plus the little workshop. Well at least they will pay for the bits, 80m 16mm 2 core? sunday afternoon in the sun, better charge that dewalt.....
Suffer? i'm a masochist, and thats not even when i'm replying to DC...

Yet it seems that it's usually other people that suffer for their art ?!?
- Andy.