Massive run!!

[jam2020]

Hi guys,

im in doing a rewire in an old listed building sitting on 7 acres of land. About 190 meters away at the end of the garden they are going to put a temple type of pavilion so the daughter can get married there next year. Now of course they've decided they want lighting there. They're happy to dig the trench etc but I've never done anything with a run that big before. To get a 6a supply down there would require 10 mm swa. Is there anything anyone can think of I would need to bear in mind? Or any other suggestions to get over this? They've ruled out a generator or solar..


Thanks

 

[ruston]

Solar panels and a generator are a no no, the client wants a permanent supply down there, I would recommend to the customer a new 50 amp supply down there. A 4 way metal clad distribution board fed with armoured cable and terminated properly in the board, have 2 double sockets for the Disco man to plug his system into :biggrin: and a light inside the building with a security light on the outside, then 2 spare ways for future expansion.

The cable size would have to be determined, but as suggested earlier by another here a 3 core 25mm2 cable would be suffice, 16 may do it, may not, need to calculate it, if the house holder is loaded as suggested then he wouldn't mind forking out 3-4 grand for this I suspect, do it once= do it right.

Lol mentioning solar panels was tongue in cheek too. I agree with you It is to costly an exercise to skimp on a decent supply cable with all the implications that go with it.

 

[Guest77]

Lol mentioning solar panels was tongue in cheek too. I agree with you It is to costly an exercise to skimp on a decent supply cable with all the implications that go with it.

Lol I know you were kidding, the supply could be as small as 30 amp to be honest, however he may want a big shed down there one day so the bigger the better haha

 

[ruston]

That's me lol , belt and braces, no comebacks. It would grieve me having to do it again even if I was getting paid well.

 

[Guest77]

I have just calculated the cable size based on a 30 amp supply and a 50 amp supply at 200 mtrs buried, I was suprised by the latter result, lets see of the OP works it out as well, he may be suprised.

 

[Octopus]

All he will need now is an IP rated CU/enclosure so he can bury the box in the garden!

 

[Guest77]

HAHA that old chestnut again

 

[ruston]

Lol , I see what you mean. Mind I cheated.irate:

 

[davesparks]

With my production/event electricians hat on I can honestly say I think the generator hire option is better.

If these people have got that kind of money to waste I would expect, from experience, that the wedding will be very big and expensive.

And every wedding which happens in that kind of venue will be different and have their own needs. There will no doubt be a band put in there to play at some point and you'll want some decent amount of power for that.


Plus we all dread working at venues where 'power has been installed by our electrician', it is almost never big enough or suitably installed.

There is a venue locally where I put up lighting for an event last year, they had installed 1x20A radial to 13A sockets at high level for lighting in this average sized barn.
1- we need it at low level to feed the dimmers which we then take cables to high level from.
2- after the 1KW of chandelier had gone in that left me 3.8KW to feed 8KW of overhead lighting.
I ended up putting in a temp 32A and 16A supply as we almost always have to do, and always carry the kit to do so with.

We have also got in to the habit of asking our generator suppliers to have one on standby if we are working at a venue where 'our electrician has installed a big socket' as it is usually only a 32A single phase socket, far too small!

 

[Marvo]

I've been told lights. I'm not going to put anything other than 6 amps down there

Exactly what I'd do. Get it in writing that they require only 6A for lighting then install your 10mm SWA.

When they come back to you a week before the wedding with a larger requirement.....and they will come back, then you quote for a pair of asymetrical transformers. Install a 230v-980v step up transformer for the supply side and a 935v-230v step down for the marquee side, that way you can upgrade the circuit capacity and compensate for volt drop all in one nice easy package

 

[Guest111]

I wonder how the OP would go on if it was a big run?


People just don’t look in the manufacturer’s specification for minor things like cable weight.
Another member of the forum was with me when we had a young guy confidently tell us that he’d supervise his two lads pulling a cable in and getting it on to the traywork. Only a mere 1¼Ton each, they’ll manage that in a couple of hours.
We legged it, never to return.

Aye but lets not forget his plan A,something about a wooden roof and several tonnes of cable.

 

[Knobhead]

Exactly what I'd do. Get it in writing that they require only 6A for lighting then install your 10mm SWA.

When they come back to you a week before the wedding with a larger requirement.....and they will come back, then you quote for a pair of asymetrical transformers. Install a 230v-980v step up transformer for the supply side and a 935v-230v step down for the marquee side, that way you can upgrade the circuit capacity and compensate for volt drop all in one nice easy package

Oi you! I was waiting to step in with that! It's OK so long as the cable is 600/1000V grade, 300/600V and your f****d.

This is one I came up with for another member of the forum a while ago.

Yes. We were in silly mode at the time.

 

[davesparks]

Just hire a sodding diesel generator!

It's someone else's problem to do the maintainence then too!

 

[Marvo]

Yeah.....that's kinda what I was suggesting

It was a serious suggestion and you're right, it would swing on the SWA cable being the type rated to 1000v. It's a system we've actually used before for long runs and at the time it worked out considerably cheaper than installing the 2 kilometers of cable at the size required for 230v. I can't vouch it would pass muster under the UK regs but it scraped through under our local regs (only by about 4v during off-peak times mind you).

 

[Knobhead]

Aye but lets not forget his plan A,something about a wooden roof and several tonnes of cable.

That would have been funny!

 

[Knobhead]

Just reread this thread.

Yeah.....that's kinda what I was suggesting

It was a serious suggestion and you're right, it would swing on the SWA cable being the type rated to 1000v. It's a system we've actually used before for long runs and at the time it worked out considerably cheaper than installing the 2 kilometers of cable at the size required for 230v. I can't vouch it would pass muster under the UK regs but it scraped through under our local regs (only by about 4v during off-peak times mind you).

What was the loading and what size cable?