Temporary supply to portacabins

[Paul228]

I have three portacabins arriving on site.
Each cabin is pre-wired and has a 32A plug connected to the consumer unit.
They are 80m from the site distribution board.
I need some suggestions on the best and cheapest way to feed these.
The option I've come up with is run 3 lengths of 3 core swa and simply put a 32a connector on the end of each. This would involve me running 3 lots of 6mm cable and placing a 32a rcbo for each circuit at the dis board.
I was also considering running a single cable to the first portacabin and then distributing to each of the CU from here, but the cable would need to be 25mm swa, given I need about 30a at each cabin ( not continuously).

 

[telectrix]

how many circuits in each cabin? and what's the fabric of the cabin. wood or steel?

 

[LankyWill]

The cu inside the cabins are usually protected by an rcd anyway. What's the earthing arrangement? Is it a 3 phase supply?

 

[Paul228]

The cabins are wooden, two circuits in each.
6A lighting in each and a 32A ring in each.
All 230v.
Cabin one is a changing and drying room with a 3kva heater . Cabin 2 is welfare, a couple of 13a sockets for a kettle and radio.
Cabin 3, is the site office, usual heater and lap tops

 

[Paul228]

It's single phase required at the site cabins.
The distribution point at the factory has 3phase, 230v and 110v.

 

[telectrix]

why not run out a 3 phase cable, split at first cabin 1 phase for each. and with only 2 circuits per cabin, division of circuits does not apply, so a RCD main switch in each CU would be cheaper than RCBOs. i should think this is already in situ, using a standard 2 circuit "garage board".

 

[Paul228]

I was thinking doing this, but it would mean splitting the phases down in an IP44 board outside the cabins, as we can not drill into the cabins as part of the hire agreement.
I'd probably need to run a 5 core 10mm swa from the distribution point and the mount a board on the adjacent wall. Then break each phase from here.
Do you have a board you would recommend. I've used giwiss in the past, but these can work out expensive for a project only lasting 6 months

 

[LankyWill]

Materials cost what they cost, you can't do a rubbish job because it costs money to do it properly. I'm almost certain the board inside the cabins will have rcd protection on them. I wouldn't bother putting rcd protection on the supply armoureds.

Either run each supply separately using the correctly sized swa probably 6mm from the dis board

Or use Tels idea of running a 3 phase cable and teeing of per each cabin. Mount a gewiss on top of the cabin and secure with zip ties through the tie eyes on the cabin.

Or run a supply to an external meter box nearer the cabins using a larger cable and distribute From there.

 

[Paul228]

Cheers lankywill.
I never had any intention of doing a "rubbish" job. I wanted to do the most cost affective.
There is more than one way to skin a cat. I just wanted the cheapest way to do it safely, given its only for 6 months.

 

[LankyWill]

I'm not trying to come across offensive mate, I know what it's like when the boss wants everything done for squat. That said the cheapest is probably 3 separate armoureds by the time you add all the gewiss boxes and glands. I'd get some cable quotes and go from there, eddies usually do armoured pretty cheap

 

[Paul228]

No offence taken .
You are correct, the boss wants it cheap as chips. I jokingly said a choch block, poly bag and insulation tape would do it. He thought I was being serious.
Cost wise...3 separate cables, but it will take me longer banging in 300+ cleats.
Nite all.
Glad I joined the forum, been reading it for a few years now.
You all seem a friendly bunch of sarky sparkles.

 

[Dozer 73]

how many circuits in each cabin? and what's the fabric of the cabin. wood or steel?

Cabin usually steel , circuit no's 1* LGt 1* ring 2* htg or air con
Majority of power used is heating or cooling 4 kw max , power usually very minimal , couple of pc's and phone chargers
Offices don't take much load it's the canteens , drying rooms and toilets you have to consider loads more

 

[Bbsimon]

80m? 6mm Check ya cable calcs

 

[Toneyz]

Probably wired it by now.