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Posted By Topic: Transportable buildings been made perm...

Aug 22 2019 16:08

I have four transportable cabins on a site run on solar that are now staying...

the buildings are fitted with caravan plugs and have a single 20amp MCB inside for power points and lighting.

I am going to have to "hard wire" them in soon to the solar system as at peasant they are powered by 10amp leads (standard exten leads)run out to each building, this was going to be for 3 months but now will be perm.

Thinking is to run out either 3 core TPS in conduit or 3 core SWA or N/screen (all single phase) and fit entry boxes to the building in place of the sockets that are there.
Not sure what to do about the single MCB inside, guess I will have to remove them and hope there's enough cable in the walls (which I doubt) to fit a main switch and light and power MCB, if they run out feeds to each and not just one for all.....

Then wire a MEN switch board in the building with the solar bank.
Each building is appox 12 mtrs from the solar system.
I’ll put down an earth at each building as it’s in sand county and impedance is crap.

anyone have any other thoughts???


Aug 22 2019 16:58

Your existing set-up is non-compliant and unsafe.

only advice I can provide is hire an electrician; as what you are planing is beyond what the "homeowner" exemption covers

Aug 22 2019 17:07

i am the sparky

Aug 22 2019 17:17

There isn't enough information about the solar supply to comment much about that.

But yes you should run a submain to each building as normal. Replace the single MCB with a switchboard - main switch, RCD or RCBO etc.

I would recommend having an earth with the submain, and dealing with the main earth for the whole of the installation at the main switchboard.


Aug 26 2019 10:06

Thanks Doug that was my thought as well.

the solar system is a mess so going to re do the whole thing. i'll put the rcd's get at that the main board in the building that holds the batteries etc as there's really no where else for it.
as at the moment there are three rcd's fitted to each building..... one at board, one at entry point and one inside on the socket... with just one mcb...
love fitting other peoples job...

Aug 26 2019 21:29

As Alec has said the existing set up is not compliant and could never have been , so you have a chance to fix that up now that you are going to be making them permanent connections.
You said you are Going to put RCDs at the main board ! well you could do that but You would still have to install RCD's or RCBO's in each cabin there is no way round that.
Each cabin will need a sub board with main switch and the appropriate circuit protection for the circuits in the cabin