3Phase Mobile Van Work Shop

[Ben Bygrave]

I have been Asked to kit out a transit with a 63a 3phase supply, 32a 3phase supply both on 5 pin commando sockets.

I was just going to put a 4 way 3phase consumer unit inside with these circuits in no problem. but what size cable should i be running from the generator. these are both going to be used at the same time so i was thinking 125a floating socket and fix plug on  the van with 25mm h07 cable  is this over kill if I'm only running 3m from the gen?

 

[ProDave]

I would want to see the generator that he's going to be using.  What you are describing is an 85 KVA generator.  That will be on a big trailer then?  

You can get small 3 phase boards that look like single phase CU's for just a couple of circuits, a lot cheaper and smaller than a "proper" 3 phase board.

 

[SLIPSHOD & SLAPDASH]

I dont think those figures are correct. Perhaps someone has added the max loadings for every piece of equipment together ?

I also dont like the idea of a normal board in a vehicle. The terminals It would need checking for tightness  very regularly.

 

[ProDave]

No different to a caravan (or motorhome). You would normally wire in flex for that reason. I would treat it as a 3 phase caravan install and apply all the rules for a caravan installation.

 

[Andy™]

why use caravan section when there is a section for mobile or transportable units (which includes vehicles)

 

[ProDave]

why use caravan section when there is a section for mobile or transportable units (which includes vehicles)

Yes of course I forgot that.

I've never personally been asked to work on the electrics of such a vehicle so I've only ever glanced at that section of the book.

 

[Ben Bygrave]

 thanks guys! some one has told them they use a 44kva gen and run the same equipment. but i didn't want to just do that if it was underpowered. should i install to maximum loading ? 

 

[Andy™]

what do they do that needs so much power?

 

[apprentice87]

Hi Ben,

Whatever size cable you need for the load, is what you need!! makes no difference if it is 3 inches long or 3 miles. [Ok, the volt drop would!!!!]

How they earth the body of the van so that in case of a fault the whole thing does not become live??

john..

 

[Phoenix]

How they earth the body of the van so that in case of a fault the whole thing does not become live??

john..

Back to the star point of the generator, like any other TN-S system

Or if you mean how is the star point of the generator tied down to earth?.... very poorly most of the time and not likely to acheive the sub 21 ohms required. Seen them with a metal plate that one of the wheels is parked on... that sort of idea might be fine for a radio earth or similar but is rather poor at 50hz