small building site temp distribution

[Eric M]

I am setting up some temps on a small site consisting of approx 3 110 transformers 2 portacabins offices sitting on top of each other, a portacabin toilet and a portacabin drying room.
The supply is a 3 phase DB.
Im thinking use 1 phase for the trannys, 1 phase for the offices and the other phase for the loos/drying room.
My colleague says we should use just 1 phase for the toilets/drying room/offices because of the potential 400v across the phases however that would leave one phase unused and a very unbalanced load.
Any advice welcome.
cheers

 

[Deleted member 26818]

My advice would be to do, as you suggest.
Yes there will be 400V between phases, so what? That's the nature of 3phase.

 

[Leesparkykent]

My advice would be to do, as you suggest.
Yes there will be 400V between phases, so what? That's the nature of 3phase.

Plus 1

 

[Brightspark2]

Plus 2

 

[davesparks]

Balance the load, one tx on each phase, and spread the port acacias across the three phases

 

[telectrix]

acacias on a site.??? next they'll want daffodils and tulips. :juggle2:

 

[Eric M]

would it not be better practice to keep all the transformers on the same phase? Although the outputs are 110v if they are on different phases couldnt that make the potentials across the 110 outputs higher between transformers? or am I overthinking this?

 

[Eric M]

Balance the load, one tx on each phase, and spread the port acacias across the three phases

Would it not be better practice to keep all the transformers on the same phase? If they are on different phases wouldnt it mean the 110v outputs would be at different phases and therefore you could come in to contact with more than 110v? or am i overthinking this?

 

[Risteard]

You could always use three-phase 110V RLV transformers to help keep the phases balanced.

 

[Eric M]

You could always use three-phase 110V RLV transformers to help keep the phases balanced.

I think the main contractor is supplying the transformers. I know im not!

 

[davesparks]

Would it not be better practice to keep all the transformers on the same phase? If they are on different phases wouldnt it mean the 110v outputs would be at different phases and therefore you could come in to contact with more than 110v? or am i overthinking this?

I think you are under thinking here, maybe brush up on transformer theory and the basics of electrical safety.
The whole point of 110V CTE is to reduce the voltage to earth to 55V should someone make contact with one of the line conductors. The three transformer outputs will only ever be 55V to earth whatever phase they are fed from.

 

[Eric M]

I think you're right, its been years since I looked at transformer theory. Cheers for advice.

 

[Eric M]

I think you're right, its been years since I looked at transformer theory.
I understand the max voltage to earth being 50v because of the centre tap however what about the max line to line voltage on the 110v outputs? Presumably this isnt an issue otherwise 3phase transformers wouldnt be in use.
Cheers for advice.

 

[davesparks]

I think you're right, its been years since I looked at transformer theory.
I understand the max voltage to earth being 50v because of the centre tap however what about the max line to line voltage on the 110v outputs? Presumably this isnt an issue otherwise 3phase transformers wouldnt be in use.
Cheers for advice.

What about it? What fault are you envisioning that has someone coming in to contact with the line conductors from two different transformers?

 

[Eric M]

What about it? What fault are you envisioning that has someone coming in to contact with the line conductors from two different transformers?

I guess its unlikely and Im just thinking hypothetically, site temp distribution isnt something that ive had to deal with before.