XFMR Help.

Thread Starter

pinkblob66

Joined Nov 17, 2014
4
Hello, new to the forum here. Need some help and direction as far as power stuff...

I'm trying to design a box which will probably be wall mounted that takes a main line of power. There is a 100A 120VAC XFMR that creates an output of 50A 230VAC. I need to take that 50A 230VAC line and create three 15A lines. Is this just as simple as taking the main line, going into a wall mounted box and feeding that line to a bus bar within the box, then from the bus bar attach three 15A circuit breakers, which ultimately feeds three 15A lines out the other side of the box? I'm relatively new to the electrical world, so any input would be appreciated. I'm just trying to learn as much as possible :)
 

MaxHeadRoom

Joined Jul 18, 2013
28,619
You will have to assign one side of the secondary(ies) as a neutral and bond this right at the transformer to the existing Service Earth ground point.
From then, at no other point should the neutral contact earth ground, also do not place a fuse in the neutral conductor.
Max.
 
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Thread Starter

pinkblob66

Joined Nov 17, 2014
4
I understand that I'm new and should get help from a licensed electrician, but I do know the core concepts. Right now I'm just designing on paper, which means I'm not going to die if I touch a pencil line to a pencil line haha...

With that being said, I have drawn up a little schematic of what I'm trying to explain. E1 is an earth ground.
 

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MaxHeadRoom

Joined Jul 18, 2013
28,619
If this is an isolated (Transformer) supply then the N point on the transformer and your ground plate has to have a correct sized earth ground conductor to be connected to the service earth ground that is usually provided at the service entrance.
What country are you in?
Max.
 

Thread Starter

pinkblob66

Joined Nov 17, 2014
4
Earth ground is connected to bus bar W2 and will be connected directly out of said box to Earth ground at the building. I do not show any of the connections from the building to transformer. The transformer I'm going to use will have L, N, G going in from building supplying 120V
 

MaxHeadRoom

Joined Jul 18, 2013
28,619
If the supply you show is from a 240v secondary of a transformer, have you determined whether or not the secondary is in fact connected to earth ground?
IOW a proper neutral set up?.
Max.
 
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