208v to 120v transformer wiring

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titan1021

titan1021

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Northern California
I am installing a 1.5kv multi-volt step down transformer with a primary voltage of 208v and going to a secondary of 120v. I need the 120v for a gfci to power landscape lights.

Do I need to ground of of the leads in the transformer to create the neutral ?

Thank you
 
I assume you mean 1.5 KVA... not sure why you need the transformer, 208 volts is usually from a Wye configuration with a neutral and you should have 120 volts l-n.
 
augie47 said:
typo perhaps ? 12 v ?
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it would have been the same typo twice.

my take was for some reason he already had the 208V single phase there and just wanted to get 120V out of it. That was the only thing that made sense to me from what he described. I do wish people would provide just a little more information on these type of questions rather than making us guess at some of the stuff.
 
Makes sense..sorry we questioned you... as mentioned 250.20(B)(1) and 250.30
 
A GFCI device depends on one conductor being grounded to function. Otherwise, there would be no current to earth to cause a shock.
 
LarryFine said:
A GFCI device depends on one conductor being grounded to function. Otherwise, there would be no current to earth to cause a shock.
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That's just plain not true. It will function on two hot's as well. It only looks for an imbalance in the current flow in the two wires.
 
petersonra said:
That's just plain not true. It will function on two hot's as well. It only looks for an imbalance in the current flow in the two wires.
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It'll function on 3 phase with no neutral or ground as well. You are correct that the device only looks for a current imbalance. Differences for a 120 or 208 / 240 device, you're looking at 20 to 50 bucks... for 3 phase, well, I'll let you enjoy the sticker shock of looking up what a QO330 GFI breaker costs.:lol:

I'm not sure at the moment what part of 250.30 would be 'fun'..... some other options would be to run a landscaping lighting at 208v, maybe install a 208 / 24 volt transformer for the lighting to bypass the receptacle requirement, or if possible change the parking lot lighting to 120 volts to bypass the need for a transformer.

I'm never lucky enough to find a commercial lighting circuit that isn't already 80%, or more, of the breaker it's on....

Where are you planning on mounting this xfmr?
 
petersonra said:
That's just plain not true. It will function on two hot's as well. It only looks for an imbalance in the current flow in the two wires.
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But, a person contacting one line and earth will not cause such an imbalance with no circuit conductor connected to earth.

Same thing as the first fault to ground on an ungrounded system not causing an over-current device to open the circuit.
 
Here I'm referring to the secondary circuit of the transformer proposed in this thread. An ungrounded circuit has no need for a GFCI device, as there is no electrocution risk except for line-to-line contact, against which a GFCI does not protect.
 
LarryFine said:
But, a person contacting one line and earth will not cause such an imbalance with no circuit conductor connected to earth.

Same thing as the first fault to ground on an ungrounded system not causing an over-current device to open the circuit.
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Absolutely correct, there isn't much for hazards until a second ground fault occurs either, First fault just turns it into a grounded system. GFCI will still respond should that second fault happen.

petersonra said:
The fun part might be finding an appropriate grounding electrode system out in the parking lot.
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Maybe. If you have a rod at pole you may still need to add another rod. Large pole base may not quite meet CEE requirements, but reality is may still have less earth resistance than two rods:blink:

titan1021 said:
I am installing a 1.5kv multi-volt step down transformer with a primary voltage of 208v and going to a secondary of 120v. I need the 120v for a gfci to power landscape lights.

Do I need to ground of of the leads in the transformer to create the neutral ?

Thank you
Click to expand...
You ground one lead to create a "grounded conductor"

A two wire secondary has no "neutral".
 
Is there any way to allow the secondary to remain ungrounded and omit a GFCI device completely? Perhaps install the transformer within the pole, so only the secondary is easily accessible?
 
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