I am giving a customer some different options on a project where his shopping center sign was never wired. I found the feeder conduit to be broken under the parking lot. It is a long way from the electric room to the sign, maybe 400-500'. There is a light pole 25' away from the sign, the lights are single phase 208 volts. Do they make a transformer I can put between the 2 to go from 208 down to 120 without having a neutral on the primary? Can the transformer produce a neutral from a ground?
A darn good question and have a very similar situation right now.
Here is what we found:
277v lighting feeding the lot poles. They then fed a single phase transformer to go from 277 to 120 for the sign. They bonded one side of the secondary to the grounding conductor to create the neutral but I did not like it so I have recommended that the ballasts for the sign be changed out to 277v and eliminate the transformer.
A darn good question and have a very similar situation right now.
Here is what we found:
277v lighting feeding the lot poles. They then fed a single phase transformer to go from 277 to 120 for the sign. They bonded one side of the secondary to the grounding conductor to create the neutral but I did not like it so I have recommended that the ballasts for the sign be changed out to 277v and eliminate the transformer.
they have correctly installed the transformer.XO must be bonded on a seperatly derived system the bond does not create the neutral.
I would just change the lamp ballasts to multi-tapped to match the voltage at the lamp location. If the feed was broken under the lot, I would use a tracer to locate the break and repair it.
208 to 120 transformer with no neutral
Posted - 02/06/2010 : 10:58:39
