Is there anything in the code that prohibits using a 120/240V residential type generator where the electrical system is 120/208V-3PH-4W? Normal feeder would be 120/208V-1PH, and generator load would be 120/240 1PH. Transfer switch would be 208-600V rated. Panelboard voltage would switch between 208 and 240, can nameplate be 120/240-1PH-3W. Of course, we'd have to check ratings of connected loads, but most would be 120V receptacle circuits. should neutral be switched to make generator a separately derived system?
Residential Generator on 120/208V system
- Thread starter DW98
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IF you have 208 volt equipment, from a Code standpoint you will be violation of 110.4
From a practical standpoint, I think it would depend on the specific equipment.
As to the SDS, if the transfer switch switches the neutral, the generator would be considered a SDS.
From a practical standpoint, I think it would depend on the specific equipment.
As to the SDS, if the transfer switch switches the neutral, the generator would be considered a SDS.
iceworm
Curmudgeon still using printed IEEE Color Books
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There are likely code issues, I didn't look - and augie probably knows better than I do. However, I do see some design issues.
Assumption: the utility service is three phases and a neutral (208/120 3ph, 4W)
What wire from the generator are you going to connect to the third phase of the panel board? If you are planning on just leaving one panelboard phase un-powered when under generation, what is your plan for back-feed through 208V single phase loads or 208V three phase loads to the un-powered phase?
If I had to do this, I'd be looking at installing a 120/240 single panel for critical loads and just feeding it with 2 phases and a neutral from the utility.
For the SDS part, you would need a 3 pole transfer switch.
ice
hillbilly1
Senior Member
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- North Georgia mountains
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Thats what most people do, install a two pole breaker in the three phase panel to feed the transfer switch, in turn feeding a single phase panel. Most of the ones I've done had only 120 volt loads, so the 208/240 volt output is not a problem. A lot of 208 volt single phase equipment is also rated for 240 volts also, the OP just needs to verify.
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