We are in a rural area but are hearing from most all equipment manufacturers we speak with that seeing utilities deliver higher and higher voltages in an attempt to avoid upgrading old, undersized, lines is pretty much the norm now. In our area and in speaking with electrical inspectors it seems to be the case in our entire region, its not uncommon to see 130-134 volts per leg (260-265). Our shop is located right on the main road in town and there are several rural roads running out miles and our shop frequently see's 262-264 volts. We have taken issue with the power company and they have installed recording meters and told us that they are allowed 10% which means on a 240v service they can hit as much as 264 volts and still be in spec..
Well, our shop was dead at 262 for the longest time (I installed a digital meter beside the panel). We have now installed a CNC which we are told has Mitsubishi controllers that dont want to see anything more than 238. So we have installed a buck an boost (single phase) to buck the voltage down to 238. It has always been my understanding that unbalanced legs on a single phase system are not a problem. The buck and boost drops L2 to 106 and leaves L1 at 132.
Low and behold today I look at the meter and its reading 263.9 volts. A tenth of a volt below their allowable limit.
I will be taking this up with the PSC as we go through light bulbs, and fluorescent ballasts like toilet paper but wondering if anyone knows for sure about the unbalanced legs on a single phase system.
Thanks
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