[BC] AC Voltage Drop

[Chris Gebhardt]

Danny Ray Boyer wrote:
> To the NEC guru's on the list -
> 
> Can anyone direct me to the paragraph(s) in the NEC handbook which 
> reflects what kind of voltage drop is permissible from an electrical 
> provider from no load to full load.  This is for a a 240 volt - 3 phase 
> Open Delta AC circuit. 
> 
> The power transformers on the pole are within 150 feet of the load.  The 
> 3 conductor wire (and neutral) between the ransformers on the pole and 
> the fused disconnect panel are sized for 200 amp. 

IIRC this can vary from provider to provider.   Call your local utility 
and and ask them.  You'll probably need to play phone tag a bit since 
you'll need to get with engineering.

We had a very similar situation to yours with the 240 Delta and 
transformers within 150 feet (which the utility engineer felt was a 
little far away).  After placing a recording meter on the line for a 
week, they agreed that what we were seeing was not within tolerance. 
They planted a new pole & 3x new transformers.  (We moved to 208 3phase).

One thing the engineer who led our project mentioned was that there 
isn't a lot of demand for 240 Delta these days, and the equipment in use 
for such supplies is typically quite a bit older and not as well 
maintained.   Sort of "forgotten infrastructure" I guess.

Chris Gebhardt
VIRTBIZ Internet Services
chris at virtbiz.com | (972) 485-4125