Residential Electrical Service

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Brian C

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Massachusetts
Hi All,
I have a voltage drop question on a 200 amp- 200' underground service. 120/240 single phase.

When I do the calculation should I plug in 120v or 240v in the equation?
Thanks/Brian.
 
Brian C said:
Hi All,
I have a voltage drop question on a 200 amp- 200' underground service. 120/240 single phase.

When I do the calculation should I plug in 120v or 240v in the equation?
Thanks/Brian.
Click to expand...

240
 
240 but you want to try to keep load balanced so neutral is carrying as little current as possible otherwise you will be looking at drop on 120 volts if you have one leg heavily loaded and the other is not.
 
As the others have said, 240 as it can be expected to be reasonably well balanced most of the time. But I would for sure use a full size neutral for help in periods when it is not as well balanced.
 
Actual incoming utility voltage comes into play here too. I've got a 250 foot run from the POCO handhole to my service, and I didn't worry about voltage drop because they had 243 volts L-L at the handhole. Had it been a much longer run, I would've broken out the calculator. :cool:
 
texie said:
As the others have said, 240 as it can be expected to be reasonably well balanced most of the time. But I would for sure use a full size neutral for help in periods when it is not as well balanced.
Click to expand...

ActionDave said:
Considering in an average 2500 sq ft home that the most you would draw is neighborhood of 60 to 80 Amps, unless you have electric heat, voltage drop for 200' is not much of a concern.
Click to expand...

And if it is electric heat (likely 240 volts) that is that much less neutral load and good enough reason to reduce neutral size - you can't load the neutral it if it is not a line to neutral load.

If you have a 25kW 240V heating system you have about 105 amps of load that will never be on the neutral why should the neutral need be sized same as ungrounded conductors?
 
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