Conductor transition to lower Voltage Drop

[stuartdmc]

The missing equation is the VD at the meter section. I have to start at the 4000-amp mains, from the main we run 100ft to the meter sections, In stead of starting at 0% VD, we're starting at 1.2 to 1.8% VD as worst, that means we only have 2.4% to go 600ft. to the panel, then after we reach the panel, I must allow at least 1% for the branch circuits worst case. and I don't think 1% is even good enough, the worst case branch circuit is the run to the RTU, and that can be as faraway as 100ft. plus feet.

 

[LarryFine]

I keep thinking, "What's wrong with good ol' SER?"

 

[oldsparky52]

Using the full panel/feeder rating for the current is probably not even necessary. FYI I get 4% with your parameters. OP beware of some online calculators like the southwire one, they use 90% PF (which is very likely un-necessary as large resi loads will usually be resistive). That one gives 5% with the above parameters.

Dang, caught me using the 1st on line VD calculator w/out checking. Using the VD formula MH has and then using VD=IR, I come up with a VD of 7.42 volts which is about 3.6%.

I agree with your comment about the load. Thanks for the catch.

 

[oldsparky52]

The missing equation is the VD at the meter section. I have to start at the 4000-amp mains, from the main we run 100ft to the meter sections, In stead of starting at 0% VD, we're starting at 1.2 to 1.8% VD as worst, that means we only have 2.4% to go 600ft. to the panel, then after we reach the panel, I must allow at least 1% for the branch circuits worst case. and I don't think 1% is even good enough, the worst case branch circuit is the run to the RTU, and that can be as faraway as 100ft. plus feet.

Sounds like a mess.