Inspectors can't enforce voltage drop so... tell me what you think about this...

Status
Not open for further replies.
O

olly

Senior Member
Location
Berthoud, Colorado
Occupation
Master Electrician
I have a customer that has a shed / barn 320' away from the main on the pole. I am changing the main to a 200a 8 CRKT panel with feed through lugs on the bottom. The existing house is on a 100A. So I will put the house on a new 100 amp breaker in the new 200a 8 crkt panel. Here is where the question is. I was going to run 4/0 URD, land it on the feed through at the bottom of the main disconnect, run it 320' and mount another 200a 8 crkt panel on this shed. You and I both know they wont pull over 80a and we also know the wire should be upsized for this voltage drop but I am trying to keep conductor cost down along with labor of installing heavy 350 or something close. What do yall think? Technically this will be to code because 4/0 wire is large enough for a 200a.
 
ActionDave said:
Why are you running 200A wire to the shed?
Click to expand...

It is a small wood working shop and they will have small electric heat loads, so they probably need 100a. This option also saves me from buying a smaller breaker as I can just land them on feedthrough lugs. Also If I were to install say 100a breakers, panels I would have to get larger wire (for voltage drop) under a small breaker on both sides and I would still be installing 4/0
 
olly said:
I was going to use URD why do you say use conduit?
Click to expand...

PoCos are the biggest users of URD.
we haven’t direct buried any wire, including streetlight wire, in about 20 years.
Many are now putting URD in conduit or borepipe.
Those that don’t usually have a dedicated crew that does little more than go job to job repairing bad URD.
Duke service techs regularly tell me they fix an average of 4-5 a week.
 
olly said:
It is a small wood working shop and they will have small electric heat loads, so they probably need 100a. This option also saves me from buying a smaller breaker as I can just land them on feedthrough lugs. Also If I were to install say 100a breakers, panels I would have to get larger wire (for voltage drop) under a small breaker on both sides and I would still be installing 4/0
Click to expand...

Well that makes sense for work ability if you are going to use 4/0. I'd be real curious what the load is even with all the heat running and the place packed full of power tools. If you said anything above 45A I'd bet a hundred dollars and take the under.
 
Can one use larger wire for VD, and splice to "normal" wire in the panel before landing on the breaker? Same as running large wire to a remote receptacle and then using standard wire pigtails at the receptacle, right?
 
ptonsparky said:
I’m exaggerating the example. I don’t have a code book next to me but if you increase the size of the conductors to compensate for VD you must increase the EG as well. One of the idiosyncrasies of the NEC.
Click to expand...

Yes that is the only place in code that states a rule in regard to anything voltage drop.
 
Status
Not open for further replies.
Top