Voltage drop and wire size

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The utility meter and breaker enclosure is 320 feet from my home panel. Minimum feeder wire size for my 200 amp panel is 4/0 aluminum and 2/0 copper. Would you suggest I up the wire size to 250 aluminum or 4/0 copper? I will not have any large loads at the house. No AC and radiant heating only. Standard refrigerator, gas oven, electric clothes dryer, microwave and LED lighting.

thanks,
John
 
Location
NE (9.06 miles @5.9 Degrees from Winged Horses)
Occupation
EC - retired
The utility meter and breaker enclosure is 320 feet from my home panel. Minimum feeder wire size for my 200 amp panel is 4/0 aluminum and 2/0 copper. Would you suggest I up the wire size to 250 aluminum or 4/0 copper? I will not have any large loads at the house. No AC and radiant heating only. Standard refrigerator, gas oven, electric clothes dryer, microwave and LED lighting.

thanks,
John

4/0-4/0-2/0 Al is a typical triplexed cable.

Upsize to 250 Al if you desire. Don’t min size the conduit, go up.

Use copper only if you have an excessive amount of cash laying around getting moldy.
 

kwired

Electron manager
Location
NE Nebraska
That doesn't make any sense. Is it a local amendment?
Ignorant inspector, or someone above the inspector.

OP mentioned radiant heating, so depending on how much heating there is, may not even be close to needing 200 amps - 4/0 still a good idea simply for voltage drop reasons. If that radiant heat is all 240 volts no reason the neutral needs to even be 2/0, though it is common practice some places to allow two sizes smaller without needing to show neutral load calculations.

If it were two phases and neutral of a wye system - full size neutral may be necessary - again would depend on actual neutral load though. If all that radiant heat is 208 volts - it is not utilizing the neutral and that particular load can be ignored when calculating neutral load.
 
Yes, I think it is just the inspectors preference. I am here in Colorado. Also, the radiant heating works off a boiler. Heated water travels through tubes in the concrete slab. Power used is only for recirculating pump.

thanks
John
 
I am thinking 4/0 aluminum would be fine for the 320' distance. I may up size to 250 aluminum. Will get a quote on Monday to see the cost difference. If it's not substantial, then I will just go with 250 and not worry about it.
 

kwired

Electron manager
Location
NE Nebraska
Yes, I think it is just the inspectors preference. I am here in Colorado. Also, the radiant heating works off a boiler. Heated water travels through tubes in the concrete slab. Power used is only for recirculating pump.

thanks
John
Thought you meant electric radiant heat - that means your actual load is even less than I first thought and that 200 amps of supply is likely way more than actual demand will ever reach. 4/0 conductor for that length is still good at keeping voltage drop low for no more load than you are likely to see.
 
Thought you meant electric radiant heat - that means your actual load is even less than I first thought and that 200 amps of supply is likely way more than actual demand will ever reach. 4/0 conductor for that length is still good at keeping voltage drop low for no more load than you are likely to see.

Sounds good, thanks for the help.
 

ActionDave

Chief Moderator
Staff member
Location
Durango, CO, 10 h 20 min from the winged horses.
Occupation
Licensed Electrician
Yes, I think it is just the inspectors preference. I am here in Colorado. Also, the radiant heating works off a boiler. Heated water travels through tubes in the concrete slab. Power used is only for recirculating pump.

thanks
John

I'm in Colorado too. The inspector can prefer whatever he wants but he can only enforce what is in the NEC. There is no reason to pull a full sized neutral on a house. I would politely disagree with him and ask for the documentation that requires this. If he doesn't have any but won't budge I would go over his head.
 

oldsparky52

Senior Member
I am thinking 4/0 aluminum would be fine for the 320' distance. I may up size to 250 aluminum. Will get a quote on Monday to see the cost difference. If it's not substantial, then I will just go with 250 and not worry about it.

Looks like the VD for that distance using 4/0 AL is 2.67% of 240V at 100' and 5.33% at 200-amps.

Have you done a load calculation? What is the sum of the 120V loads, and the sum of the 240V loads?
 
I am thinking 4/0 aluminum would be fine for the 320' distance. I may up size to 250 aluminum. Will get a quote on Monday to see the cost difference. If it's not substantial, then I will just go with 250 and not worry about it.

My rule of thumb for a house is 70 Amp max, so using that number, 4/0 is 2.2% VD and 250 is 1.8% VD. IMO 4/0 is fine since 2.2% is pretty low plus that 70 amps would only happen for very brief periods (if at all).
 
In the case I cited, they are effectively one and the same. The inspector has no technical supervision and his management just rubber stamps his recommendations and code interpretations.

What is "the case I cited" ? I assume you are talking about some of your jurisdictions in Texas. Actually here in upstate NY, its kinda a muddled distinction too. Its mostly private third party electrical inspections and the inspector can kinda interpret things how he likes. I guess in theory one would expect the entire inspection agency to have the same interpretation so the agency could be thought of as the AHJ....Here though you can just call a different inspector if you dont like the one you have.
 

kwired

Electron manager
Location
NE Nebraska
I know, which is why I asked about any local amendments. I don't think there are any in Colorado.
To enforce a local amendment it has to be put into statutes - so there has to be a statute to quote that you are in violation of.

There may be many unofficial rules that get enforced because they are seldom if ever challenged.

If they are to formally cite a violation and fine you, force you to make a change, etc., they should need to have a statute to refer to that you are in violation of. If only statute they can come up with amounts to 20xx NEC with no amendments - then they must cite which part of the NEC is in violation.
 
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