At what length do you upsize feeder wire to residence

[JoeNorm]

Services here are always at the street/transformer, so it's always some distance to the main panel of the house. 4/0 triplex is the standard for a 200amp service around here.

My question is when you start to consider upsizing the wire due to distance and voltage drop concerns. There is never a house in this case, so a load calc is difficult. And we all know average houses very rarely draw more than even 100 amps.

So how is this approached? Should the calc be done assuming a full load, say 180amps? That seems crazy but perhaps safest? Thoughts?

 

[garbo]

Services here are always at the street/transformer, so it's always some distance to the main panel of the house. 4/0 triplex is the standard for a 200amp service around here.

My question is when you start to consider upsizing the wire due to distance and voltage drop concerns. There is never a house in this case, so a load calc is difficult. And we all know average houses very rarely draw more than even 100 amps.

So how is this approached? Should the calc be done assuming a full load, say 180amps? That seems crazy but perhaps safest? Thoughts?

In my area the service lateral from transformer to attachment to house or building is ultility responsibility and always undersized. I did a 800 amp 240 volt three phase service for a plastic injection shop that ran what some would say hot & heavy 24/6. Load was usually around 600 amps around the clock but Ultility only ran 4/0 aluminum wire that if it was in conduit would probably only be good for 160 amps. Wire in free air can withstand higher ampere but not triple. Same thing when I was upgrading an underground service in center city. Installed a 100 & 200 amp meter and Ultility told me that the 75 year old frayed rubber & cloth covered # 6 copper wire was large enough. Yea right a 60 amp ancient wire is big enough to feed 300 amps. They do not have to follow the NEC. So if the service cable is less then around 60' I would not worry about voltage drop. The NEC allows I believe a total of 5% voltage drop between the service and feeders. Luckily with wide spread smart use of LED'S & energy rated appliances loads have gone down. Until at least you get one or two EV'S that each might need 30 to 50 amp charging circuits.

 

[petersonra]

Services here are always at the street/transformer, so it's always some distance to the main panel of the house. 4/0 triplex is the standard for a 200amp service around here.

My question is when you start to consider upsizing the wire due to distance and voltage drop concerns. There is never a house in this case, so a load calc is difficult. And we all know average houses very rarely draw more than even 100 amps.

So how is this approached? Should the calc be done assuming a full load, say 180amps? That seems crazy but perhaps safest? Thoughts?

chances are if you have a load calc that comes out to 180 Amps, the real load will only rarely approach 100 Amps.

I don't think there is any standard for how to do VD calcs, but IMO it should be done based on the actual load and not the load calculation.