Why run 3/0 cu for residential 200A service?

[Flatpad]

Why would someone run 3/0 cu for a residential service? I've have now seen this for the third time and have to ask. I have been to 3 separate houses, all built in the last 4-6 years, all done by different electrician. The only thing that is similar is that the houses are all powered by JCP&L, I usually work in PSE&G territory.

What reason would someone have to use the bigger wire? I could understand seeing 1 house like that, maybe the contractor had some left over. But 3...?

 

[iwire]

Perhaps the homes where supplied 208/120 utility source.

As you can see you can only use the smaller conductors if it is a 120/240 service.

(6) 120/240-Volt, 3-Wire, Single-Phase Dwelling Services
and Feeders. For individual dwelling units of onefamily,
two-family, and multifamily dwellings, conductors,
as listed in Table 310.15(B)(6), shall be permitted as
120/240-volt, 3-wire, single-phase service-entrance conductors,
service-lateral conductors, and feeder conductors
that serve as the main power feeder to each dwelling unit
and are installed in raceway or cable with or without an
equipment grounding conductor. For application of this section,
the main power feeder shall be the feeder between the

 

[Flatpad]

These were definitely 120/240 services, I tested the voltage on 2 of them for other reasons, and they were right smack in the middle of suburbia

I guess it was just a coincidence. :thumbsup:

 

[iwire]

These were definitely 120/240 services, I tested the voltage on 2 of them for other reasons, and they were right smack in the middle of suburbia

I guess it was just a coincidence. :thumbsup:

Some folks just don't like to use the minimum.

 

[Dennis Alwon]

Years ago I did that from the meter to the panel when they were side x side because I did so many 400 amp services with 2- 200 amp panels that 3/0 is required. I always had pieces of 3/0 and copper was cheap so I would use it rather than go to the supplier to get 2/0. Saved time

 

[petersonra]

it would not surprise me at all to find that whoever decided such things decided not to stock 2/0.

the guy in charge here refuses to buy #3 for some reason so if I need #3 I get #2, sometimes even if I put #3 on the BOM.

 

[north star]

= =

Had an electrician tell one time, that the larger size was for future
expansion, ..."if" they decided to add more stuff later.

& &

 

[Dennis Alwon]

= =

Had an electrician tell one time, that the larger size was for future
expansion, ..."if" they decided to add more stuff later.

& &

It is amazing to me how many os us EC got licenses and did not know squat. I remember being told so many wives tales that I took them as gospel. I don't believe any of them were correct.

Two that come to mind is 100' run of conduit and a JB was needed and the other was that the neutral could be dropped one size. Well we know that the 100' rule is not correct and the other one could be true but if the calculated load was less the neutral could be as small as the GEC- a #4 for a 200 amp service.

 

[Flatpad]

I still hear long time electrician, some of them with contractor licenses, saying how you can't splice in a panel. :jawdrop: