400A Service from Shop to Home

KaseyField01 said:
They are under the understanding that your reference for next size up with be for brand circuits, not a service entrance conductor.
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That is incorrect unless there is a local amendment to the NEC. The next size up rule can be applied to branch circuits, feeders, and service conductors. Around here a typical 200 amp service is usually #4/0 Al SE cable.
 
Thanks everyone on the 4/0 vs 250 to the shop/detached garage, or whatever. Either way, it will be just a couple of feet down the wall from the meter to the disconnects.

My primary concern is the overall plan. Suemarkp and Electrofelon had similar options, with the last one having 4 service entrance cables attached to the meter base, 2 to the house, 2 just a couple of feet away for the shop. One commenter wondered about the disconnects being visible from the house. This latest idea would have 2 disconnects at the house and 2 at the shop.
 
infinity said:
That is incorrect unless there is a local amendment to the NEC.
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Its a funny thing in Oregon most licensed electricians are "Journeyman" electricians while they are licensed make any electrical installation they are technically not allowed to do load calculations and or "direct, supervise, or control the installation or alteration of an electrical service".
A General Supervising Electrician Is the only individual authorized to direct, supervise, or control the installation or alteration of an electrical service in this state.
See OAR 918-282-0140 (c)
Up north in WA state I believe its similar but called an "Electrical Administrator".
Since most residential service upgrade's are permitted 'over the counter' - no load calculation or electrical plans are required, submitted or reviewed thus technically no load calc.
And the work is often performed by a solo journeyman no supervising electrician on site.
Absent that calc or a person licensed to do one on site most inspectors presume the service load to be the main breaker rating, some may accept a phone call or email from the Supervising Electrician.
If a General Supervising Electrician or EE has performed a article 220 load calculation in the electrical plans the 4/0 should pass.
 
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tortuga said:
Absent that calc or a person licensed to do one on site most inspectors presume the service load to be the main breaker rating, some may accept a phone call or email from the Supervising Electrician.
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I'm curious as the why anyone would make that assumption? If I have an existing 100 service that is being upgraded to a 200 amp the load shouldn't exceed 100 amps or slightly more in an extreme case. Certainly the existing load wouldn't be greater than the 180 amp rating of the #4/0 Al conductors.
 
tortuga said:
Its a funny thing in Oregon most licensed electricians are "Journeyman" electricians while they are licensed make any electrical installation they are technically not allowed to do load calculations and or "direct, supervise, or control the installation or alteration of an electrical service".
A General Supervising Electrician Is the only individual authorized to direct, supervise, or control the installation or alteration of an electrical service in this state.
See OAR 918-282-0140 (c)
Up north in WA state I believe its similar but called an "Electrical Administrator".
Since most residential service upgrade's are permitted 'over the counter' - no load calculation or electrical plans are required, submitted or reviewed thus technically no load calc.
And the work is often performed by a solo journeyman no supervising electrician on site.
Absent that calc or a person licensed to do one on site most inspectors presume the service load to be the main breaker rating, some may accept a phone call or email from the Supervising Electrician.
If a General Supervising Electrician or EE has performed a article 220 load calculation in the electrical plans the 4/0 should pass.
Click to expand...
I agree with the load calculation thats what a signing supervisor is for or an electrical engineer, not clear on not being able to tear down or alter a service as a general journeyman electrician in the state of Oregon I guess.

I have always been told by both local inspector and the state inspectors office a auxiliary building on a residence with a 200amp service must have 250kcmil alum wire going to it. If I am incorrect then I guess I oversize my shops I do for customers. So be it I guess but I've seen buildings fail for this upon inspection.

Why would the NEC have the de rate table for a dwelling unit for service conductors if the table shows 4/0 conductors will.work for the same application? I am not arguing this point, I would simple like to know if someone can tell me that would he great. I like learning as well. Sorry if I de railed the thread!

Kasey
 
KaseyField01 said:
Why would the NEC have the de rate table for a dwelling unit for service conductors if the table shows 4/0 conductors will.work for the same application? I am not arguing this point, I would simple like to know if someone can tell me that would he great. I like learning as well. Sorry if I de railed the thread!
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For a dwelling, the thought is not everything will be on at the same time.
As for 4/0 to a remote building, if the load will not exceed 180A, then you can use the next size up rule and use the 4/0.
 
KaseyField01 said:
Why would the NEC have the de rate table for a dwelling unit for service conductors if the table shows 4/0 conductors will.work for the same application? I am not arguing this point, I would simple like to know if someone can tell me that would he great. I like learning as well. Sorry if I de railed the thread!
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Because for #4/0 Al it just works out that way. For other sizes the 83% rule does not work out that way. Bottom line is if the load is 180 amps or less #4/0 Al is permitted by the NEC to be protected at 200 amps.
 
infinity said:
I'm curious as the why anyone would make that assumption? If I have an existing 100 service that is being upgraded to a 200 amp the load shouldn't exceed 100 amps or slightly more in an extreme case. Certainly the existing load wouldn't be greater than the 180 amp rating of the #4/0 Al conductors.
Click to expand...
All I can say is its a bit of tradition and like most traditions not super logical.
When I have ran into it years ago I was given two choices provide a article 220 load calculation or provide wire matches the breaker handle.
And I am a supervising electrician LOL,
keep in mind its a little different out west, these are the same inspectors that consider any exposed SE cable as 'subject to physical damage'.
In the town south of me there was visiting east coast sparky did a service for his mom (he legally can under a homeowner permit) like you guys do in NJ; nice SE exposed cable neatly strapped up some siding to one of those cute little SE cable weather heads, and it got turned down 250.30(B), he called for some assistance, but nope nothing I could do service had to be in pipe.
I know a larger EC that had to repull feeders in a new strip mall, since they had guys from CA.
These were empty shells for a unknown tenant there was no 'tenant' just an empty panel so the load calc is whatever the breaker handle is, I also could not help them.


KaseyField01 said:
not clear on not being able to tear down or alter a service as a general journeyman electrician in the state of Oregon I guess.
Click to expand...

If your a General Journeyman electrician you'r licensed to make any installation you want in the state, including a service. But the General Supervisor or EE is technically the only one who can 'sign off' on a load calculation (and your job plan), you can assist the supervisor and get all the nameplate data and run the numbers just they need to 'sign off' on it, or if your at a larger an EE can stamp it. In Oregon there is very little difference between a EE and a Supervising Electrician.
 
@KaseyField01
Calculated load. I had a 3 family with 3 (60A) services that I changed to (3) 100A services with a 3 gang meter socket. The SE cable from the weather head was 4/0 because the load calculation showed it was large enough for the building.

The fact that that 4/0 could be subjected to 300 amps total means nothing
 
Yes, Kaseyfield01, I'm learning as well. As many have said before, it can boil down to differences in AHJ. In my case, the runs to the shop will be single digit feet so wire size is not a big deal. I can easily upsize. I've been actually thinking of 250 to the house with the longer run, just because it's my house, lol.

I'm still focusing on my last comment before: My primary concern is the overall plan. Suemarkp and Electrofelon had similar options, with the last one having 4 service entrance cables attached to the meter base, 2 to the house, 2 just a couple of feet away for the shop. One commenter wondered about the disconnects being visible from the house. This latest idea would have 2 disconnects at the house and 2 at the shop.

... and best practices around that related to disconnects, economy, how they might affect generator or solar future proofing, etc.
 
I have a former co-worker who moved from CA to OR and they were surprised by some of the strictness up there compared to here. Specifically this topic came up. The way it was explained was that the existence of a load calc doesn't prevent someone from adding additional load. Requiring the larger wire provides greater protection, for whatever that's worth...
 
Im with ya! I miss understood your post!!
tortuga said:
All I can say is its a bit of tradition and like most traditions not super logical.
When I have ran into it years ago I was given two choices provide a article 220 load calculation or provide wire matches the breaker handle.
And I am a supervising electrician LOL,
keep in mind its a little different out west, these are the same inspectors that consider any exposed SE cable as 'subject to physical damage'.
In the town south of me there was visiting east coast sparky did a service for his mom (he legally can under a homeowner permit) like you guys do in NJ; nice SE exposed cable neatly strapped up some siding to one of those cute little SE cable weather heads, and it got turned down 250.30(B), he called for some assistance, but nope nothing I could do service had to be in pipe.
I know a larger EC that had to repull feeders in a new strip mall, since they had guys from CA.
These were empty shells for a unknown tenant there was no 'tenant' just an empty panel so the load calc is whatever the breaker handle is, I also could not help them.




If your a General Journeyman electrician you'r licensed to make any installation you want in the state, including a service. But the General Supervisor or EE is technically the only one who can 'sign off' on a load calculation (and your job plan), you can assist the supervisor and get all the nameplate data and run the numbers just they need to 'sign off' on it, or if your at a larger an EE can stamp it. In Oregon there is very little difference between a EE and a Supervising Electrician.
Click to expand...
 
bmaclaff said:
... and best practices around that related to disconnects, economy, how they might affect generator or solar future proofing, etc.
Click to expand...
What I often do is set one panel for battery or generator backed 'critical loads', this is typically a 60 - 100A feeder/panel just basic lights and refrigeration etc. then everything else goes in a 200A panel/feeder or service lateral.
 
KaseyField01 said:
Why would the NEC have the de rate table for a dwelling unit for service conductors if the table shows 4/0 conductors will.work for the same application?
Click to expand...
Because the dwelling unit conductor size is based on a calculated load of 200 amps. The round up rule that permits you to use 4/0 on a 200 amp breaker is based on a calculated load of 180 amps or less.
 
AC\DC said:
How come you like that versus using an interlock kit just curious
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Good question, and I am doing a interlock kit on my own modest home, but for higher end homes (320 - 400A service) the solar/storage guys we work for install these backup inverters:
www.sol-ark.com

12K Essentials

Sol-Ark® 12K-2P Essentials solar hybrid inverter is a powerful partial home backup that is scalable, plug-n-play, and NEM 3.0 ready. Learn more.
www.sol-ark.com www.sol-ark.com
or a propane generator with a ATS.
 
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