400(320)a Heavy Up

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kennydmeek

kennydmeek

Member
Location
Frederick MD
I've never done a 400(320)amp residential service before..Here's what I have in mind for overhead installation. Would appreciate any help hints or corrections....
3" EMT Riser to weatherhead 20' up secured with Kindorff and straps
500mcm copper from meter to lines in
4/0 SEU from meter can to 2 200amp Main Breaker panels
#6 solid from meter can to 2 ground rods 6'apart
#2 stranded from meter can to cold water entrance jumped across water meter

Does this sound right?
Should there be a separate bond between the 2 panels?
Any other considerations?

Thanks!
 
infinity

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
#4/0 AL SE cable is only good for 150 amps unless your under the 2005 or earlier NEC.
 
S

suemarkp

Senior Member
Location
Kent, WA
Occupation
Retired Engineer
For a dwelling, the service drop/lateral conductors only need to be 400 KCMil copper (310.15(B)(6)).

The pipe bonding wire need to be 1/0 copper (look at 250.66).

I still see 310.15(B)(6) as debatable in this case for the wires to each panel. Assuming no breaker in the meter, you're running Service Entrance Conductors, so 310.15(B)(6) should be usable. These are not feeders, so the limitation that the wires carry the entire load of the house do not apply. But the inspector may give you grief over that, and many say the intent is that the multiple sets of service entrance conductors each use table 310.16. If you use that table, you'll need 3/0 75C copper to each panel. A 4/0 75C conductor would be OK if the calculated load is 180A or less per panel. Not a good assumption to make in an ever changing residence.
 
T

ty

Senior Member
Location
3rd Rock from the Sun
suemarkp said:
For a dwelling, the service drop/lateral conductors only need to be 400 KCMil copper (310.15(B)(6)).

The pipe bonding wire need to be 1/0 copper (look at 250.66).

I still see 310.15(B)(6) as debatable in this case for the wires to each panel. Assuming no breaker in the meter, you're running Service Entrance Conductors, so 310.15(B)(6) should be usable. These are not feeders, so the limitation that the wires carry the entire load of the house do not apply. But the inspector may give you grief over that, and many say the intent is that the multiple sets of service entrance conductors each use table 310.16. If you use that table, you'll need 3/0 75C copper to each panel. A 4/0 75C conductor would be OK if the calculated load is 180A or less per panel. Not a good assumption to make in an ever changing residence.
Click to expand...

I agree.
4/0AL SEU to each panel.
 
infinity

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
suemarkp said:
I still see 310.15(B)(6) as debatable in this case for the wires to each panel. Assuming no breaker in the meter, you're running Service Entrance Conductors, so 310.15(B)(6) should be usable. These are not feeders, so the limitation that the wires carry the entire load of the house do not apply. But the inspector may give you grief over that, and many say the intent is that the multiple sets of service entrance conductors each use table 310.16.
Click to expand...

How do two sets of #4/0 SE cables feeding two separate 200 amp panels carry the entire load of the dwelling unit? Are you saying that this is not part of the requirement when using Table 310.15(B)(6)?
 
tkb

tkb

Senior Member
Location
MA
kennydmeek said:
I think it's been about 160 years...since those Mason and Dixon guys started drawing lines...:grin:
Click to expand...

I looked up where the Mason Dixon line is, I still don't see Maryland as "the south" even with the line at the PA\MD border.
Mid Atlantic at best.:D
 
T

ty

Senior Member
Location
3rd Rock from the Sun
infinity said:
How do two sets of #4/0 SE cables feeding two separate 200 amp panels carry the entire load of the dwelling unit? Are you saying that this is not part of the requirement when using Table 310.15(B)(6)?
Click to expand...

Why do they need to?
Each 4/0 SEU only needs to carry the load of the panel it serves, not Both.
 
V

Volta

Senior Member
Location
Columbus, Ohio
Section 310.15(B)(6) clearly requires any conductor "downsized" per that table to carry the entire load of the dwelling. It may only apply to service entrance, service lateral, or the 'main power' feeder. Not multiple feeders. 4/0 aluminum will be too small.
 
kennydmeek

kennydmeek

Member
Location
Frederick MD
tkb said:
I looked up where the Mason Dixon line is, I still don't see Maryland as "the south" even with the line at the PA\MD border.
Mid Atlantic at best.:D
Click to expand...

Yeah I know. I'm the only one here with a southern accent...but drive a couple hours into Virginia and you'd think you were in Alabama...:D
 
LarryFine

LarryFine

Master Electrician Electric Contractor Richmond VA
Location
Henrico County, VA
Occupation
Electrical Contractor
kennydmeek said:
Yeah I know. I'm the only one here with a southern accent...but drive a couple hours into Virginia and you'd think you were in Alabama...:D
Click to expand...
Hey! :mad: (;))





"Don't talk about Virginia like that!"

"What's wrong? You from Virginia?"

"No, Alabama!"
 
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