# 400(320)A Residential Heavy Up



## kennydmeek (Sep 12, 2009)

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!


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## JohnJ0906 (Jan 22, 2007)

kennydmeek said:


> 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
> ...


Check with the POCO (power company) Kindorff and straps won't fly here if the mast supports the service drop. They also don't permit grounding in the meter base.

Separate bond between panels is not necessary

400 copper in the mast is enough - 310.15(B)(6)

Is the 4/0 SEU copper or aluminum?


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## kennydmeek (Sep 12, 2009)

4/0 AL. That's what they've been running in all the Mc Mansions around here. Where would you run the grounds from? How would you anchor the mast?


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## 480sparky (Sep 20, 2007)

kennydmeek said:


> 4/0 AL. That's what they've been running in all the Mc Mansions around here. Where would you run the grounds from? How would you anchor the mast?


4/0 al is too small since the 'cheat sheet' table 310.15(B)(6) doesn't apply. You must size from T310.16


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## JohnJ0906 (Jan 22, 2007)

kennydmeek said:


> 4/0 AL. That's what they've been running in all the Mc Mansions around here. Where would you run the grounds from? How would you anchor the mast?


To use Table 310.15(B)(6) the cable must carry the entire house load. So 4/0 AL is good for a 200 amp service, but not for (2) 200 amp panels. I don't agree, but that's the NEC. FWIW, that isn't enforced around here - at least when I was doing residential. (2) 4/0 AL SEU cables to a 400 amp meter was SOP.

Grounds go the the service disconnect(s), in this case the panels.

Is the mast supporting the service drop?


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## Mike Guile (Jan 14, 2010)

*400amp*

I think everyone does it different. We used to add a service knob (emily knob) with a lag screw for support for drop. Then would run 2x2" EMT Conduits with 4/0-4/0-2/0 XHHW paralelled to meter. We bonded the 2-200 amp mains together and ran the grounding conductors you mentioned from one of the 200's. This setup took the load off the conduits (saving $$ no rigid) and you'll save a few more hundred I think using AL instead of Cu.


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## kennydmeek (Sep 12, 2009)

So...If I go from the panels, do I do separate grounds? Or bond the two and run one?

I've seen situations where Allegheny has uses the kindorff supporting the mast as support for the service drop and where the service drop was supported by the mast itself. It's a strong old brick wall. I don't see anything in Alleghenys's spec sheets specifying either or. Talking to a real person there who knows anything is nearly impossible.


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## kennydmeek (Sep 12, 2009)

There's one of those "emily knobs" Mike was talking about on the house right now...


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## Mike Guile (Jan 14, 2010)

*I'm at*

Well, where I'm at (not superstrict) they would let us bond the 2 panels with a #2Cu then run 1 #2 Cu to Water Pipe and same concept with Ground Rods. I'm sure others will chime in on the setup I described above,but, our inpector let it through. It was xhhw-2 (90C) ,but, something about the 90-75C (terminations) column technically makes it not ok I think??? Guru's ?? 460 amps - 360amps?

Didn't matter, because everyone ran this setup where we lived in rural indiana and it passed all the time.


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## Mike Guile (Jan 14, 2010)

*check puco*

it's more puco for that emily knob or rack decision? It depends on who's working that day if they will pass. They are only $15 bucks here. It's like a big thick horshoe with insulator with cotter type pin. Just drive the rack into some good wood with a 6" 0r 8" Lag screw (thick) then set in insulator. It works here.


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## kennydmeek (Sep 12, 2009)

JohnJ0906 said:


> To use Table 310.15(B)(6) the cable must carry the entire house load. So 4/0 AL is good for a 200 amp service, but not for (2) 200 amp panels. I don't agree, but that's the NEC. FWIW, that isn't enforced around here - at least when I was doing residential. (2) 4/0 AL SEU cables to a 400 amp meter was SOP.
> 
> 
> 
> > Shouldn't one of the tap rules apply since it's a short run straight to a 200A main?


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## oldschool (Aug 2, 2008)

trying to remember the last 400 amp service i did in Frederick County

4/0 AL was OK to each 200 amp panel

water pipe from well was plastic so the only ground was #6 CU from one panel thru the other out to 2 ground rods

inspector wanted one #6 from each panel to one ground rod

call the county, talk to Bob Ensor, chief inspector and save yourself some hassle


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## Mike Guile (Jan 14, 2010)

*Tap*

I don't know a thing about tap rules. Tap rule Guru's? 

It basically comes down to your inspector anyhow. Go find a recent 400 amp install in your area. open it up and see what they did and passed. That's the best way. We used to run #2 Al xhhw-2 for on a 100 amp breaker in one area. But, in another area the inspector made us use the 75C column and put a 90 amp breaker on it. It all comes down to what they want unfortunately , kind of like woman.


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## kennydmeek (Sep 12, 2009)

oldschool said:


> water pipe from well was plastic so the only ground was #6 CU from one panel thru the other out to 2 ground rods


Allegheny's the entity looking for 2 ground rods on the service per se...I'll give Bob a call tomorrow and get his take. 

Seems like a friendlier bunch downtown since the Ron Krom/Chuck Kline days. It's been a little while since I've done work in this jurisdiction...Used to do lots of commercial stuff here when those guys were around. Some times you could have fun with 'em....sometimes they'd have fun with you.


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## MDShunk (Jan 7, 2007)

Kennedy, I build most of my services in Allegheny territory. You're okay with what you propose. When you call for your work request number, you'll want to make sure you tell them what size conductors you plan to put in your riser, since they don't always carry the huge H-Taps on the trucks they send to retap services.

I generally build mine with PVC on Kindorf; mostly to save cost. I never support the drop off the riser anyhow. I always hang a knob or rack next to the weatherhead. 

Do you have a copy of their current rules book? The current edition has a grey cover. It has a lot of pictures, so you really can't go wrong. I think you can download it off their site too. 

"Customer Requirements For Electric Service"


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## kennydmeek (Sep 12, 2009)

MDShunk said:


> Kennedy, I build most of my services in Allegheny territory. You're okay with what you propose. When you call for your work request number, you'll want to make sure you tell them what size conductors you plan to put in your riser, since they don't always carry the huge H-Taps on the trucks they send to retap services.
> 
> I generally build mine with PVC on Kindorf; mostly to save cost. I never support the drop off the riser anyhow. I always hang a knob or rack next to the weatherhead.
> 
> ...


That's awesome! I was only able to find an abbreviated version. That detail is very helpful!


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## electric cj (Feb 27, 2010)

I was wondering were does every one keep getting this 500 copper size for 400 amp service. When the n.e.c states 400 KCM copper or 600 MCM alum. (Table 310.15(b)(6). Is there something I'm missing?


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## BEAMEUP (Sep 19, 2008)

electric cj said:


> I was wondering were does every one keep getting this 500 copper size for 400 amp service. When the n.e.c states 400 KCM copper or 600 MCM alum. (Table 310.15(b)(6). Is there something I'm missing?


Beats me??? (Table 310.15(b)(6) is pretty clear what size to run. :001_huh:


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## electric cj (Feb 27, 2010)

*400 amp service*

It seems people when installing a 400 amp service, seem to favor the 320 meter base, split into two 200amp service panel method. Why not just buy a all in one 400amp service panel? Ive been looking at the all in one panels online for about $1000 to $1400. You would simplify every thing, have a cleaner installation, and save time on the installation. I getting ready to install my first 400 amp panel just trying to get some pro and cons of the different methods. 

Thanks to every one on the form. This is a great site for an always ongoing education.


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## BEAMEUP (Sep 19, 2008)

electric cj said:


> It seems people when installing a 400 amp service, seem to favor the 320 meter base, split into two 200amp service panel method. Why not just buy a all in one 400amp service panel? Ive been looking at the all in one panels online for about $1000 to $1400. You would simplify every thing, have a cleaner installation, and save time on the installation. I getting ready to install my first 400 amp panel just trying to get some pro and cons of the different methods.
> 
> Thanks to every one on the form. This is a great site for an always ongoing education.


I've done it that way before and works well, it also depends on the layout of the house. I've done a 200 amp panel & a 200 amp disco in the garage & then ran 4/0 ser to the other end of a house because the kitchen and master suite and most of the heavy loads where there.

It just depends on the house.


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## Shockdoc (Mar 4, 2010)

I've always preferred a 6x6 X 12" or 24" troft mounted verticle in between both panels for twin 200 amp panels in basement or mounted horizontal underneath panels for back to back applications. I have not used type SE cable since 2002.


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## Shockdoc (Mar 4, 2010)

BEAMEUP said:


> I've done it that way before and works well, it also depends on the layout of the house. I've done a 200 amp panel & a 200 amp disco in the garage & then ran 4/0 ser to the other end of a house because the kitchen and master suite and most of the heavy loads where there.
> 
> It just depends on the house.


Here in LIPA country we are stuck with a 400 trans "s" cabinet for residential 400 amp services. Requirements do not let us make our own KOs , exit the cabinet through the rear and use type SE cable. I enjoyed using the 320 m/p in PA for 400 amp services, the 320 on LI is only accepted for 300 amp services, no SE cable allowed.


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