# 400 amp overhead



## Hexamexapex (Jun 9, 2012)

I've never done a 400 amp overhead service. I was pondering the logistics of it all and have a few questions. I have never seen 3in riser or weatherhead on a residential service. Is this common for 120/240 single phase? I'm assuming POCO would run 600 aluminum from the transformer, but that seems like awfully big wire to be supported. Any thoughts? I believe our POCO supplies 400 amp meters so I don't think a CT would be needed.


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## RePhase277 (Feb 5, 2008)

Use 600 kcmil aluminum in the riser. A 320 amp socket and two 200 A disconnects.


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## Rollie73 (Sep 19, 2010)

We have to use a CT cabinet and meter base for anything over 300 amps here. AHJ and POCO metering requirement. 

Same as we must "cold meter" any service over 240 volts regardless of the amperage.

I still use a 3" mast and run 3 750 mcm AL conductors to the main switch......through the CT cabinet to the distribution panels.


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## Toto (Jul 27, 2011)

I did it way back when I didn't plan jobs very well. It got a little tough, but actually just the same as a 200 amp service except wire is heavy and not flexible.


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## Hexamexapex (Jun 9, 2012)

InPhase277 said:


> Use 400 kcmil aluminum in the riser. A 320 amp socket and two 200 A disconnects.


If the house was originally a 200amp service then POCO would need to come out and resize their service conductors right?

I see by your response that the wiring doesn't necessarily need to be rated for 400amps. I'm pretty confident in the installation of the two 200amp disconnects (load side). Supply side I haven't quite got my head around......getting closer though.


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## Toto (Jul 27, 2011)

Are you going through a roof or on a pole or what?


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## Toto (Jul 27, 2011)

Hexamexapex said:


> If the house was originally a 200amp service then POCO would need to come out and resize their service conductors right?
> 
> I see by your response that the wiring doesn't necessarily need to be rated for 400amps. I'm pretty confident in the installation of the two 200amp disconnects (load side). Supply side I haven't quite got my head around......getting closer though.


The POCO did not resize on mine and it burnt through the neutral about 5 years later. Coincidence? More than likeley.

If you buy the panel and look at it it's pretty simple actually. Not much going on in there.


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## Hexamexapex (Jun 9, 2012)

Toto said:


> Are you going through a roof or on a pole or what?


Meter cabinet, riser, weatherhead, etc would be located on the back of the house, not through the roof, anchored to the brick. Should have plenty of clearance in that location plus it's the preferred access point for utility.


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## Hexamexapex (Jun 9, 2012)

Rollie73 said:


> We have to use a CT cabinet and meter base for anything over 300 amps here. AHJ and POCO metering requirement.
> 
> Same as we must "cold meter" any service over 240 volts regardless of the amperage.
> 
> I still use a 3" mast and run 3 750 mcm AL conductors to the main switch......through the CT cabinet to the distribution panels.


I'll need to find out when our POCO and AHJ requires CT. Don't think I would need 750mcm.... 600 most likely. Although inphase recommends only 400...which wouldn't be rated for 400.


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## RePhase277 (Feb 5, 2008)

Hexamexapex said:


> If the house was originally a 200amp service then POCO would need to come out and resize their service conductors right?
> 
> I see by your response that the wiring doesn't necessarily need to be rated for 400amps. I'm pretty confident in the installation of the two 200amp disconnects (load side). Supply side I haven't quite got my head around......getting closer though.



The POCO _might_ resize their drop, if a significant amount of load was added. But I have seen plenty of #2 triplex dropped to 400 A services.


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## Toto (Jul 27, 2011)

Don't underestimate the weight. We wound up three people on a ladder trying to shove the copper into the conduit. It took an hour of hard work at least. Of course mine was on a pole with the ladder tied off. Wouldn't go down like that now. Just have a good plan for getting that weight into the air and you'll be fine.


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## RePhase277 (Feb 5, 2008)

Hexamexapex said:


> I'll need to find out when our POCO and AHJ requires CT. Don't think I would need 750mcm.... 600 most likely. Although inphase recommends only 400...which wouldn't be rated for 400.


The conductors only need be sized for the load. So, you could have a 400 A service with #10 riser if the load was 30 A or less. I miss typed earlier. Should be 600 aluminum. I size my residential service entrance conductors by 310.15(B)(7)


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## Hexamexapex (Jun 9, 2012)

InPhase277 said:


> The POCO might resize their drop, if a significant amount of load was added. But I have seen plenty of #2 triplex dropped to 400 A services.


And no problems arose? Any problems with code compliance? I'm guessing....no?


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## RePhase277 (Feb 5, 2008)

Hexamexapex said:


> And no problems arose? Any problems with code compliance? I'm guessing....no?


Their drop doesn't need to comply with NEC ampacities. They use the "free air" ampacity, which gives small wires large ampacities due to being cooled better by air.

Do a load calc and figure your connected load. Contact the POCO engineer and tell him your numbers. He will determine whether the existing drop and transformer need upgrading.


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## Hexamexapex (Jun 9, 2012)

InPhase277 said:


> The conductors only need be sized for the load. So, you could have a 400 A service with #10 riser if the load was 30 A or less. I miss typed earlier. Should be 600 aluminum. I size my residential service entrance conductors by 310.15(B)(7)


 I see what your saying now. I don't think the calculated load would be over 300. But I wouldn't know for sure till contractor gets me appliance, HVAC, etc lists. Big house though...4000sqft finished. 2800sqft unfinished.


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## Rollie73 (Sep 19, 2010)

Hexamexapex said:


> I'll need to find out when our POCO and AHJ requires CT. Don't think I would need 750mcm.... 600 most likely. Although inphase recommends only 400...which wouldn't be rated for 400.


You may be just fine with 600's My answers are based on the Canadian Electrical Code. I only answered to give you some idea of the different scenarios available to you.:thumbsup:


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## Hexamexapex (Jun 9, 2012)

Rollie73 said:


> You may be just fine with 600's My answers are based on the Canadian Electrical Code. I only answered to give you some idea of the different scenarios available to you.:thumbsup:


I do appreciate the advice Rollie.


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## Rollie73 (Sep 19, 2010)

Hexamexapex said:


> I do appreciate the advice Rollie.


 :thumbsup::thumbsup:


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## 220/221 (Sep 25, 2007)

I have one coming up that requires 600's and I will bet that the POCO won't go bigger than 2/0 triplex. I am using a 3" mast/weatherhead because I have had the materials kicking around my warehouse for several years

Here, we can also run parallel 2" masts with 200A conductors. It kills me to do all that work and have POCO crimp on their small triplex


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## Hexamexapex (Jun 9, 2012)

220/221 said:


> I have one coming up that requires 600's and I will bet that the POCO won't go bigger than 2/0 triplex. I am using a 3" mast/weatherhead because I have had the materials kicking around my warehouse for several years
> 
> Here, we can also run parallel 2" masts with 200A conductors. It kills me to do all that work and have POCO crimp on their small triplex


Ah...see I was considering the idea of installing another mast. Just not quite sure what would be
more work. Tearing down the old 2" mast and installing a 3" with new 3" weatherhead. Or just throwing up another 200 as you said "parallel".


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## Cletis (Aug 20, 2010)

InPhase277 said:


> Use 600 kcmil aluminum in the riser. A 320 amp socket and two 200 A disconnects.


Your talking Tennessee here. they do things el cheapo there



Hexamexapex said:


> Meter cabinet, riser, weatherhead, etc would be located on the back of the house, not through the roof, anchored to the brick. Should have plenty of clearance in that location plus it's the preferred access point for utility.


Here is what you do, go get you some fine 4/0 SEU x 2. Run them parallel into the meter base. You got yourself a hillbilly 320/400 and it's cheap and it will pass. 



InPhase277 said:


> Their drop doesn't need to comply with NEC ampacities. They use the "free air" ampacity, which gives small wires large ampacities due to being cooled better by air.
> 
> Yes
> 
> Do a load calc and figure your connected load. Contact the POCO engineer and tell him your numbers. He will determine whether the existing drop and transformer need upgrading.


First of all, your poco engineer probably won't give a crap or even send the trouble crew out to replace it in reality, especially if their a for profit company and if they do I'd doubt they run more than a 1/0 triplex even if he does a historical data and it show it needs it which I doubt very much. The old one will probably stay their for years


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## Hexamexapex (Jun 9, 2012)

Cletis said:


> Your talking Tennessee here. they do things el cheapo there
> 
> Here is what you do, go get you some fine 4/0 SEU x 2. Run them parallel into the meter base. You got yourself a hillbilly 320/400 and it's cheap and it will pass.


I agree the 4/0 paralleled from meter base is the plan for the 2 main breaker 200 amp panels. Next item of business is getting a load calc so I can size my riser wires appropriately. 4/0 in the riser won't be adequate for 300 amp load calc.


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## Cletis (Aug 20, 2010)

Hexamexapex said:


> I agree the 4/0 paralleled from meter base is the plan for the 2 main breaker 200 amp panels. Next item of business is getting a load calc so I can size my riser wires appropriately. 4/0 in the riser won't be adequate for 300 amp load calc.


I meant 2x4/0 as your riser into your meter than 2x4/0 out to your 200 amp main breaker panels


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## Hexamexapex (Jun 9, 2012)

Cletis said:


> I meant 2x4/0 as your riser into your meter than 2x4/0 out to your 200 amp main breaker panels


Ah...parallel the 4/0 out of the riser....interesting. So that would mean POCO would have two of each wire to splice to their service drop. They will do this and it will pass? Great idea...


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## bmailman20 (Jan 4, 2013)

I've only done this once. We used a 400A CT cabinet with 500 cu feeding it. I'm pretty sure the riser was 4" rigid. Sending the copper up wasn't as bad as getting the pipe up in the first place. What a bitch!


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## mbednarik (Oct 10, 2011)

Just did a 400 last week. 2 2" EMT risers. Makes good sense money wise. The little extra labor will be saved by using cheaper weather heads, conduit and such, even though there is double everything. For example the service heads, a 2" was $9 and the 3" was $50. I paralleled 3/0 CU simpull. We had the mast up, wired pulled and terminated in about 2 hours from the drop to MDP.


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## B4T (Feb 10, 2009)

The POCO here would run a 1/0 AL service drop from the pole.. biggest they have...

If they feel the load is more.. they will parallel the service drop..


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## Ultrafault (Dec 16, 2012)

You can put 4 4/0 and 2 2/0 in a 2 1/2 inch conduit why would you run 2 conduits?


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## Hexamexapex (Jun 9, 2012)

Ultrafault said:


> You can put 4 4/0 and 2 2/0 in a 2 1/2 inch conduit why would you run 2 conduits?


Your talkin 4 hots (4/0) and 2 neutrals (2/0)?


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## Hexamexapex (Jun 9, 2012)

Ultrafault said:


> You can put 4 4/0 and 2 2/0 in a 2 1/2 inch conduit why would you run 2 conduits?


I'm not so sure about that. I believe I would exceed the 40% raceway fill threshold by placing all of those wires in 2 1/2 inch conduit. Specifically schedule 40 PVC. What am I missing?


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## Hexamexapex (Jun 9, 2012)

Hexamexapex said:


> I'm not so sure about that. I believe I would exceed the 40% raceway fill threshold by placing all of those wires in 2 1/2 inch conduit. Specifically schedule 40 PVC. What am I missing?


Let me clarify...using table 5 I am exceeding 40% fill. If I use table 5A then Im just under the 40% fill. Currently trying to differentiate between the two tables.


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## Ultrafault (Dec 16, 2012)

PVC_40, Size: 2-1/2
Nipple size: 2

Conduit Notes: ( 37.0% of 4.695 sq.in. )

Nipple Notes: ( 52.9% of 3.291 sq.in. )

MINIMUM SIZE FOR:
Total Wire Area: 1.7394 sq.in.
2 x 2/0 AWG (THHN, THWN, THWN-2) Wire(s)
** - Area: 0.4446 sq.in.
4 x 4/0 AWG (THHN, THWN, THWN-2) Wire(s)
** - Area: 1.2948 sq.in.


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## Ultrafault (Dec 16, 2012)

What are your numbers?


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## Hexamexapex (Jun 9, 2012)

Ultrafault said:


> PVC_40, Size: 2-1/2
> Nipple size: 2
> 
> Conduit Notes: ( 37.0% of 4.695 sq.in. )
> ...


I think I see the discrepancy. I am calculating for TW, THW, THHW......not THHN, THWN.....


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## kennydmeek (Sep 12, 2009)

Poco here uses the same itty bitty @ss wire they use for 200s...they heavy up the trannys if necessary but inspectors just shake their heads on the drop..

I use 750 if AL or 600 if CU..3" PVC with strut and straps.


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## Hexamexapex (Jun 9, 2012)

kennydmeek said:


> Poco here uses the same itty bitty @ss wire they use for 200s...they heavy up the trannys if necessary but inspectors just shake their heads on the drop..
> 
> I use 750 if AL or 600 if CU..3" PVC with strut and straps.


Base on your experience would POCO object to connecting their drop to a paralleled set of service conductors? 4 4/0 and 2 2/0....parallel from meter to two 200 amp main breakers.


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## kennydmeek (Sep 12, 2009)

Hexamexapex said:


> Base on your experience would POCO object to connecting their drop to a paralleled set of service conductors? 4 4/0 and 2 2/0....parallel from meter to two 200 amp main breakers.


Why would you want to do that? You only need 2 4/0s(al) from the meter to each breaker...POCO doesn't look past the meter in my world.


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## Hexamexapex (Jun 9, 2012)

kennydmeek said:


> Why would you want to do that? You only need 2 4/0s(al) from the meter to each breaker...POCO doesn't look past the meter in my world.


It would be an upgrade to 400 amp service. Currently it's a 200 amp service with 2 4/0 and 1 2/0 up the riser. Just thinking of other options other than running 3" conduit up to 3" weatherhead with 600 aluminum.


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## wireman64 (Feb 2, 2012)

kennydmeek said:


> Poco here uses the same itty bitty @ss wire they use for 200s...they heavy up the trannys if necessary but inspectors just shake their heads on the drop..
> 
> I use 750 if AL or 600 if CU..3" PVC with strut and straps.


My poco used to like running # 6 al triplex to basically everything under 400 amps , man that stuff used to heat up when you got a good load on it in the summer time


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