# #2 xhhw aluminum



## Hexamexapex (Jun 9, 2012)

Keeping with my ampacity theme of the week I have a wiring method that must be scrutinized for code compliance.....and also to further my understanding of type SE cable ampacity derating. Here is the situation:
We (my company) wire an 8 unit apartment building about once a month. Our service entrance cable is #2 XHHW aluminum rated at 90C. We use 100 amp breakers on our service equipment for the main disconnect. I may have missed something but according to NEC we must use the 60C column for type SE cable. According to table 310.16 this puts out #2 XHHW aluminum at 75amps. Am I wrong in thinking we need to move up to 1/0? We have done at least 15 of these and everyone passes. Local jurisdiction?


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## Cletis (Aug 20, 2010)

Think it's #1 Al if SEU for main. 1/0 if feeder


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## Hexamexapex (Jun 9, 2012)

Cletis said:


> Think it's #1 Al if SEU for main. 1/0 if feeder


We are running feeder and our installation method is not underground. We go right through each units ceiling all the way to supply side.


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## Cletis (Aug 20, 2010)

Hexamexapex said:


> We are running feeder and our installation method is not underground. We go right through each units ceiling all the way to supply side.


oh. then yes 1/0 per 310.16 60C column yes


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## Hexamexapex (Jun 9, 2012)

Or maybe we use #1 but use 90amp breaker.


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## Hexamexapex (Jun 9, 2012)

Cletis said:


> oh. then yes 1/0 per 310.16 60C column yes


Maybe out local jurisdiction doesn't care or they don't know.


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## Cletis (Aug 20, 2010)

Hexamexapex said:


> Or maybe we use #1 but use 90amp breaker.


Yes. That's what I've been doing last year or so. I'm stocked up on 90's in garage


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## GREGNC (Nov 13, 2007)

Wouldnt # 2. Alum would be ok with 100amp
Cb. Acording to 310.15B7


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## Hexamexapex (Jun 9, 2012)

GREGNC said:


> Wouldnt # 2. Alum would be ok with 100amp
> Cb. Acording to 310.15B7


If you meant 310.15(b)(6) then yes I see that. But if you look at 338.10(4)(a) it will lead you to 334.80. Which leads us back to 310.16, 60C column. That's the important one.


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## Hexamexapex (Jun 9, 2012)

So when is it ok to use Table 310.15(b)(6)? Seems like table 310.16, 60C column negates the values in 310.15(b)(6). Anyone?


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## Hippie (May 12, 2011)

#2 al has always been good for a 100A service and main feeder (if coming off a disconnect) in residential only, including multifamily 310.15 (B) (7) in 2011 nec


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## GREGNC (Nov 13, 2007)

338.4a in the 2011 excludes 334.80
But adds where installed in thermal insulation use
Use 60º rating
So 1/0 alum. Or #2 and leave insulation 
Out between 1 row of ceiling joists:laughing:


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## Hexamexapex (Jun 9, 2012)

Hippie said:


> #2 al has always been good for a 100A service and main feeder (if coming off a disconnect) in residential only, including multifamily 310.15 (B) (7) in 2011 nec


Ah I think I got you now. The 338.4 interior installation stipulation does not apply to main power feeder wires. Only when using SE for branch circuit or interior sub panel feeds does the 60C ampacity provision apply. Or, for example, when we use SE aluminum for range circuit. Sound right now? 

My apologies to GregNC. It appears I have talked out my ass once again.


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## Hippie (May 12, 2011)

The ampacity in 310.15 (B) (7) can only be used only for *residential service conductors*, a 100 amp branch circuit would have to use the standard 60 degree column


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## GREGNC (Nov 13, 2007)

I dont know 338.4 is branch circuits and 
Feeders


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## Hexamexapex (Jun 9, 2012)

GREGNC said:


> I dont know 338.4 is branch circuits and
> Feeders


You know....lol....it does say feeders. The definition of a feeder is the conductors from main power at service to branch circuit overcurrent device. Maybe my original interpretation was correct.


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## Hexamexapex (Jun 9, 2012)

Hippie said:


> The ampacity in 310.15 (B) (7) can only be used only for residential service conductors, a 100 amp branch circuit would have to use the standard 60 degree column


338.10(4) does say "Installation Methods for Branch Circuits and Feeders - Interior Installations"


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## Shockdoc (Mar 4, 2010)

If you were to run 1" ENT would that allow #2 hots per 90c rating?


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## Blue (Nov 28, 2010)

We still use 2008 code here and 310.15 (b)(6) states #2AL , I maybe wrong but I believe you can use 75 deg. Column of 310.16 where it applies such as when terminal lugs are rated as such ( range receps and panels)


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## GREGNC (Nov 13, 2007)

I guess the key is service entrance
Condutor 
Sometimes I make the simple complicated


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## Hexamexapex (Jun 9, 2012)

Blue said:


> We still use 2008 code here and 310.15 (b)(6) states #2AL , I maybe wrong but I believe you can use 75 deg. Column of 310.16 where it applies such as when terminal lugs are rated as such ( range receps and panels)


My problem is 334.80 which tells me the ampacity shall not exceed that of a 60C conductor. 338.4 tells me to use provisions of 334.80. For interior feeder wire. In my case XHHW type SE.


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## Hexamexapex (Jun 9, 2012)

GREGNC said:


> I guess the key is service entrance
> Condutor
> Sometimes I make the simple complicated


Would you agree that XHHW type SE would qualify as a service entrance conductor when applied as a feeder wire to main lug panelboards?


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## Hexamexapex (Jun 9, 2012)

Shockdoc said:


> If you were to run 1" ENT would that allow #2 hots per 90c rating?


If my current analysis is correct I would still be stuck with an 80 amp breaker due to the 60C ampacity requirement. 60C column has me stuck at 75 amps if I were to use #2 aluminum. Again, if I'm interpreting correctly. Trying to hash this out.


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## Dennis Alwon (May 9, 2009)

Hex you are running around like a chicken without a head...:thumbup: Slow down.. Is this se cable carrying the entire load of the actually apartment? If it is feeder or not it qualifies as the main power feed and can use 310.15(B)(6). It is that simple. Some may feel you cannot do that because of the derating but T. 310.15(B)(6) says nothing to that effect.


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## Blue (Nov 28, 2010)

I believe the bottom line is are you using your #2AL as residential service entrance from meter? If so that is fine.


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## GREGNC (Nov 13, 2007)

My take is 310.15b7. Is good regardless 
Of interior instalation because it is 
The service entrance.
If any doubts leave that pocket
Of insulatiom out then there is no
Doubt


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## Dennis Alwon (May 9, 2009)

Blue said:


> I believe the bottom line is are you using your #2AL as residential service entrance from meter? If so that is fine.


I hope it is not service entrance as the disconnect must be installed as near as possible to the point of entry into the building


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## Blue (Nov 28, 2010)

Dennis Alwon said:


> I hope it is not service entrance as the disconnect must be installed as near as possible to the point of entry into the building


OP states his "service entrance cable". So I would think this is what he means . Dennis , do you agree #2AL is OK?


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## Hexamexapex (Jun 9, 2012)

Dennis Alwon said:


> Hex you are running around like a chicken without a head...:thumbup: Slow down.. Is this se cable carrying the entire load of the actually apartment? If it is feeder or not it qualifies as the main power feed and can use 310.15(B)(6). It is that simple. Some may feel you cannot do that because of the derating but T. 310.15(B)(6) says nothing to that effect.


There you are! What took you so long? Lol....I will take yours and everyone's word that table 310.15b6 is what I need. The SE cable does carry the load of entire apartment. We have 8 units and we pull XHHW from each apartment to supply side. So in fact, 3 of those pulls are over 100ft of XHHW. 338.10a4 just throws me off. When it says interior installation for branch circuits and feeders I take the definition of a feeder and apply that to our apartment #2 XHHW service....and so on. What am I missing? Or should I just press the "believe it" button.


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## Hexamexapex (Jun 9, 2012)

Dennis Alwon said:


> I hope it is not service entrance as the disconnect must be installed as near as possible to the point of entry into the building


Disconnects and meters are contained in two "4-pack" enclosures/cutout boxes. Two service lateral conduits are run to appropriate side of apartment building.....from transformer... We build our services....etc.


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## Blue (Nov 28, 2010)

Hexamexapex said:


> There you are! What took you so long? Lol....I will take yours and everyone's word that table 310.15b6 is what I need. The SE cable does carry the load of entire apartment. We have 8 units and we pull XHHW from each apartment to supply side. So in fact, 3 of those pulls are over 100ft of XHHW. 338.10a4 just throws me off. When it says interior installation for branch circuits and feeders I take the definition of a feeder and apply that to our apartment #2 XHHW service....and so on. What am I missing? Or should I just press the "believe it" button.


I would not press that button. Even though I believe I am right means nothing. But it sounds like your ahj is passing it


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## Hexamexapex (Jun 9, 2012)

Blue said:


> I would not press that button. Even though I believe I am right means nothing. But it sounds like your ahj is passing it


He is passing it. The issue is I am studying up to get my LLE, Limited license electrician certification. I'd really like to know the correct NEC answer to this in case I see it in the test. Local jurisdiction doesn't help me in this case..... I need to know what NEC test would say. And is really like to differentiate between what 338, 334, and 310.16 say and what T310.15 is telling me about SE cable.


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## Deep Cover (Dec 8, 2012)

I'm gonna throw another stick into this fire...

I do not believe those SER's are carrying the entire load of the service and as such, you cannot use Table 310.15(B)(7).


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## Hexamexapex (Jun 9, 2012)

Deep Cover said:


> I'm gonna throw another stick into this fire...
> 
> I do not believe those SER's are carrying the entire load of the service and as such, you cannot use Table 310.15(B)(7).


Well they are carrying the entire load for each unit. 8 unit apartment ...8 different SE XHHW cables. 4 into one "4 pack" enclosure and 4 into another. Each enclosure fed from transformer through individual conduit piping.


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## Deep Cover (Dec 8, 2012)

What size service is on the building? I'm pretty sure its not 100A.


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## Deep Cover (Dec 8, 2012)

You guys must do something different there. From what you are saying, you are running two feeds to the same building which wouldn't be allowed by the NEC. How far apart are the meter stacks?


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## Hexamexapex (Jun 9, 2012)

Deep Cover said:


> What size service is on the building? I'm pretty sure its not 100A.


Great question: well the enclosures are designed such that each 100 amp breaker we install is fed from a single termination point. And we install two enclosures....so....


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## Deep Cover (Dec 8, 2012)

I equate this to a 400A residential service feeding two 200A panels.


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## Hexamexapex (Jun 9, 2012)

Deep Cover said:


> I equate this to a 400A residential service feeding two 200A panels.


Meter stacks are side by side. Maybe it's an 800 amp service feeding two 400 amp stacks. Since we have 4 100 amp breakers installed per stack...4 meters per stack. I was told its considered two separate services. Apparently local jurisdiction allows this. But..to my original point...I don't think the ampacity of our service feeder wires, coming from each meter is rated for 100. According to NEC 338, 334.80, and 310.16 we are at 75 amps per feed. ...lol...geez


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## Deep Cover (Dec 8, 2012)

I think you are correct in a round about way.


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## Hexamexapex (Jun 9, 2012)

I think in the end I might not be defining and differentiating a "feeder" and "service entrance" conductor appropriately. In my case, as many of you have alluded to, the #2 XHHW I'm using is defined as service entrance...so table 310.15 is appropriate. 
Now if I was to use my #2 XHHW as a feed to a sub panel ....I think the provisions of 338,334, and table 310.16 come into play.


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## Dennis Alwon (May 9, 2009)

Hexamexapex said:


> I think in the end I might not be defining and differentiating a "feeder" and "service entrance" conductor appropriately. In my case, as many of you have alluded to, the #2 XHHW I'm using is defined as service entrance...so table 310.15 is appropriate.
> Now if I was to use my #2 XHHW as a feed to a sub panel ....I think the provisions of 338,334, and table 310.16 come into play.



The feeder would only be required to follow 310.16 if it did not carry the entire load, otherwise 310.15(B)(6) is appropriate. I really don't know how to say this another way as I have stated it may times in different ways.


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## Hexamexapex (Jun 9, 2012)

Dennis Alwon said:


> The feeder would only be required to follow 310.16 if it did not carry the entire load, otherwise 310.15(B)(6) is appropriate. I really don't know how to say this another way as I have stated it may times in different ways.


You got me with that one. I was getting feeder and service entrance conductors mixed up. Sorry, takes a minute to get my mind wrapped around it sometimes. Lol...over 40 posts...but damnit I finally got it. Thanks again.


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## Blue (Nov 28, 2010)

Are we talking about from the load side of your meter (100 amp main) to each apt?


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## Hexamexapex (Jun 9, 2012)

Hexamexapex said:


> You got me with that one. I was getting feeder and service entrance conductors mixed up. Sorry, takes a minute to get my mind wrapped around it sometimes. Lol...over 40 posts...but damnit I finally got it. Thanks again.


Let me rephrase ....I guess the service entrance conductors could also be considered feeder wire. The big ticket is whether or not the conductors serve as the main power feed or not. Think I got that now.


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## Hexamexapex (Jun 9, 2012)

Blue said:


> Are we talking about from the load side of your meter (100 amp main) to each apt?


Yes. Load side of 100amp main. Now in this installation we have two 4-meter stacks...installed side-by-side. Each meter having its own 100amp disconnect. There is no "main" disconnect for the meter stack enclosures.


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## Hexamexapex (Jun 9, 2012)

This


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## Deep Cover (Dec 8, 2012)

How are those two stacks bonded to each other?


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## Hexamexapex (Jun 9, 2012)

Deep Cover said:


> How are those two stacks bonded to each other?


Funny you should ask. That pic is from a thread I started about a year ago cuz I asked same question. But no they aren't bonded together. Each are grounded to their own respective ground rod. Inspector passes every time. I asked him if we should be at least bonding the two rods. He said nah....lol.


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## Blue (Nov 28, 2010)

That is what I thought. I was confused after all the posts whether or not you meant the lateral to the banks or feeding the apt (units) panel


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## Deep Cover (Dec 8, 2012)

I don't see how this is a compliant install.

Two of the same type of service to a building
Over 6 discos
SER running length-ways in the brick
(I contend) SER not sized appropiately
Possible bonding issues

(I thought I remembered something like this a while back)


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## Blue (Nov 28, 2010)

Deep Cover said:


> I don't see how this is a compliant install.
> 
> Two of the same type of service to a building
> Over 6 discos
> ...


Not to get off topic but every time I read one of your posts I hear Sheldon's voice LoL . Great icon


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## Dennis Alwon (May 9, 2009)

There are two service laterals thus they are 2 services. Each service is allowed 6 disconnects-- some would say 36- 6 for each apt. Anyway I see it as compliant and they could have used the same rods.


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## Hexamexapex (Jun 9, 2012)

Deep Cover said:


> I don't see how this is a compliant install.
> 
> Two of the same type of service to a building
> Over 6 discos
> ...


1.) AHJ considers this two separate services and this application falls under exception in 230.40.
2.) Conduit from city main run "counter" to how are stacks need to be placed. Had to do what we had to do with knocking out brick. We passed....shoddy I know.
3.) SER carrying full load of each unit so 310.15 is ok?
4.) AHJ says two rods need not be bonded.


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## chicken steve (Mar 22, 2011)

Deep Cover said:


> I don't see how this is a compliant install.
> 
> 
> 
> ...


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## Dennis Alwon (May 9, 2009)

Hexamexapex said:


> 1.) AHJ considers this two separate services and this application falls under exception in 230.40.
> 2.) Conduit from city main run "counter" to how are stacks need to be placed. Had to do what we had to do with knocking out brick. We passed....shoddy I know.
> 3.) SER carrying full load of each unit so 310.15 is ok?
> 4.) AHJ says two rods need not be bonded.


I agree but I would bond the rods together simply because the code probably requires 2 rods and I am sure they don't meet the 25 ohms... I bet they aren't at least 6' apart either though.


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## Hexamexapex (Jun 9, 2012)

Dennis Alwon said:


> I agree but I would bond the rods together simply because the code probably requires 2 rods and I am sure they don't meet the 25 ohms... I bet they aren't at least 6' apart either though.


We did separate them by six feet. I the boss man why we weren't bonding the two rods. His response was something along the lines of it being two separate services so bonding wasn't necessary. I didn't even show him the codes in the book that say whether separate services or not all equipment grouped together need be bonded. Busy pullin wire, else I'd find that code. Been found before....250?


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## Dennis Alwon (May 9, 2009)

Hexamexapex said:


> We did separate them by six feet. I the boss man why we weren't bonding the two rods. His response was something along the lines of it being two separate services so bonding wasn't necessary. I didn't even show him the codes in the book that say whether separate services or not all equipment grouped together need be bonded. Busy pullin wire, else I'd find that code. Been found before....250?



I don't believe the rods need to be bonded together if they are different service but each service needs to meet the 25 ohm requirement or 2 rods must be used... 250.56. Since there are 2 rods a bonding jumper between them would satisfy the requirements for both services otherwise each service would need 2 rods. Most areas cannot show 25 ohms with one rod- maybe your area is one of the lucky ones or the inspectors are not enforcing it.


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## Hexamexapex (Jun 9, 2012)

Dennis Alwon said:


> I don't believe the rods need to be bonded together if they are different service but each service needs to meet the 25 ohm requirement or 2 rods must be used... 250.56. Since there are 2 rods a bonding jumper between them would satisfy the requirements for both services otherwise each service would need 2 rods. Most areas cannot show 25 ohms with one rod- maybe your area is one of the lucky ones or the inspectors are not enforcing it.


Ah.... Once again.....you clarify.


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## Hexamexapex (Jun 9, 2012)

Dennis Alwon said:


> I don't believe the rods need to be bonded together if they are different service but each service needs to meet the 25 ohm requirement or 2 rods must be used... 250.56. Since there are 2 rods a bonding jumper between them would satisfy the requirements for both services otherwise each service would need 2 rods. Most areas cannot show 25 ohms with one rod- maybe your area is one of the lucky ones or the inspectors are not enforcing it.


I was thinking the two enclosures needed to be bonded together and tying the rods together would satisfy that requirement. Each enclosure has its own grounding conductor going to each rod.


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## chicken steve (Mar 22, 2011)

the Grod can't be the _only_ GEC Hex....

~CS~


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## Hexamexapex (Jun 9, 2012)

chicken steve said:


> the Grod can't be the only GEC Hex....
> 
> ~CS~


Well.....in this application it is I guess. AHJ approves it. One Grod per service/cutout box. Doesn't test for 25 ohms and he doesn't require the two be tied together. But I understand what ur saying...


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