sub panel in attic

[jetlag]

Thanks dennis

Thanks dennis

Jetlag, for a residence #2 aluminum is legal for 100 amps based on T.310.15(B)(6). This is why the big boxes carry it. I don't think they ever caught up to the fact that now as a feeder se xcable is rated 60c. The fact is that this does not affect USE cable which still has the 90C but must be used at 75C.

I am not sure what you don't understand about 90C termnals because there are very few terminals out there that are rated 90C- just check your equipment.

You mention mobile home UG feeders- USE #2 aluminum is perfectly okay for an UG feeder to the home at 100 amps. Maybe I am missing your point.

You came to rescue again, the other thread was the commercial tap feeder. So code makes exception for residence service conductor. I notice on T.310.15 b 6 at top use which is 75 only rates 90a but is listed with use2 which is 90 c and 100 . So in other words the 90a rate is enough for service of 100 amp. I remember now you get to go one size down on res service. I forgot because dont figure the size any more , 2 is 100 and 4/0 is 200. Are you sure about the se infinity said can use 2 se for service also

 

[Dennis Alwon]

You can use #2 seu cable for service but if it is feeder and doesn't carry the entire load of the dwelling and is installed indoors then you must use 310.16 which means SER cable would be rated at 60C. In this case 4/0 alumin is rated only at 150 amps.

There has been a change in 2011. Basically if the se cable is installed in insulation then it must be rated 60C

338.10(4) Installation Methods for Branch Circuits and Feeders.
(a) Interior Installations. In addition to the provisions of this article, Type SE service-entrance cable used for interior wiring shall comply with the installation requirements of Part II of Article 334, excluding 334.80.
Where installed in thermal insulation, the ampacity shall be in accordance with the 60?C (140?F) conductor temperature rating. The maximum conductor temperature rating shall be permitted to be used for ampacity adjustment and correction purposes, if the final derated ampacity does not exceed that for a 60?C (140?F) rated conductor.

 

[Dennis Alwon]

At 40?C it trips at the handle rating. At 60?C it looks like it would trip at about 17 amps and at -10?C at about 27 amps.

Sorry I meant at 60C-- Doesn't seem like a big issue does it. 60C/ 140F

 

[jetlag]

Thanks dennis

Thanks dennis

You can use #2 seu cable for service but if it is feeder and doesn't carry the entire load of the dwelling and is installed indoors then you must use 310.16 which means SER cable would be rated at 60C. In this case 4/0 alumin is rated only at 150 amps.

There has been a change in 2011. Basically if the se cable is installed in insulation then it must be rated 60C

You are the code wizzard. I remember it all now except never knew about the derate # 2 ser to 75 amp for interior feeder. Thats probably why big blue quit stocking it , you never see a new 100 service any more with an outside disconnect and it wont pass 100 a for inside feeder to sub. I do 100 a all the time on mobile home with ug when home is relocated. I had a job with 200 a outside disconnect , the job was done by someome without a permit and I was called in, In the 200 amp disc they had 2 100 breakers , right beside the main disc they mounted a 100 amp sub the other 100 breaker feed another 100 amp sub inside . The only reason that part was flagged is they only used 3 wire for feeder . I put 4 wire back #2 ser. it still servered the main house load but not on same feeder, can the ser still rated 100 that way ? it did not get flagged. If they had used the couple of spaces left on the 200 main to run a branch circuit would that have changed everything since the two 100 a no longer carried entire house.

 

[glene77is]

Square D document shows the trip points of their breakers

Thanks for the URL. Interesting.
One time I used a sheet metal cover on a utility room door
to keep the circuit breakers cool enough.
Have always wondered what the maker said about their CB.

 

[acrwc10]

Well when the room gets finished the back side of panel will still be in the attic heat and I dont like that much on my own house . But everone gave me a great idea I think i have room by the entrance door for panel to go in wall between attic and bedroom so only front side of panel will be in attic.. I wish I had another place for panel so not bring inspectors attention to the future attic room , I dont have to cut the door thru now . How bad is it for a panel to be on a master bedroom wall ?

Why would you want to hide from the inspector ? If the room being finished is going to be a violation the question you need to ask is, "why would this be a violation?" They don't just make the code up for fun, there is probably an egress or other safety issue. You have to follow this threw to its logical end, if the room is a violation and you wire it, it won't get inspected. If it isn't inspected you have created a violation, now if some thing happens (like a fire) you are going to be called to answer for your work. Even if it wasn't the cause you may still wind up in court. Not where I want to be.
When you have to worry about hiding something from the inspector, you have a problem that you need to deal with.

 

[jetlag]

Why would you want to hide from the inspector ? If the room being finished is going to be a violation the question you need to ask is, "why would this be a violation?" They don't just make the code up for fun, there is probably an egress or other safety issue. You have to follow this threw to its logical end, if the room is a violation and you wire it, it won't get inspected. If it isn't inspected you have created a violation, now if some thing happens (like a fire) you are going to be called to answer for your work. Even if it wasn't the cause you may still wind up in court. Not where I want to be.
When you have to worry about hiding something from the inspector, you have a problem that you need to deal with.

There is not enough room to go into detail on every thing on post . If I had know I would get a lecture I would have. I went to very much pain and expense to be sure the attic space would meet all code requirements so that it could be converted to living space in the future. It has the required sq. ft . ceiling height , load bearing , and also for bed room as I stated is has required egress windows and exit. I am triyng very hard to get ready for a rough in inspection with wiring, plumbing ,heat and air ducts. I just want to let the attic count as light attic storage right now with a scuddle hole from floor below. If cut the door now and install the sub panel I will have to rough all that in now to. I may never get around to the attic but if I do I assure you it will pass inspection , I am not trying to hide anything, I just asked how bad would it be for sub panel to be in master bedroom so I wouldnt not have to go over the entire attic project with the inspector right now. And he might require it to be finished out if I install the sub panel in there. I dont think I could be hiding an attic space from inspector when there is no ceiling below it all he has to do is look up.

 

[mcclary's electrical]

Crazy talk.

Agreed. Please edit to add "his typical"

 

[acrwc10]

240.24(A) Overcurrent devices shall be readily accessible.

So if you can open the door walk in and there it is, it works. If you need a ladder, no good.

 

[jetlag]

240.24(A) Overcurrent devices shall be readily accessible.

So if you can open the door walk in and there it is, it works. If you need a ladder, no good.

I wasnt planning on installing the panel unless I installed the door.
I wasnt planning on roughing the wiring unless I install the door

 

[Cavie]

I wasnt planning on installing the panel unless I installed the door.
I wasnt planning on roughing the wiring unless I install the door

Just run the wire to a j-box and call it future. Don't land it on a breaker in the main panel and there will be no issues. I always ran a 3 wire 12 and a 3 wire 14 to the attics of my jobs for future access.

 

[Dennis Alwon]

Just run the wire to a j-box and call it future. Don't land it on a breaker in the main panel and there will be no issues. I always ran a 3 wire 12 and a 3 wire 14 to the attics of my jobs for future access.

Yeah, and then they add a 5KW heat pump up there. Then what? I would rather have plenty of future possibilities. I often run a pipe from attic to crawl for this reason-- new construction of course.

 

[Cavie]

Yeah, and then they add a 5KW heat pump up there. Then what? I would rather have plenty of future possibilities. I often run a pipe from attic to crawl for this reason-- new construction of course.

Nothing stoping you from running large enought wire for future sub panel.

 

[jetlag]

thanks cavie

thanks cavie

Just run the wire to a j-box and call it future. Don't land it on a breaker in the main panel and there will be no issues. I always ran a 3 wire 12 and a 3 wire 14 to the attics of my jobs for future access.

I never did like multi wire very much but might since it is future anyway, If not will leave 2 12/2 and 1 14/2 .

 

[jetlag]

thanks cavie

thanks cavie

Nothing stoping you from running large enought wire for future sub panel.

that might be best since this thread was about the sub panel, ser alum is not that expensive. I guess i cant use the #2 ser anymore since rated 75 amp . will need 1 or 1/0 to get 90 100 amp

 

[Dennis Alwon]

that might be best since this thread was about the sub panel, ser alum is not that expensive. I guess i cant use the #2 ser anymore since rated 75 amp . will need 1 or 1/0 to get 90 100 amp

Why would you need a 100 amp panel in an attic. A bit overkill, IMO. #1 alum. is good for 85 amps so you can put it on a 90 amp breaker if your calculated load is not over 85 amps. If you want 100 amps then you need 1/0 alum.

 

[goldstar]

Why would you need a 100 amp panel in an attic. A bit overkill, IMO.

No question about it. But it's always better to have more capability than less.

#1 alum. is good for 85 amps so you can put it on a 90 amp breaker if your calculated load is not over 85 amps.

Not if you're using the 60 degree column .

If you want 100 amps then you need 1/0 alum.

Correct.

 

[Dennis Alwon]

Not if you're using the 60 degree column .

I disagree #1 alum is good for 85 amps at 60C as I stated above

 

[jetlag]

Why would you need a 100 amp panel in an attic. A bit overkill, IMO. #1 alum. is good for 85 amps so you can put it on a 90 amp breaker if your calculated load is not over 85 amps. If you want 100 amps then you need 1/0 alum.

Im getting confused , the 100 amp was when I was thinking about installing the sub panel now and it would have inside hot tub and 5 kw air handler in master bed, counter top recpts in kitchenett in attic and all gen purpose light and rec for master bed and bath and attic. if I just leave the attic for future the 75 a 2 ser will be okay .. I still might go with the sub panel now but if not in attic would have to go on master bed room wall, would that hurt value of house to have sub panel on master bedroom wall ?

 

[LEO2854]

Im getting confused , the 100 amp was when I was thinking about installing the sub panel now and it would have inside hot tub and 5 kw air handler in master bed, counter top recpts in kitchenett in attic and all gen purpose light and rec for master bed and bath and attic. if I just leave the attic for future the 75 a 2 ser will be okay .. I still might go with the sub panel now but if not in attic would have to go on master bed room wall, would that hurt value of house to have sub panel on master bedroom wall ?

Why would you put the sub panel in the master bedroom if you have room in the attic?