Residential question.....

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c2500

Senior Member
Location
South Carolina
This is new construction. You are operateing under the 2003 IRC which I believe is the 2002 NEC.

You have a 200 amp Siemens load center that is used as a sub panel. You need to feed a 100 amp Siemens sub panel that is located approximately 62 feet away.

1. If you were to use copper, what type/size would you run?
2. If you were to run aluminum, what type/size would you run?

I am curious to see if you/your jurisdiction would require the same as mine.

I'll post what mine is later (for those that are interested anyway.)

Thanks,

c2500
 
stickboy1375

stickboy1375

Senior Member
Location
Litchfield, CT
electricalperson said:
number 2 SER aluminum or number 3 SER or romex copper
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Number 2 Al. SER is no good for 100 amps.

I would never need 100 amp sub-panel so I just install #2 SER AL. and use a 90 amp breaker... :) I would use #1 SER AL, if I actually did need 100 amps.
 
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c2500

Senior Member
Location
South Carolina
stickboy1375 said:
I would use #1 SER AL, if I actually did need 100 amps.
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Yep, thats how it is done in the city here. Amazingly though I still think the county lets you get away with #2SER. I would have run a 90amp on this one but by customer has added just enough things I feel 100 is a safer bet. Now I have to find some #1 SER...my usual supply house and the big boxes don't carry any. I also thought the $6.65 a foot for the #3-3 with ground NM was a bit pricey. (Who knows these days?) So I will start calling around tommorow.

c2500
 
Dennis Alwon

Dennis Alwon

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Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
stickboy1375 said:
Number 2 Al. SER is no good for 100 amps.

I would never need 100 amp sub-panel so I just install #2 SER AL. and use a 90 amp breaker... :) I would use #1 SER AL, if I actually did need 100 amps.
Click to expand...

Come 2008 code -- if Connecticut ever catches up with the rest of the world-- that #2 ser alum will only be good for 75 amps-- 80 amp breaker depending...
 
wbalsam1

wbalsam1

Senior Member
Location
Upper Jay, NY
c2500 said:
This is new construction. You are operateing under the 2003 IRC which I believe is the 2002 NEC.

You have a 200 amp Siemens load center that is used as a sub panel. You need to feed a 100 amp Siemens sub panel that is located approximately 62 feet away.

1. If you were to use copper, what type/size would you run?
2. If you were to run aluminum, what type/size would you run?

I am curious to see if you/your jurisdiction would require the same as mine.

I'll post what mine is later (for those that are interested anyway.)

Thanks,

c2500
Click to expand...

Table 3503.1 requires #4 cu or @2 alu. :smile:
 
infinity

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
SE cable now requires us to use it's 60 degree rating. That translates to #1/0 AL or #2 Cu for 100 amps.
 
wbalsam1

wbalsam1

Senior Member
Location
Upper Jay, NY
infinity said:
SE cable now requires us to use it's 60 degree rating. That translates to #1/0 AL or #2 Cu for 100 amps.
Click to expand...

I think the catch here is that the question is referring to the IRC. Both the 2003 and 2006 IRC at Table 3503.1 permit #4 cu and #2 alu for 100 ampere se conductors and/or feeders. :smile:

CORRECTION: The Table I mentioned above (3503.1) only applies to feeders that serve the entire dwelling. Table 3605.1 applies to remote panelboards within the dwelling. This Table requires #3 cu for 100 amps or #1 alu. (assuming 75C). Or as has accurately been pointed out, 1/0 alu or #2 cu. :smile:
 
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S

satcom

Senior Member
infinity said:
SE cable now requires us to use it's 60 degree rating. That translates to #1/0 AL or #2 Cu for 100 amps.
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Are the connections rated for 60 or is the cable TW in a jacket?
 
Dennis Alwon

Dennis Alwon

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Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
satcom said:
Are the connections rated for 60 or is the cable TW in a jacket?
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SE cable when used in he interior of the house for feeders or branch circuits is now(2008 code) rated the same as NM cable. The wiring is still 90C but you must use connections at 60 C.
 
S

satcom

Senior Member
Dennis Alwon said:
SE cable when used in he interior of the house for feeders or branch circuits is now(2008 code) rated the same as NM cable. The wiring is still 90C but you must use connections at 60 C.
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Hi Dennis, were not 2008 yet, and the way it looks, if it is like every other cycle we will be in 2008 sometime in 2010 or later. Yes the treating like TW, or NM will make a difference.

One thing we noticed is when some commercial jobs were done some EC's were using the residential tables for commercial, it should get intresting.
 
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stickboy1375

stickboy1375

Senior Member
Location
Litchfield, CT
satcom said:
Hi Dennis, were not 2008 yet, and the way it looks, if it is like every other cycle we will be in 2008 sometime in 2010 or later. Yes the treating like TW, or NM will make a difference.

One thing we noticed is when some commercial jobs were done some EC's were using the residential tables for commercial, it should get intresting.
Click to expand...


It will get VERY interesting, of course only depending on the inspectors knowledge.
 
Dennis Alwon

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
I just installed 2 40 circuit sub panels fed with 100 amp breakers. The load will probably be less than 75 amps total most of the time.

Oh yeah one panel is totally full while the other has about 3 spares.
 
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macmikeman

Senior Member
Location
Planet macmikeman
c2500 said:
Yep, thats how it is done in the city here. Amazingly though I still think the county lets you get away with #2SER.
c2500
Click to expand...

I'm not so sure about the amazing part. Where I am at it has been done like that for a very long long time. Yes I know it does not meet 310-15 (B)(2), but "amazingly" it does not seem to cause much problems or stir when #2 alum ser is used for a subpanel feeder around here. Counter desk guy's look at me like I'm from outer space whenever I ask for a 90 amp breaker. (special order). Most times I just run 1/0 ser and put a 100 on it, its stocked localy, but #1 alum ser isn't.
 
stickboy1375

stickboy1375

Senior Member
Location
Litchfield, CT
macmikeman said:
I'm not so sure about the amazing part. Where I am at it has been done like that for a very long long time. Yes I know it does not meet 310-15 (B)(2), but "amazingly" it does not seem to cause much problems or stir when #2 alum ser is used for a subpanel feeder around here. Counter desk guy's look at me like I'm from outer space whenever I ask for a 90 amp breaker. (special order). Most times I just run 1/0 ser and put a 100 on it, its stocked localy, but #1 alum ser isn't.
Click to expand...


Its the same here, every sub-panel I see has #2 SER backed with a 100 amp breaker.
 
C

c2500

Senior Member
Location
South Carolina
macmikeman said:
. Counter desk guy's look at me like I'm from outer space whenever I ask for a 90 amp breaker. (special order). .
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When I did my own house...it was around 4 years ago I was caught on the #2 SER. I went to the supply house and got a 90 amp breaker. The counter guy ask what was going on, because suddenly the 90's that had not been sold in years were now being sold. I assume the inspectors had a class or something and this violation was a new one for them to catch.

c2500
 
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