2-2-2-4 SER Amperage

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  #1  
Old 02-03-08, 12:27 AM
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2-2-2-4 SER Amperage

I've got a sub-panel about 10' from my main panel. I've wired it up using 2-2-2-4 SER. From a strict code interpretation, should this sub-panel be fused at 90 amps, or is it typical to just go with 100 amps? I will ultimately ask my inspector, but hoped I might arm myself with information before talking to him. Thanks!
 
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Old 02-03-08, 07:47 AM
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if i understand your question correctly, either you or someone else is interpreting the code wrong. this would fall under 310.15 b 6 and the conductor would be rated at 125 amps. what size is your main?
Originally Posted by Stormy2084 View Post
I've got a sub-panel about 10' from my main panel. I've wired it up using 2-2-2-4 SER. From a strict code interpretation, should this sub-panel be fused at 90 amps, or is it typical to just go with 100 amps? I will ultimately ask my inspector, but hoped I might arm myself with information before talking to him. Thanks!
 
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Old 02-03-08, 09:30 AM
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Originally Posted by sparky480 View Post
if i understand your question correctly, either you or someone else is interpreting the code wrong. this would fall under 310.15 b 6 and the conductor would be rated at 125 amps. what size is your main?
My main is 200 amps. I was looking at (table 310.16) which states 75, 90, 100 amps at 60, 75, 90 degrees respectively. My panel (QO) has a sticker stating "Suitable for use with 75 degree copper or aluminum main conductors." As I understand it, this means I have to look at the 75 degrees column and this, 90 amps? This is aluminum - I guess I didn't state that before. My NEC book is from 2002 - that's another reason I'm asking here. Thanks!
 
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Old 02-03-08, 10:24 AM
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sir, when i stated that you or someone else was interpreting the code incorrectly, because by reading your first question i sensed you were in 310.16. again look at the article and table i stated earlier for your answer.tyat (table 310.16) which states 75, 90, 100 amps at 60, 75, 90 degrees respectively. My panel (QO) has a sticker stating "Suitable for use with 75 degree copper or aluminum main conductors." As I understand it, this means I have to look at the 75 degrees column and this, 90 amps? This is aluminum - I guess I didn't state that before. My NEC book is from 2002 - that's another reason I'm asking here. Thanks![/QUOTE]
 
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Old 02-03-08, 01:35 PM
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Thanks for your patience with me Sparky! I've re-read and it makes sense now. My confusion was that there was no SER listed (just SE) and I guess I thought that since it was bundled it would fall under another table.
 
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Old 02-03-08, 04:38 PM
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ser= service entrance rated same as se= service entrance
Originally Posted by Stormy2084 View Post
Thanks for your patience with me Sparky! I've re-read and it makes sense now. My confusion was that there was no SER listed (just SE) and I guess I thought that since it was bundled it would fall under another table.
 
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Old 02-03-08, 04:44 PM
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The 2-2-2-4 SER is rated in two ways and the NEC is pretty spefic on this one and this is a common mistake if not carefull with this part the service entrance and feeder both are not the same on amparage rating.

to use to feed the subfeeder it will only allowed to 90 amp but if this was a service entrance yeah it can go 100 amp.

so just want to head up with this.

Merci, Marc
 
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Old 02-03-08, 06:19 PM
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not trying to light up debate, but you can also use the 125 amp rating due to still being a panelboard ty p.s. read code article given
Originally Posted by french277V View Post
The 2-2-2-4 SER is rated in two ways and the NEC is pretty spefic on this one and this is a common mistake if not carefull with this part the service entrance and feeder both are not the same on amparage rating.

to use to feed the subfeeder it will only allowed to 90 amp but if this was a service entrance yeah it can go 100 amp.

so just want to head up with this.

Merci, Marc
 
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Old 02-03-08, 09:16 PM
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Originally Posted by sparky480 View Post
not trying to light up debate, but you can also use the 125 amp rating due to still being a panelboard ty p.s. read code article given
I understand what you are trying to say but the section cited states:service entrance conductors,service lateral conductors,and feeder conductors that serve as the main power feeder.

It does go on to state (and this is where the confusion comes in to play):for application of this section, the main power feeder shall be the feeder between the main disconnect and the lighting or power panelboards.

Obviously, you read this as since it is feeding a panelboard that it is allowed to be used at the 125 amp rating but you are missing the part about from the main service disconnect to those panelboards noted.

This is not going from the main disconnect to one of the boards noted. It is going from a breaker within the main panel to a subpanel. It is NOT the main power feeder. Now, if there was a main disconnect that was not the main of a panel and the feeders then went to some subsequent panelboards, I could agree with you but it is not set up like that.


Now, you may convince an inspector to accept this section as allowing such use but this section does not actually permit the 125 amp rating of #2 aluminum.

So, since 310.16 comes back in to play, you are limited to 90 amp breaker.

Oh, and by the way, I was using your 125 amp claim but if you will look at the table 310.15(B)(6) again, you should note that #2 aluminum is still only rated at 100 amps when this section does come in to play.

the 125 amp rating is for copper wire.
 
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Old 02-03-08, 09:59 PM
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As far i was mention the 2-2-2-4 SER cable i should mention Alum wire because i know it sometime come in copper verison as well so what i qouted above with the amp capcity. that is correct for Alum verison but copper go higher amp rating. sorry about that.

Merci, Marc
 
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Old 02-04-08, 04:44 PM
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post #3. apparently sparky 480 missed it as well.
 
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Old 02-04-08, 06:29 PM
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ty nap for info., i actually did what i mostly do not do and stepped outside my element(comm./ind. here) , thus maybe being wrong in my interpretation.
Originally Posted by nap View Post
post #3. apparently sparky 480 missed it as well.
 
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Old 02-06-08, 05:40 AM
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And the inspector says... 90 amps. I brought up some of the points made in this (and another thread I found here). He said that some inspectors still allow a 100 amp breaker to be used on subpanels, but his interpretation is that you have to go to the 60 degree column and use 90 amps.

I also spoke to my electrician and he noted that the inspector in the county next to ours he can still get by with 100, but the inspector here requires 90. He also noted that his own interpretation is 90.

Anyhow, I asked the original question hoping to save a few bucks by using a 100a breaker I had already purchased. I guess I'll be getting a 90 now. Thanks again for all the input.
 
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Old 02-06-08, 07:05 AM
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Inspectors sometimes allow 310.15(B)(6) when the subpanel is in a separate building. I've never heard of an inspector allowing it with the subpanel is in the same building. I did not detect in this thread mention of whether or not the subpanel was in a separate structure.
 
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Old 02-06-08, 03:30 PM
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so, has anybody taken a look at the '08 code and the changes to this section?

It removes the confusion of the possibility of utilizing this section to include a subpanel.

It is no longer ambiguous nor is it allowed (in feeding a subpanel).
 
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Old 02-06-08, 04:22 PM
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Nap .,, I am not done reading with the 08 code cycle yet but there are quite few change along the way [beep].

but to related to this question i will reply later tonite once i get correct statement and post it here.

yeah they did change some related to the feeder circuit.

Merci, Marc
 
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