Service cable SEU & SER

[augie47]

Your point directly nails the argumentative nature of this issue.
If, as you say, you want to maintain the same ampacity, then you would need to increase the interior SE to attain the same ampacity, however, literally 215.2 would allow the smaller cable.

The 338.10 vs 215.2/310.16 situation, unfortunately, is interpreted differently in different areas.

 

[Dennis Alwon]

Your point directly nails the argumentative nature of this issue.
If, as you say, you want to maintain the same ampacity, then you would need to increase the interior SE to attain the same ampacity, however, literally 215.2 would allow the smaller cable.

The 338.10 vs 215.2/310.16 situation, unfortunately, is interpreted differently in different areas.

Yes, I agree with you and I responded to this differently just before you posted.

 

[pete m.]

the language of 334.80 did not significantly change in the ROP,

There is a significant change to 338.10(B)(4)(a) that has been proposed vs. what is currently in place:

(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. [ROP
7-133]
Where installed in thermal insulation, the ampacity shall be
in accordance with the 60?C (140?F) conductor temperature
rating. The 90?C (194?F) rating shall be permitted to be
used for ampacity adjustment and correction purposes, provided
the final derated ampacity does not exceed that for a
60?C (140?F) rated conductor. [ROP 7-133]

Pete

 

[cpal]

There is a significant change to 338.10(B)(4)(a) that has been proposed vs. what is currently in placeete

Agreed . But that is not a change to the language of 334.80.

 

[jbelectric777]

The load calculated was in the low 190's area, I needed a conductor good for at least (i think it was 193.7 so say 194) so the 194 calc was ok and the architect specified 3/0 Cu THHN/THWN so first off the bat when i saw the ser i kinda knew it before i saw what they did. The only other thing I wanted to add was even in a house, your first feeder or service can be 4/0 al but any sub panels after that say for a 100 amp, the #2 al ser can only have ocp maxed @ 90 amps because you take that from 310.16 not the note 8 for dwellings and aluminum. I also agree with the poster who said an office wont really see that much load anyway, maybe some day they'll change that note 8 around to include commercial occupancies not more than______ square feet. so fill in the blank, meaning note 8 would or could apply to small offices not more than 5000 square feet. I mean a home many times is used as a small home office right? and how many times do you think an existing building was changed use and knowone picked up on it. Because if you think about it a change of use actually allows the UCC to start from scratch but they dont, they send a property inspector out and all he looks for are just to make sure on gfi's and smoke/carb detectors...... i normally let that petty crap alone ya know, ok all bozz scaggs lido shuffle came on im gonna turn up the tunes!!!!!

 

[cpal]

#2 al ser can only have ocp maxed @ 90 amps because you take that from 310.16 not the note 8 for dwellings QUOTE]


just curious
what year code book are you working with??

 

[ceb58]

All I know is I priced 3/0 cu ser. $13.00 per ft. I have been looking for 250mcm se or ser al supplier said its not being made. Also the lugs on a 200 amp panel are not rated for 250mcm

 

[Dennis Alwon]

I have been looking for 250mcm se or ser al supplier said its not being made. Also the lugs on a 200 amp panel are not rated for 250mcm

250 mcm ser is being made and I believe a 200 amp panel will accept 250 MCM but not 300MCM. If you do a 400 amp service 250 MCM al is not enough if you have to use 60C. You must use 300 MCM and the lugs will not accommodate that.

 

[M. D.]

I know that Dennis brought this up way back and I did again some time after ,...I'm curious if anyone has any info in regard to this as it relates to this topic. Has U.L. changed the way meter sockets are to be listed ??


http://www.iaei.org/magazine/?p=419

Requirements for wire bending space and the conductor size a terminal is rated to terminate are reduced to account for the reduced size conductor. For example: NEC Table 310.16 would require 3/0 Copper for 200 A service, while UL 414 would allow 2/0 if marked for this application [which is in agreement with conductor ampacities provided in NEC Table 310.15(B)(6)]. These meter sockets have not been evaluated for applications that go beyond this limitation.

 

[elohr46]

250 mcm ser is being made and I believe a 200 amp panel will accept 250 MCM but not 300MCM. If you do a 400 amp service 250 MCM al is not enough if you have to use 60C. You must use 300 MCM and the lugs will not accommodate that.

My area adopts the 2008 code on Jan. 1st, so your saying for a 400 amp service with two 200 amp panels the service cable needs to be 300kcmil to each panel.

 

[Dennis Alwon]

My area adopts the 2008 code on Jan. 1st, so your saying for a 400 amp service with two 200 amp panels the service cable needs to be 300kcmil to each panel.

Yes, if you are using se cable and it enters the interior of the house as stated in 338.10(B)(4)(a)

 

[M. D.]

My area adopts the 2008 code on Jan. 1st, so your saying for a 400 amp service with two 200 amp panels the service cable needs to be 300kcmil to each panel.

Right,.. this is why I brought this up again ,..

Requirements for wire bending space and the conductor size a terminal is rated to terminate are reduced to account for the reduced size conductor. For example: NEC Table 310.16 would require 3/0 Copper for 200 A service, while UL 414 would allow 2/0 if marked for this application [which is in agreement with conductor ampacities provided in NEC Table 310.15(B)(6)]. These meter sockets have not been evaluated for applications that go beyond this limitation.[/QUOTE]

So if the equipment is marked as for residential use ,.. I guess your screwed ,.. unless there has been a change.

 

[elohr46]

Yes, if you are using se cable and it enters the interior of the house as stated in 338.10(B)(4)(a)

Ok, but you stated earlier that 300kcmil will not fit in the lugs of a 200a cb. How do we get around that?

 

[Dennis Alwon]

Ok, but you stated earlier that 300kcmil will not fit in the lugs of a 200a cb. How do we get around that?

I didn't say I have the answers I just stated what the code requires. It is a problem. One inspection dept is allowing the use of 250Kcm but I always use copper in conduit and avoid the issue altogether. Aluminum in conduit would work fine also. In conduit you would only need 4/0 alum as long as the load on either panel is not more than 180 amps.

 

[elohr46]

I didn't say I have the answers I just stated what the code requires. It is a problem. One inspection dept is allowing the use of 250Kcm but I always use copper in conduit and avoid the issue altogether. Aluminum in conduit would work fine also. In conduit you would only need 4/0 alum as long as the load on either panel is not more than 180 amps.

I see, it is a problem. Could the main cb in each panel be changed to a 175 to correct it if for 250kcmil SE cable? Or will that just be the same problem with 250 not fitting into a 175a cb? I should check the lugs first.

 

[Dennis Alwon]

I see, it is a problem. Could the main cb in each panel be changed to a 175 to correct it if for 250kcmil SE cable? Or will that just be the same problem with 250 not fitting into a 175a cb? I should check the lugs first.

I had an EC friend do exactly that but he used 150 amp breakers since they were more available and cheaper. The load apparently was under 300 amps so...

 

[augie47]

In that the 60? rating is enforced in this area, 300 kcmil is not uncommon and there are loadcenters available with MLO and M Breakers that will accept that size. I rather not state manufacturers so as not to exclude anyone, but they are readily available.

 

[iwire]

If you are using the 2008 NEC then SE cable is limited to the 60 degree column of 310.16 so therefore 4/0 AL SER is good for 150 amps.

Chris

334.80 does not apply to SE service conductors or SE feeders run outside.

 

[pete m.]

Agreed . But that is not a change to the language of 334.80.

The point I was attempting to make is that if the proposed change to 338.10(B)(4)(a) remains unchanged through the comment stages then it will effectively remove the 60 degree limitation imposed by 334.80 for SE/SER cable used as feeder or branch circuit wiring on the interior of the structure. Unless, of course, it is ran in thermal insulation.

Unless I'm missing something....

Pete