Service entry code question.

Reply

  #1  
Old 02-02-10, 08:31 PM
Niadh's Avatar
Member
Thread Starter
Join Date: Aug 2006
Location: USA
Posts: 223
Received 0 Votes on 0 Posts
Service entry code question.

I've been gathering a few quotes on getting a new service drop and meter socket put in and one of the electricians told me that you could not run SE cable out the back of the meter socket, down a stud bay and into the basement. This is the way the current feed is ran. He said it had to go down the outside of the house in a conduit to the cinder blocks and then enter the house threw the block. To do this requires the meter socket to be relocated on a different wall moving the breaker box and consequently a much higher bill. The other two electricians didn't seem to have a problem running it threw the stud bay as it is now.

What are the rules governing running of SE? What section of code covers it? I found 230.6 which talks about when the conductor is considered outside the building but doesn't address raceways that are not concrete and 230.7 which tells me nothing else can be in that raceway but the SE and bonds/grounds. I skimmed all of 230 but didn't find anything obvious so I'm asking you guys first before deciding which route to go. No need to worry though since permits WILL be pulled. I made that obvious to all three.

Thanks for the help.
 
Sponsored Links
  #2  
Old 02-02-10, 09:11 PM
CasualJoe's Avatar
Member
Join Date: Jan 2010
Location: United States
Posts: 10,645
Received 85 Votes on 75 Posts
Originally Posted by Niadh View Post
I've been gathering a few quotes on getting a new service drop and meter socket put in and one of the electricians told me that you could not run SE cable out the back of the meter socket, down a stud bay and into the basement. This is the way the current feed is ran. He said it had to go down the outside of the house in a conduit to the cinder blocks and then enter the house threw the block. To do this requires the meter socket to be relocated on a different wall moving the breaker box and consequently a much higher bill. The other two electricians didn't seem to have a problem running it threw the stud bay as it is now.

What are the rules governing running of SE? What section of code covers it? I found 230.6 which talks about when the conductor is considered outside the building but doesn't address raceways that are not concrete and 230.7 which tells me nothing else can be in that raceway but the SE and bonds/grounds. I skimmed all of 230 but didn't find anything obvious so I'm asking you guys first before deciding which route to go. No need to worry though since permits WILL be pulled. I made that obvious to all three.

Thanks for the help.
As I was reading your question and assuming this was a 200 amp service, my first thoughts were that you cannot go out the back of the meter socket because you don't have sufficient room for the proper bending radius of the conductor as allowed by code, although it has been frequently done that way for many years. The only other reason I can think of is the length of the SE cable from where it enters the building to where it enters the service panel may exceed what is allowed by code. The best thing to do is to perhaps trust your electrician since he has to satisfy the inspector. Personally, I don't like SE cable. I'd rather see conduit leaving the bottom of the socket down to the band board where I would like to see an LB to enter the house through the band board and then a 90 degree elbow over the top of the foundation and into the top of the panel. You can do this with either PVC Sch 40 or EMT. If you use EMT, however, you'll need a bonding bushing at both the meter socket and the panel.
 
  #3  
Old 02-03-10, 03:11 AM
W
Member
Join Date: Jun 2008
Location: VA.
Posts: 813
Received 1 Vote on 1 Post
As stated, most areas only allow 5-6' of unfused service cable inside the house. This rule varies by area.

If you install a disconnect outside, then it doesn't matter how much comes inside after that.

It's possible that this is what the "other 2" are going to do in order to keep the panel in the same spot.
 
  #4  
Old 02-03-10, 04:45 AM
pcboss's Avatar
Forum Topic Moderator
Join Date: Jul 2002
Location: Maryland
Posts: 15,144
Received 85 Votes on 73 Posts
My thought is that the one is more concerned about the length of unfused cable inside. I have no problem with SE cable. It is very common and the only time I see it need to be replaced is after many years of UV exposure has cracked the jacket. UV also affects the insulation of individual conductors.

At least here the power company determines where the socket can be located. One power company does not allow any penetrations out of the back or top of the socket.
 
  #5  
Old 02-03-10, 08:46 AM
I
Forum Topic Moderator
Join Date: Feb 2005
Location: Near Lansing, Michigan
Posts: 10,944
Received 43 Votes on 41 Posts
I agree with your first electrician, that the unfused cable should remain outside the house. The code requires that the length of unfused conductors inside the building be "as short as practical". In this case it sounds like it is practical to keep the conductor outside. To run the SE cable out the back of the box and through the house you would need a meter/main disconnect instead of a simple meter pan in my opinion.

I don't understand why you just can't come out of the bottom of the meter with a couple feet of conduit and LB through the block into the basement?
 
  #6  
Old 02-03-10, 09:50 AM
Niadh's Avatar
Member
Thread Starter
Join Date: Aug 2006
Location: USA
Posts: 223
Received 0 Votes on 0 Posts
Some more info to answer the questions. It is a 200 amp SE. The unfused run would be 3 feet max inside the wall and maybe another 2' in the basement to the box. It can come out of the bottom of the socket and immediately LB into the wall but the conduit can't run all the way to the basement because of an obstruction on the outside wall below the meter socket.

I see people are favoring the odd man out. If it was just a hundred are two more I'd not quibble but understand his estimate was over three times higher than the second highest and all three of the electricians are licensed so it seems to me to be more of a preference than an actual code issue.

Thanks for the help so far. I have some points to bring up when I call them back.
 
  #7  
Old 02-03-10, 09:59 AM
I
Forum Topic Moderator
Join Date: Feb 2005
Location: Near Lansing, Michigan
Posts: 10,944
Received 43 Votes on 41 Posts
Originally Posted by Niadh View Post
The unfused run would be 3 feet max inside the wall and maybe another 2' in the basement to the box.
That actually isn't too bad. Most inspectors want to see the unfused cable less than 5', so you might be okay.

It can come out of the bottom of the socket and immediately LB into the wall but the conduit can't run all the way to the basement because of an obstruction on the outside wall below the meter socket.
What kind of obstruction? A little work with a heat gun and you can make a kick bend in PVC conduit to almost any shape.

If it was just a hundred are two more I'd not quibble but understand his estimate was over three times higher
That does seem unreasonable for what seems to be a minor difference in installation.
 
  #8  
Old 02-03-10, 01:12 PM
Niadh's Avatar
Member
Thread Starter
Join Date: Aug 2006
Location: USA
Posts: 223
Received 0 Votes on 0 Posts
The obstruction is a structure the size of a large doghouse that houses a backup generator. It is stick built on a cement pad and non-movable.

I went down to the poco's office and talked to the guy that handles the permits. He didn't see a problem with running threw the wall as long as the unfused run was less than 12 feet! He did say he'd like to see it come out the bottom of the socket and LB into the wall instead of out the back of the socket which I have no problem with.

I do still have a question left. Why is it SE has such a large bend radius (25" diameter if my math is right) but if you put the same wire in triplex form in conduit you can bend it almost at 90 degrees in an LB? Shouldn't 4/0 have to have a bend diameter in the 6" range? That would never fit in a 2" LB or probably a 3" LB. Are the rules different in conduit?
 
  #9  
Old 02-03-10, 08:40 PM
CasualJoe's Avatar
Member
Join Date: Jan 2010
Location: United States
Posts: 10,645
Received 85 Votes on 75 Posts
Originally Posted by Niadh View Post
The obstruction is a structure the size of a large doghouse that houses a backup generator. It is stick built on a cement pad and non-movable.

I went down to the poco's office and talked to the guy that handles the permits. He didn't see a problem with running threw the wall as long as the unfused run was less than 12 feet! He did say he'd like to see it come out the bottom of the socket and LB into the wall instead of out the back of the socket which I have no problem with.

I do still have a question left. Why is it SE has such a large bend radius (25" diameter if my math is right) but if you put the same wire in triplex form in conduit you can bend it almost at 90 degrees in an LB? Shouldn't 4/0 have to have a bend diameter in the 6" range? That would never fit in a 2" LB or probably a 3" LB. Are the rules different in conduit?
First of all, you don't run SE cable in conduit or through an LB condulet. When you run SE cable through the wall you could use a sill plate or just run it through a hole cut with a hole saw and seal the opening with duct seal. The sill plate makes a much neater installation. I can't speak to the bend radius of 4/0 Alum SE cable because I don't have a code book with me at home and haven't used it in many years (I hate the stuff). If you are running individual conductors in conduit, you would most likely be running type XHHW Alum conductors, THHN/THWN is hard to find in Alum in my area. The 25" bend radius you are speaking of most likely pertains to the SE cable assembly and not individual conductors. If you would use conduit, you could use 2/0 copper THHN, it's an easy install.
 
  #10  
Old 02-03-10, 08:44 PM
CasualJoe's Avatar
Member
Join Date: Jan 2010
Location: United States
Posts: 10,645
Received 85 Votes on 75 Posts
"He didn't see a problem with running threw the wall as long as the unfused run was less than 12 feet!"

12 feet seems a little long, I think code is something like 7 feet. But, I haven't had to be concerned with that rule for a long time so I haven't looked it up recently. What ever the AHJ says is what you should go by.
 
  #11  
Old 02-03-10, 09:37 PM
pcboss's Avatar
Forum Topic Moderator
Join Date: Jul 2002
Location: Maryland
Posts: 15,144
Received 85 Votes on 73 Posts
The NEC only states the unfused cable be "as short as practical". It does not specify a definitive length. I would not think that 12' is "as short as practical" but that is me.
 
  #12  
Old 02-07-10, 06:01 PM
CasualJoe's Avatar
Member
Join Date: Jan 2010
Location: United States
Posts: 10,645
Received 85 Votes on 75 Posts
For reference, if you check Table 312.6(B), NEC, you'll see that the typical 200 amp residential meter socket does not have sufficient space for the proper bending radius when using the back knockout. This is one of those times I don't agree with the NEC.
 
  #13  
Old 02-08-10, 03:16 PM
P
Member
Join Date: Feb 2002
Location: port chester n y
Posts: 2,117
Received 0 Votes on 0 Posts
Discuss with the electrician the possibility of routing Flexible Metal Conduit (FMC) in the wall, the FMC connecting to the Service Panel at one end, and at the other end , the FMC would connect, using a 90 - degree connector ( for the needed 90-degree bend inside the wall ) to a steel conduit coupling thread into a steel nipple which in turn is threaded into the "back" of an LB which is X ft below the bottom of the Meter-Socket.

Obviously , the breeching in the wall for the LB would be as low as possible to minimize the lenth of the FMC.


The conduit "Fill" for the FMC would be three #00 copper conductors which determines the trade-size of the FMC.

Good Luck !!!
 
Reply
Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description:
Your question will be posted in: