Feeder Wire size

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  #1  
Old 01-07-12, 01:08 AM
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Feeder Wire size

Hi everyone! I hope someone can give me a quick reply if I am safe to use 4/3 AWG + G copper for a Feeder Line from the 100A meter box to the Sub-Panel inside the house. The length is about 50 ft from the meter box up to the subpanel. The sub-panel is also provided with a 100A main disconnect. Thank you in advance.

tinoM
 
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  #2  
Old 01-07-12, 01:45 AM
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Which type of " Line " are you refering to the SER cable or THHN/THWN or others ??

The reason why I asked due there are some amp rating that will affect depending on which type of " line " you are using.

Merci,
Marc
 
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Old 01-07-12, 07:10 AM
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if I am safe to use 4/3 AWG + G copper for a Feeder Line from the 100A meter box to the Sub-Panel inside the house.
And......is there a 100 amp breaker or fusible disconnect at the meter? You didn't say, but there must be if the panel in the house is a subpanel. The terminology you use makes this sound as if you are using NM-B cable, but it could also be SER cable or individual conductors in conduit, like Marc asked, which is it?
 
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Old 01-07-12, 07:19 AM
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IS this a sub panel that is fed off the main panel or are you planing on feeding it off the meter. While you can have up to six main disconnects in a building, they must be grouped together. If the "sub panel" is going to be a real sub panel in a remote location, it will need to be fed off the main service.
 
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Old 01-07-12, 01:47 PM
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You also might only be able to install a 90 amp breaker. Clarification on thw wiring type is still needed.
 
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Old 01-08-12, 03:47 PM
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Sorry for my incomplete info. The wire in question is the feeder wire from a new meter box with a 100A circuit breaker only and the Sub-panel is located inside the house protected also with a 100A ciricuit bereaker. I am planning to use a NM-B 4/3 AWG+G from the meter box to the sub-panel. (The wire from the weather head to the meter will be four single wire THHN 4 AWG +G). The new meter box is a lateral to the existing service drop. Hope this information is enough for clarity.
Thanks again,
tinoM
 
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Old 01-08-12, 04:06 PM
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Quote"The wire in question is the feeder wire from a new meter box with a 100A circuit breaker only and the Sub-panel is located inside the house protected also with a 100A ciricuit bereaker. I am planning to use a NM-B 4/3 AWG+G from the meter box to the sub-panel. (The wire from the weather head to the meter will be four single wire THHN 4 AWG +G). "
#4NM is rated for only 70 amps. You can not protect it with a 100 amp breaker. #4 THHN is rated 85 amps. What are you trying to do? your conductor sizes are too small.
 
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Old 01-08-12, 05:04 PM
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I can't quote the code paragraph because I don't have a recent edition of the NEC with me, but I don't think the paragraph I am thinking of has changed. It has almost forever stated that #4 copper conductors are allowable for a 100 amp single phase dwelling service or feeder. No, #4 copper isn't rated for 100 amps, but it is allowed by NEC. This would be in the same paragraph that allows 2/0 copper conductors to be used for a 200 amp single phase dwelling service or feeder. I believe it is in section 310. That being said, if it were my home, I'd use #3 copper conductors like a commercial service.
 
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Old 01-08-12, 05:48 PM
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Type NM cable cannot be used as a service entrance cable. You would need to use something like SE-U cable.
 
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Old 01-09-12, 12:34 PM
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Thanks for your quick replies.
pcboss you mean I cannot use NM cables from the meter box to the sub-panel? If so, I have to use SE type? Please clarify. Casual Joe, I did find a copy of the NEC 2011, on Art. 315.15(B)(7) and listed on Table 310.15(B)(7), 4 AWG is rated for 100A Service or Feeder rating. I can go to the next wire size if needed. Before I proceed in buying the right materials, I will check also with the power company their other requirements. I would appreciate more inputs on this question. Thanks again.
tinoM
 
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Old 01-09-12, 12:58 PM
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Table 310.15(B) can only be used where the cable carries the entire load of the dwelling. Otherwise you need to use 310.16.

Type NM cable cannot be used as service cable. You should use SE between the meter and the panel.

How do you plan on providing overcurrent protection to the subpanel?
 
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Old 01-09-12, 07:36 PM
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You were going to use 4-3/G NM cable with 3 insulated conductors before so I am assuming the main service OCP device is at the meter. This also makes the panel in the house a subpanel. pcboss is correct, you can't use NM cable, but you can use SER cable. The only problem you might have is finding SER cable with copper conductors, most supply houses stock it in aluminum. But, I know you could order it. The other copper alternative would be 1 1/4" conduit with THHN/THWN conductors. OR.....you could use #2 aluminum SER cable.
 
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Old 01-09-12, 10:34 PM
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Thanks everyone. I found today that the Big orange store have in stock SER cable #2/3+G AWG Alum. I still have to check an electrical store here if they have SER in copper. The sub-panel is protected with a 100A circuit breaker. How about the wires from the service drop to the meter, can I use 4 single #4 AWG THHN (2 LINE+N+G) in 2" rigid conduit?
tinoM
 
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Old 01-10-12, 03:19 AM
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In the drop from the connection to the meter only needs to be 3 conductors, H H N.
 
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Old 01-10-12, 06:10 PM
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How about the wires from the service drop to the meter, can I use 4 single #4 AWG THHN (2 LINE+N+G) in 2" rigid conduit?
Like pcboss says, all you need is 3 conductors, they would have to be copper to use #4. You don't need 2" rigid conduit unless it extends through the roof as a mast to support the service drop. If the service drop is supported by something other than a conduit mast through the roof, you could use 1 1/4" conduit.
 
  #16  
Old 01-10-12, 10:45 PM
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Thanks again everyone. Sorry I missed that one, two hots +N. I will check again with the power company since they gave me a brochure and it says 2" Rigid conduit required on the service drop.
Since this new meter is to be installed lateral to the existing one, they may approve to use a smaller conduit size. I will come back to you guys for more inputs.
tinoM
 
  #17  
Old 02-22-12, 11:51 PM
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Hi everyone,
I posted this querry here as it related to this thread. I am pulling a SER AWG 2/3 AL from the crawl space going out to the meter box outside. From the wall where the cable comes out it will be installed in a 1-1/2" EMT conduit vertically up to the meter box about 5ft high. I am planning to use either an LB or a 90 deg EMT elbow where the cable comes out and connect it vertically up to the bottom of the meter box. My question is: 1) If I am going to use an LB, can I can strip the outer covering of the SER cable from the LB up to the circuit breaker inside the meter box? The reason for this is I can insert the wires inside the LB easily. I can forsee the difficulty of inserting and bending the cable inside the LB. If not allowed then I will use a 90 deg EMT. Any recommendation and or suggestion is highly appreciated. Thank you in advance,
tinoM
 
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Old 02-23-12, 05:32 PM
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From the wall where the cable comes out it will be installed in a 1-1/2" EMT conduit vertically up to the meter box about 5ft high. I am planning to use either an LB or a 90 deg EMT elbow where the cable comes out and connect it vertically up to the bottom of the meter box.
Why are you using the conduit, is it needed for additional protection of the cable? SER cable can be used outdoors.
 
  #19  
Old 02-24-12, 09:45 AM
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Thank you for your reply. The POCO requires it. They accept 1-1/4" PVC but since I have a spare 1-1/2" EMT I'm using it for this purpose. I haven't asked poco if stripping this cable on this portion is acceptable practice.
tinoM
 
  #20  
Old 02-24-12, 09:56 AM
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In general wires inside cable are not rated or marked to be used as individual conductors outside the cable.
 
  #21  
Old 02-27-12, 01:08 AM
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Thanks ray for your reply. I understand that it has been discussed in some of the threads here about stripping cables of its outside cover is not recommended. I was able to install/pull the cable using a 90 deg EMT elbow and looks perfect without much hassle of inserting/pulling the cable. Hopefully, the poco will be able to connect power to the meter this coming week. Thanks again for all your help.
tinoM
 
  #22  
Old 02-27-12, 07:30 AM
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Good luck with the PoCo. Let us know how it turns out.
 
  #23  
Old 02-27-12, 06:46 PM
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I was able to install/pull the cable using a 90 deg EMT elbow and looks perfect without much hassle of inserting/pulling the cable. Hopefully, the poco will be able to connect power to the meter this coming week.
I am hoping you know the metal conduit must be properly grounded. This would call for a bonding bushing inside the meter socket can.
 
  #24  
Old 03-01-12, 01:29 PM
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Thanks everyone. Finally the city inspector approved the installation and the POCO already connected power to it without problem. As an additional info, I did use XHHW wire from the weatherhead to the meter box. The store told me that this type are now commonly used by contractors here. Thanks again.
tinoM
 
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Old 03-01-12, 01:37 PM
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Thanks for the update and added info on wire type.
 
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