What wire is required for 100 amp [Service]

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Old 05-31-16, 06:11 PM
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What wire is required for 100 amp [Service]

Hi,

Is 1/0 copper THHN wire acceptable for going from the district supply to the meter base for an overhead supply for 100 amp service? I have heard it needs to be 'UV' rated since it is outside, the 1/0 copper THHN I bought just says 'weather resistant'. They had aluminum that was 'UV rated' but I don't want to get aluminum because I would have to upgrade my conduit to fit the larger aluminum wire while keeping the same capacity of my current copper wire that I am replacing...Just want to make sure I am up to code before I put the wire in and have it inspected.

I am in Whatcom County, Washington State if that makes a difference (I'm obviously not a professional electrician and am not sure if codes change in different areas...)
 

Last edited by ray2047; 05-31-16 at 08:14 PM. Reason: Clarify title.
  #2  
Old 05-31-16, 06:41 PM
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That's not your responsibility. The electric company does that and they follow their own rules not NEC. You should not be running any wire from pole to house or am I misunderstanding you.
 
  #3  
Old 05-31-16, 07:02 PM
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You are only responsible from the meter base to the weather head. Overhead wiring is done by the power company.
 
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Old 05-31-16, 07:37 PM
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Whatcom County has FOUR different electrical utilities and it DOES matter as to which one serves your area. They are, City of Sumas, City of Blaine, Puget Sound Energy or Whacom County Public Utility District.

Further, ALL codes are LOCAL. Depending on where in Whatcom County you live you may be covered under a city code, a county code or the state electrical code.

Each utility will have specific rules for service.
 
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Old 05-31-16, 08:04 PM
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I am talking about the meter base to the weather head (plus 18" past to my knowledge). Inside Bellingham city limits
 
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Old 05-31-16, 08:12 PM
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This is what I am repairing
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Old 05-31-16, 08:19 PM
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I am talking about the meter base to the weather head (plus 18" past to my knowledge).
Then you are not asking about:
overhead supply to meter base
so I have clarified your title.

#3 or #2 THWN copper would be fine. UV rating isn't really a consideration.
 
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Old 05-31-16, 08:27 PM
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Awesome, thanks for the clarification. I have already bought 1/0 copper THHN. Can i use this? Or do I need THWN?
 
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Old 05-31-16, 09:31 PM
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This is what I am repairing
You are replacing the meter pan, service conduit and weatherhead... correct ?

1/0 is a little large but ok. You'd need to make sure it fits into the lugs on the 100A meter pan.
 
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Old 05-31-16, 09:34 PM
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Check the writing on that wire. What some BigBox stores call THHN is actually THHN/THWN. If it only says THHN no, you can't use it. 1/0 is going to be harder to use and you need to make sure it fits the lugs. If it was someone at a BigBox store that advised you to buy it you might try to see if they will take it back and give you #2.
 
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Old 05-31-16, 10:10 PM
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Forgive me for not knowing all the correct terminology, but I am replacing the wire that goes from the meter base to the weatherhead. I am hoping to not have to change the conduit. I got 1/0 because that is what my friend recommended that is a certified electrician, although he usually does not do this type of job so maybe his advice was incorrect. I believe he told me 1/0 copper because I do have lots of machinery that at peak times could be close to maxing out my power, and because if I went for aluminum that would give me the same amp capacity I would most certainly have to get a larger conduit.
 
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Old 05-31-16, 10:14 PM
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You will have a hard time pulling 1/0 cable in what looks like an 1-1/4" pipe.
You will have a much harder time getting 1/0 wire into the lugs of that old/tired meter pan.
That upper right meter receptacle looks cooked.

He most likely mistakenly said 1/0 copper. He probably meant 1/0 aluminum.
 
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Old 05-31-16, 10:18 PM
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Thanks, Ray. Printed on the wire is THHN/THWN-2, so sounds like I should be ok...? I think the reason my electrician friend said to get 1/0 is because he said that looks like what the existing wire is from the picture, so hopefully I will be ok fitting it into the lugs.
 
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Old 05-31-16, 10:22 PM
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Three 1/0 conductors (wires) won't fit what you have. You would need at least a 1 1/4" conduit. 4 gauge copper or 2 gauge aluminum is normally OK for 100 amp service if it is a residence.

I would suspect that the inspection process would not allow you to keep that old meter base. You need to find out the rules before spending any more money. Check what permits are needed with your local town office. Also check the power company as they have their own rules - sometimes on their web site.
 
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Old 05-31-16, 10:22 PM
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Does anyone think the inspector will want me to change the entire [meter base housing]? Not sure if that is what you would call it, but notice the lining inside the meter base that has been burned...Name:  IMAG0218.jpg
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Old 05-31-16, 10:29 PM
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Thanks Astuff. I do currently have 1 1/2" conduit. I WAS worried about the meter base. I have already got the homeowner's permit, but they would not give me any information on requirements other than they just gave me this info for what code to follow:

2014 National Electric Code (NFPA 70) and Amendments - Chapter 51-54 WAC

The power company said as long as they see the stamp for the inspector they will hook it back up, no information beyond that.
 
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Old 06-01-16, 06:43 AM
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I would think the power company is going to want the socket replaced. I would not keep it if it had damage.
 
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Old 06-01-16, 08:14 AM
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I agree the socket should be replaced. The upper right meter jaw clearly has heat damage which will affect the connection integrity if the meter was reinstalled. A new socket will have the proper bending radius. Furd may have a better knowledge of the policy in your area, but in my area the power company provides basic residential meter sockets for free through local electrical suppliers.
 
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Old 06-01-16, 08:31 AM
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Furd may have a better knowledge of the policy in your area, ...
He hasn't told us who his serving utility is yet. Since he lives in Bellingham I think it is is safe to eliminate both City of Blaine and City of Sumas. That still leaves Whatcom County PUD and Puget Sound Energy. I don't KNOW but I suspect his utility will be PSE. If I am correct then here are the PSE service requirements. https://pse.com/accountsandservices/...uirements.aspx (I haven't read any of this.)

Retrofits are always suspect and one thing that jumps out to me is the weatherhead being under the eave overhang. I don't know about PSE but some utilities do not allow this anymore and require the mast to extend above the roof a specified distance, usually with a solid backstay resisting the pull of the overhead drop.
 
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Old 06-01-16, 09:39 AM
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Thanks, Furd. My service is Puget Sound Energy. I thought that was the only supplier in the area.
 
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Old 06-01-16, 10:06 AM
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I've never lived in Bellingham and the last time I was even near the city was probably twenty years ago. What I did know was that Whatcom County had a PUD so by going to their page I found out that there were three other electric utilities in the county.

The reference to Chapter 51-54 WAC (WAC= Washington Administrative Code) is merely the enabling legislation that adopts the 2014 National Electrical Code (and others) into law. I do not know if Bellingham has a city electrical code, defers to the county or if Whatcom County merely defers to the state code.
 
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Old 06-01-16, 10:37 PM
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The inspector called me back this morning. The 1/0 THWN I have is not necessary, a little big, but still acceptable. Did the repair today, crossing my fingers on the inspection tomorrow morning.
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Thanks everyone for your input
 
  #23  
Old 06-01-16, 10:46 PM
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Looking good. You know now to double check information from your friend. Have you verified it will fit your main panel lugs?
 
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Old 06-01-16, 10:52 PM
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I'm impressed.... you even put a bushing on the bottom connector.

Ray... it looks like the load side of the meter is in smaller cable.
 
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Old 06-02-16, 12:08 AM
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Yeah, it is smaller cable going into the panel (is that what load is?) Learn something new every day!!! I hope that won't be an issue for the inspector...
 
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Old 06-02-16, 12:19 AM
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load side of the meter is in smaller cable
Missed that. .
 
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Old 06-02-16, 04:39 AM
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Is a bonding bushing required on the bottom as it is a concentric knock-out?
 
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Old 06-02-16, 10:22 AM
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Looks like cable at the bottom, not metallic conduit.
 
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Old 06-02-16, 10:33 AM
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Yes, Ray. I only replaced the conductors from the weatherhead to the meter base. The conductors from the meter base to the main panel were not changed. They are #2, though, and what I put in is #1. Assuming that won't be an issue for the inspector...?
 
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Old 06-02-16, 11:10 AM
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The wiring size won't be an issue for the inspector.
 
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Old 06-02-16, 02:44 PM
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Inspection Approved!!:HF2:
 
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Old 06-02-16, 03:29 PM
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Excellent! Is this an old house you bought to fix up?
 
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Old 06-03-16, 07:55 PM
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Yeah, built in 1914. Lot's of 'character'.
 
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Old 06-03-16, 08:39 PM
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Bet besides character it has lots of knob and tube with strange connections no longer allowed.
 
 

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