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Old 04-02-2008, 01:07 PM   #1
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What size SE conductors


I'm building a detached garage this summer with a 100 amp service. I have an overhead service to the house and the house has a 200 amp service. I wold like to upgrade the meter base (what size do I need?) and come out of the bottom of the meter base with 2 sets of conductors, 2/0 copper for the house, and #4 copper for the garage
The question I have is: How do I size the service conductors inside the service mast, from the utilities overhead splice to the top of the meter base? Do these conductors need to be 250 MCM or can they be derated somehow?

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Old 04-02-2008, 01:36 PM   #2
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What size SE conductors


You have a 200 amp service, and that is all you have. What are you upgrading the meter base too? Your next size will be 320 amp/400 amp service. If you are putting a meter/panel combo and added a 100 amp breaker for the garage, then the service will stay the same.

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Old 04-02-2008, 01:48 PM   #3
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What size SE conductors


My 200 amp panel is in my basement. It's only a meter base on the outside of my house. I thought I would have to put a bigger meter base in if I'm going to feed the garage off the same mater base, but I don't know. What size meter base would I need? And what size SE conductors from the drip loop to the top of the meter?
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Old 04-02-2008, 01:51 PM   #4
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What size SE conductors


I'm assuming that you have the need for a bigger service and that the proper load calculation has been done to confirm a bigger service is needed?

When you use the term 'detached garage' that in my world equates to a 60 amp or less feeder to supply the electrical.

If you do need 100 amps at the garage and the present service will support that then you may use the unlimited tap rule at the meter either by installing double lugs or other listed tapping means. At the garage the tap feeder conductors must land on an overcurrent device rated not greater than the ampacity of the tap conductors. This of course all subject to the local codes departments approval.
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Old 04-02-2008, 01:55 PM   #5
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What size SE conductors


Are you wanting overhead service to the garage or underground?


You can feed the garage from a breaker installed in the main panel if you want. It would be a lot less of a hassle.
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Old 04-02-2008, 01:59 PM   #6
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What size SE conductors


Is it really a feeder if I come right off the meter base, I thought it would be another service per Article 230.40 exception #3
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Old 04-02-2008, 02:03 PM   #7
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What size SE conductors


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Originally Posted by Stubbie View Post
Are you wanting overhead service to the garage or underground?


You can feed the garage from a breaker installed in the main panel if you want. It would be a lot less of a hassle.

I want to go underground to the garage

I don't have a core drill and I have a poured concrete basement, it would be easier for me to come off the bottom of a meter base attached outside my house. I also want to keep the 200 amp just for my house.

I will put a 100 amp panel in the garage for compressors and such.

So my question is, do I add up the 2 services 200 + 100 = 300 amps to calculate the SE conductor size from my drip loop to the top of my meter base, or is there some kind of derating I can use?
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Old 04-02-2008, 02:30 PM   #8
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What size SE conductors


Yes 230.40 would cover your application. The conductors to the garage are service entrance conductors tapped on the load side of the meter can.

I was incorrect in refering to the feeder tap rules. My mistake. Better slow down and read a bit better.

You must have double lugs if your going to connect inside the meter can. The meter can may or may not accept them you will have to see if a double lug kit is made for it. Otherwise you need to go to a 320 meter bse with double lugs or splice outside the can. You are not allowed to splice in the meter can. You could splice outside of it in a trough.
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Old 04-02-2008, 02:35 PM   #9
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Thanks Stubbie,
I will go with a 320 amp meter base. I found something called "load tap connectors" which are double lugs for the meter base, so I will be using them.

Now, how about the size of my SE conductors from the drip loop to the top of the meter, do they really have to be 250 MCM? And thats only if I am allowed to use Table 310.15(b)(6), which I don't know if I can since the garage isn't a dwelling.
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Old 04-02-2008, 02:57 PM   #10
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What size SE conductors


You may use 310.15 (b)(6) imo though a quick check with local codes may be in order as there is a lot of controversy when to use this table in your application. If your going to put in a 100 amp main breaker panel then the service conductors to the detached garage only need to be #4 awg thwn copper or #2 awg aluminum. 3 wires H-H-N to the garage. Or if table 310.15 b 6 is not allowed to your detached garage then #3 copper thwn or #2 al.

The 250 MCM would be the aluminum coming in from the overhead. For a 200 amp dwelling only 4/0 aluminum is required unless you upsized to 250 mcm for some reason.

Is this what you connected to the utility with at the drip loop.... 250MCM?

There are many types of meter cans that can be used for your purpose. If your wanting to look at options....there are many ways to go with this. Might look over at the milbank meter website to get an idea.

A 320 meter base will come with double lugs.

Last edited by Stubbie; 04-02-2008 at 03:42 PM.
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Old 04-02-2008, 03:37 PM   #11
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What size SE conductors


Some meter bases will take these load side taps and you could keep your 200 amp meter base. I would go this route if possible. Do not exceed 200 amps on the service entrance.


http://www.milbankmfg.com/Products/C...M5%2008-04.pdf

Last edited by Stubbie; 04-02-2008 at 04:40 PM.
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Old 04-02-2008, 04:24 PM   #12
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What size SE conductors


I doubt you could do both a 200 amp feed to the house and a 100 amp feed to the detached garage. This would allow for the the 200 amp service entrance to be overloaded. You would have to do 100 amps to the house and 100 amps to the garage. The lugs allow for you to keep the same meter base as long as you do not exceed 200 amps possible on the service entrance conductors. If you install a 320 meter base you would be able to do both a 100 amp feed and 200 amp feed but you would have to get a upgrade in service.

Last edited by Stubbie; 04-02-2008 at 04:38 PM.
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Old 04-02-2008, 04:50 PM   #13
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What size SE conductors


Quote:
I will go with a 320 amp meter base. I found something called "load tap connectors" which are double lugs for the meter base, so I will be using them.
Quote:
So my question is, do I add up the 2 services 200 + 100 = 300 amps to calculate the SE conductor size from my drip loop to the top of my meter base, or is there some kind of derating I can use?
I reread this and I should clarify that you can do this but the service and the service entrance conductors must be sized for the load. I believe that is what your asking. In this case your new meter will be rated 400 amps... 320 amps continuous but your service entrance conductors must also be rated for the load also.

To do a 100 amp feed to the garage and a 200 amp feed to the house from the meter will require a 400 amp service.

Otherwise you need to feed the garage from a 100 amp breaker in the 200 amp main panel.

Last edited by Stubbie; 04-02-2008 at 04:52 PM.
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Old 04-02-2008, 05:35 PM   #14
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What size SE conductors


You guys kill me sometimes, this is way above DIY work, yet the answers flow....
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Old 04-02-2008, 07:02 PM   #15
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What size SE conductors


Chris

Assuming he has the poco connect the driploop and pull his meter I see nothing that difficult about this. This type work is done quite often by homeowners that have the skill level to accomplish it, when they are building a new home and acting as the contractor.

Or are you saying incorrect information has been given? If so please correct me for any errors.

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