Reuse Service Panel???

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  #1  
Old 12-07-06, 02:40 PM
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Reuse Service Panel???

I've currently got two meters on my property. One of which is used for the well, and a 20A service to my shed. The other was used for a 50A service to the mobile home that use to reside here.

The service panel that was used for the 50A service to the old mobile home is rated for 125A max (from label). I am building a cabin that will need some power to it, and was thinking, hoping that I could run a conduit from the pole/service panel to the cabin where I would put a subpanel in.

My thought was that I would want 100A service to the cabin, but that is just a guess, so here are the details, and hopefully you can tell me if I'm off base on this or not.

The water heater and range will be gas. The heat is passive solar with wood stove. If I need more heat then that I will install a gas wall heater, no electric heat needed. If I need to have cooling, which I highly doubt, I will use an evaporative cooler which runs on a 20A 110 circuit.

The rest of the appliances (refridge, washer, dryer) will be electric, as well as lights, ceiling fans (2) and all of the other creature comforts. The cabin is about 800 sq. ft. and I anticipate 7 20A circuits, which for the most part will be lightly used.

The location for the subpanel is about 90' from the pole that has the current service panel/meter, so with the vertical, the run should be between 100-110' long.

BTW, I'm open to switching the dryer out for a gas dryer if that reduction in the electrical load would save me alot.

Ok, so my questions are:

1. Am I correct that the panel in the cabin will be a subpanel? I assume then that I will want a four wire feed to it.

2. Does it seem reasonable for me to use 100A service to this cabin? The MH being replaced only had 50A service, but it was about 40' closer to the pole.

3. What would be the appropriate wire sizes for this size usage?

4. Should I be putting in a ground at the cabin, or do I not need that since I'll be running four wires?

Thanks in advance!
 
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  #2  
Old 12-09-06, 02:21 PM
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1)This panel would only be a sub, if the main disconnect is located at the meter location.Otherwise it is a main.

2)The cabin is a dwelling and needs to meet the code, so with out too much detail, A 100A service is the minium you can have.

3) #2 AL. is good. Now we need the wireing method, IE: direct bury,conduit, over head, etc.

4) the ground would be located at the meter socket (i f main disco). Or at the cabin. The metal water pipe in the cabin must be bonded to the ground.

More detail on this when other items are settled.

Almost forgot, Used panel, How old is it. Panels are inexpensive,but if it's newer and in good shape, you could. If you don't have all the breakers you need now,
I would go with a new panel. (thats the route i would go anyway.)
 
  #3  
Old 12-09-06, 04:43 PM
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Originally Posted by lectriclee View Post
1)This panel would only be a sub, if the main disconnect is located at the meter location.Otherwise it is a main.

2)The cabin is a dwelling and needs to meet the code, so with out too much detail, A 100A service is the minium you can have.

3) #2 AL. is good. Now we need the wireing method, IE: direct bury,conduit, over head, etc.

4) the ground would be located at the meter socket (i f main disco). Or at the cabin. The metal water pipe in the cabin must be bonded to the ground.

More detail on this when other items are settled.

Almost forgot, Used panel, How old is it. Panels are inexpensive,but if it's newer and in good shape, you could. If you don't have all the breakers you need now,
I would go with a new panel. (thats the route i would go anyway.)

So the reused service panel at the meter will only have a 100A 220 circuit in it, which will be buried in conduit run the 100-100' to the subpanel in the cabin. The panel in the cabin will be a new panel with the 20A 110 circuits in it. The reason I don't want to put in a new panel is then I have to pull the meter or deal with live wires, neither of which I want to do, and I don't see anything wrong with this panel since it's rated for 125A and I'm only using 100A. The box itself looks like it's in good shape, I'm guessing it's about 8-10 years old and was installed by the previous owner when he setup the mobile home that use to be here. Is there some quanatative reason why I would upgrade this panel, other then if I wanted to run more then 125A to the cabin?

-- bz
 
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Old 12-09-06, 05:09 PM
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Ok, so at the meter location is a main disconnect. Rated at 125A, then conduit with 4 wires from it to a sub panel in the cabin. That sounds fine.
At the meter this breaker will be changed from a 50A to a 100A.this panel can be main lug only or breakr.I would go with the breaker,only because of the distance from the meter.
In the cabin the neutral and ground bus will be isolated. and from the ground bus a bonding cable will be installed on the metal water pipe.

If this is the case, then yes, you can do that.

You will still be dealing with live parts at the meter disconnect. You will need to resize or check the ground to make sure it is rated for 100A.
 
  #5  
Old 12-09-06, 05:24 PM
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Only one difference from what you said, there is no metal water pipe, so I will be putting in a grounding rod. Good point that I need to verify the ground size at the main service panel.

-- bz
 
  #6  
Old 12-11-06, 06:55 PM
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You need a building disconnecting means!

You must have a building disconnecting means at the cabin. A main breaker panel installed nearest the point of entry of the feeder conductors would satisfy this requirement. You will also have to have a grounding electrode system at the cabin. If the cabin will have a concrete foundation you should install a concrete encased electrode in the footer. If the footer contains reinforcing steel you must use it as part of the grounding electrode system. That would be a much better electrode than driven rods and it is easier to install. Once you have a concrete encased electrode no driven rods are required. Does you well have a metal casing? Do you need to run a new water line to the cabin?
 
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Old 12-11-06, 09:28 PM
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I like easier!

I'm putting in the rebar tomorrow (pour scheduled for Monday, yea!), so I'll try to get a leave a piece of rebar hanging out to tie into near where the service panel will be installed. The well is located over 100' away, and the new water line is PVC.

-- bz
 
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Old 12-12-06, 09:14 PM
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Is the new water line trenched yet?

When you trench for the new water line you will have the opportunity to run a bare number two copper wire in the trench to bond the metal well casing into the Grounding Electrode System. A deep drilled metal cased well is probably the best electrode a rural property can have. The low impedance electrode can save you from a lot of surge and spike damage. Of course it may well be the Grounding Electrode Conductor buried with the water line behaving as a ground ring without meeting the code definition that is doing the heavy lifting. The grounding electrode conductor only needs to run to an electrode using a trench you are going to dig anyway. A ground ring must circle the entire structure. So unless it is installed around the footer before the foundation is back filled you have to dig a trench just for it.
 
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Old 12-12-06, 09:33 PM
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Good call Tom!
 
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