Upgrading to 200 amp meter/main and 125 sub.

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  #1  
Old 07-22-13, 11:43 PM
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Upgrading to 200 amp meter/main and 125 sub.

I have an electrician coming to do the final connections but I want to install the 200 amp meter main and the 125 sub, but I have some questions. Right now I have a 100 amp meter main, which is too small, on the house which needs to be moved, as it is no longer within proper code. I decided to move the new 200 amp meter/main to the side of our detached garage. We have an apartment above the garage so I think that 75 amps will be enough to dedicate to the building. I trenched from the 200 amp main to the house where I will put a 125 amp sub panel. My first question is this -

Are the three #2 wires that will run from the 200 amp main to the 125 sub, running from a 125 amp breaker housed in the 200 amp main?

If I am 24 inches deep for the underground in a 1 1/2 inch schedule 40 pvc, can I lay another 1 1/2 inch line next to it for cable, phone etc?

Are bonding bushing just for metal conduit? You don't use them for pvc entry into the panel right?

Thx for any knowledge.

Jeff
 
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Old 07-23-13, 02:46 AM
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Welcome to the forums.

Yes the three #2 and one #8 will be connected to a 125 amp breaker in the 200 amp panel. The #8 is for the separate ground bar in the 125 amp sub panel.

You can lay two pipes side by side in the trench.

Bonding bushings are not used on PVC pipe.
 
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Old 07-23-13, 03:18 AM
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Are the three #2 wires that will run from the 200 amp main to the 125 sub, running from a 125 amp breaker housed in the 200 amp main?
You mean two wires from the breaker and two from the neutral/ground bus. And, maybe, if the stab rating is large enough. You will find the stab rating on the meter/main's label. The stab rating is the largest breaker you are allowed to use. For panels with two columns of breakers, the left and right spaces share a stab. Max out the rating on one side and the breaker spaces that share those stabs must be left blank.

If the stab rating is too small, you would have to use the tap rules.

If I am 24 inches deep for the underground in a 1 1/2 inch schedule 40 pvc, can I lay another 1 1/2 inch line next to it for cable, phone etc?
It's legal, but a bad design. To avoid induced interference from the power lines, fill the trench until it's 6 inches deep. Then lay the low voltage pipe.
Are bonding bushing just for metal conduit? You don't use them for pvc entry into the panel right?
For PVC you don't use bonding bushings. But, larger than a certain size (1"?) you do use regular bushings.
 
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Old 07-23-13, 04:19 AM
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Don't forget you'll need a grounding electrode system at the garage AND the house.
 
  #5  
Old 07-23-13, 07:09 AM
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Ground rods

Yes I have 3 ground rods; 2 for the main (6 feet apart and connecting to the water line) on garage and one for the sub panel.

I will fill in the trench before I lay the low voltage line thx

Also, I googled "stab rating" and nothing came up, so I am confused about what this is. I think that what you are saying though is that if I am putting a 125 amp breaker on one side, I will not be able to use the other. This is ok since the main is 30/40 and will not have much allotted for the garage/apartment.

The 125 subpanel is called a "main lug" and has 20/20 which I hope is sufficient (2 ranges and AC condenser are the big draws)

Thx,

Jeff
 
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Old 07-23-13, 07:16 AM
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Both building will need a means of disconnect. It does not sound like you have one where the main lug panel is installed.

Did you consult the power company to see if the location of the service was acceptable?

I hope you were asking about copper conductors ampacities.

Without knowing the conductor material the conduit cannot be sized. Aluminum conductors would be larger for the same ampacity.
 
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Old 07-23-13, 08:44 AM
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pcboss reply

Thx pcboss

The main has the 200 amp and the 125 lug both have the standard main switch in the box, if that is what you are referring to.

Yes copper for sure

Power company came and did a spot check yes
 
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Old 07-23-13, 11:38 AM
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The main has the 200 amp and the 125 lug both have the standard main switch in the box, if that is what you are referring to.
If the 125 amp panel has a main breaker in it, it isn't a main lug panel, but a 125 amp main breaker panel. It is permissible, however, to add a 125 amp breaker to the bus of a main lug panel with a retaining clip to make your own main breaker.
 
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Old 07-23-13, 01:16 PM
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Two ground rods at each location.

Also, I googled "stab rating" and nothing came up, so I am confused about what this is.
It is permissible, however, to add a 125 amp breaker to the bus of a main lug panel with a retaining clip to make your own main breaker.
Two metal power buses run inside the panel. The power buses have formed extensions that the breakers clip onto to make the electrical connection. The stab rating is how much power (amps) each extension can handle. The stab rating is listed on the label inside the front cover of every panel. Do not exceed the stab rating. Not with one breaker or with two breakers on the same stab. And not when you make a main breaker by using a retaining clip.
 
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