200 Amp Service Installation


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Old 11-05-13, 08:18 PM
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Question 200 Amp Service Installation

I am installing a new 200 amp service in my house. I have a 200 amp meter / breaker box and a 200 amp main panel. My first (main) panel is far enough away from the meter that I need to have a breaker at the meter (which is why I went with the combo unit). I would like to run the feeder wire between the meter and the main panel underground and in Schedule 80 conduit.

I have talked to different people and searched on the internet but don't have 100% clear answers to my questions which are below. Please let me know if you need anymore details and I will be glad to provide them.
  • I understand Aluminum feeder cable is cheaper; yet isn't copper a better conductor of electricity? Which is the best to use for the run between the meter and the main panel?
  • I am confused between THWN and USE. All I want to know is what wire do I need to buy that handles 200 amps and can be run in Schedule 80 conduit underground? I know it's 4/0 Aluminum or 3/0 Copper but what type? Where do I find it in Quadplex?
  • The electric company told me I need to run four wires from my meter to my main panel (Hot-Hot-Neutral-Ground). Does this mean the ground rod(s) are installed at the meter or the main panel? Are their two ground rods or just one? If there are two does #1 and #2 go directly to the meter(or panel) or does #1 go to #2 and #2 goes to the meter(or panel)? I get confused since the meter has a 200 amp breaker in it.
  • How deep do I need to bury the conduit?
  • In Indiana the Ground and Neutral bars are connected to each other in the panel. Does this happen in both the meter box and the main panel or just one of them in my situation?
 
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Old 11-06-13, 01:27 AM
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1. Yes, copper is a better conductor than aluminum. If you can afford the copper it is the best in my opinion although there is nothing wrong with properly installed aluminum.

2. THWN is a Thermoplastic, High temperature, Waterproof, Nylon jacketed single conductor. USE is a service entrance cable. Cable means more than one conductor with an overall sheath. Cable is generally not used in conduit although there are exceptions.

3. Although the term is freely used, there is no such thing as a "main" panel. The meter/circuit breaker panel is correctly called a "service" panel. The word "service" has a specialized meaning ion the electrical codes, it is the point where the electrical system changes from the utility's wiring to the premises wiring. An overhead service consists of the "service drop" (utility's wires from pole to the weatherhead), the service conductors (conductors from the weatherhead to the meter socket and continuing to the main circuit breaker inlet connections) and the meter itself. That first circuit breaker after the meter is called the service disconnect. All wiring after that point is either a branch circuit or a feeder.

The service also contains the Grounding Electrode Conductor (GEC and the Grounding Electrode (GE) The GE is often a conductor connected within five feet of where a metallic water service pipe enters the premises (IF the water piping is metallic AND a minimum of ten feet buried) or it could be a specific connection to concrete reinforcing bar (a Ufer ground) or a rod of specified material a minimum of eight feet long driven into the earth. This grounding electrode must have a maximum impedance (AC resistance) of less than 25 ohms or else a second grounding electrode may be added with no minimum impedance requirement.

The neutral of a three-wire single phase (or four-wire three phase) service is "bonded" to this earth ground and to the metallic enclosure of the service at this point only. From this single point to all the rest of the electrical installation the neutral and the equipment grounding conductors are NOT connected.

The required depth of conduit depends on several factors. For a feeder from a service to a panelboard the depth is a minimum of 24 inches of cover over the conduit. If this conduit runs under a street or driveway other conditions may come into play.
 
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Old 11-06-13, 04:05 AM
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Well said Furd. Were you up all night typing that?
 
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Old 11-06-13, 06:33 AM
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I am confused between THWN and USE. All I want to know is what wire do I need to buy that handles 200 amps and can be run in Schedule 80 conduit underground? I know it's 4/0 Aluminum or 3/0 Copper but what type? Where do I find it in Quadplex?
This is residential, the required sizes would be 4/0 for aluminum or 2/0 for copper. Like Furd, I also prefer copper, but there is nothing wrong with properly installed and terminated aluminum. If you decide on copper, you should use Type THHN/THWN. If you go with aluminum, you should use Type XHHW which is readily available at supply houses. Type USE is a direct burial single conductor. It would serve no purpose to pay the extra amount for direct burial Type USE conductors when Type XHHW is all that is necessary for a continuous conduit installation. Here is a link to a better description of Type USE.

AL-RHH or RHW or USE

Here is a link to a description of Type XHHW.

XHHW Aluminum

Note that both aluminum conductors have XLP insulation.

Aluminum THHN/THWN and copper XHHW are both available, but usually on special order.
 
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Old 11-06-13, 08:28 PM
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Thank you all for your replies. The water is less muddy.

Furd,
If I understand your response for the grounding I would run a copper wire out from the first panel board to a ground rod that has less than 25 ohms of resistance (or two to grounding rods). I would not attach grounding to my pipes as they are non-metallic. At no point after the first panel board would the neutral and ground ever be connected (and they are only connected together in the first panel board). Correct?
 
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Old 11-06-13, 08:49 PM
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If I understand your response for the grounding I would run a copper wire out from the first panel board to a ground rod that has less than 25 ohms of resistance (or two to grounding rods). I would not attach grounding to my pipes as they are non-metallic. At no point after the first panel board would the neutral and ground ever be connected (and they are only connected together in the first panel board). Correct?
The conductors that provide the low-impedance path to earth are bonded to the utility neutral, the enclosure and the circuit grounds to form your grounding electrode conductor where the first overcurrent protection device is located. If that's in your first panel then you're correct.
 
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Old 11-06-13, 11:50 PM
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Do you have a circuit breaker AT THE METER? If yes, then this is where the neutral, equipment ground and grounding electrode are all bonded together and to the metallic enclosure. Your LOCAL code may also require a grounding electrode (ground rod) at any panel that is in a building detached from the one where the meter and first circuit breaker is installed.
 
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Old 11-07-13, 07:01 AM
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"If I understand your response for the grounding I would run a copper wire out from the first panel board to a ground rod that has less than 25 ohms of resistance (or two to grounding rods). I would not attach grounding to my pipes as they are non-metallic. At no point after the first panel board would the neutral and ground ever be connected (and they are only connected together in the first panel board). Correct?"
Correct.

Local codes determine whether the ground rod wire goes to the meter can or first disconnect(first panel board).
 

Last edited by ray2047; 11-07-13 at 07:48 AM. Reason: Quote formatting.
 

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