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    cmkruse's Avatar
    cmkruse Posts: 1, Reputation: 1
    New Member
     
    #1

    Mar 7, 2014, 09:51 PM
    Service entrance cable.
    What is the proper size SER cable to run from the meter panel (with 200 amp breaker disconnect) to the inside breaker panel (150 amp). Is it 4/0 4/0 2/0 (three conductor) or is it 4/0 4/0 4/0 2/0 (four conductor)? I'll have the whole installation inspected by a licensed electrician before calling the city but wanted to make sure this meets new code before going forward.

    Thanks
    donf's Avatar
    donf Posts: 5,679, Reputation: 582
    Printers & Electronics Expert
     
    #2

    Mar 8, 2014, 06:07 AM
    I don't understand your question. Is your service going to be 200 Amp or 150 Amp?

    Personally, if you are going to have POCO bring 200 amp to you, why would you step down to 150, use the 200 Amp.

    As to the cables. PCOC will use a 4/0 three wire cable to bring the service to your meter. Now, If the meter is going to serve as a "Main Disconnect" switch, then you must use a four wire cable from the disconnect switch to the distribution panelboard.

    Now the cable from the disconnect switch is determined from NEC (2011) Table 310.15(B)(16). You need to know the temperature of the connections of both the disconnect switch and the distribution panelboard. If either device is rated at 60(C), then column #1 (Aluminum) must be used. Which results in a 4/0 AWG cable size for 150 Amps. If you use 200 Amp, then you need a 350 kcmil cable. Again, you would be smarter to wire for the 200 Amp service even though you are only getting 150 Amp. This will allow you to use the same cable if you should decide to go to 200 amp at a future time.

    However, if both the disconnect switch and the distribution panelboard are listed for 75(C) then the conductor size is determined from column #2 (center) Aluminum column. For 150 Amp, use a #3/0 AWG cable. For 200 Amp use a 250 kcmil cable.

    Be careful here. Because you are using a "Main Disconnect" switch, Neutral and Ground must be bonded together at the disconnect switch. At the distribution panelboard, Neutral and Ground cannot be bonded. Neutral must be isolated from Ground.
    stanfortyman's Avatar
    stanfortyman Posts: 5,598, Reputation: 279
    Electrical & Lighting Expert
     
    #3

    Mar 8, 2014, 06:27 AM
    Don, Don, Don. You are way over thinking this.

    He is asking about SER. This is the proper cable from an outside disconnect to an inside panel.
    Since we can assume this is for a residential application, and we can also assume this is for the main panel <"from the meter panel (with 200 amp breaker disconnect) to the inside breaker panel">, we would use the table for sizing residential service entrance.
    This would be 4/0AL or 2/0CU for a 200A service, which this is. Worrying about the temperature of the terminations is not even worth the effort.

    cmkruse, I'll also ask, why a 150A panel off a 200A disconnect?
    donf's Avatar
    donf Posts: 5,679, Reputation: 582
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    #4

    Mar 8, 2014, 07:02 AM
    Stan,

    Good morning. My over thinking was caused by the "Breaker at the meter".. I took that to be a "Main Disconnect" are you saying that that would not be true?

    If there is a main disconnect switch, don't we have to use a 4 wire feed from the switch to the panel?
    stanfortyman's Avatar
    stanfortyman Posts: 5,598, Reputation: 279
    Electrical & Lighting Expert
     
    #5

    Mar 8, 2014, 07:20 AM
    Yes, that's how I took it too. That there is a main breaker/disconnect at the meter. This is why he is asking about SER cable. SER has two (sometimes 3) hots, a neutral and a ground.

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