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Thread: Questions on manual transfer switches.

  1. #11
    Join Date
    May 2005
    Location
    Richmond, Virginia
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    Quote Originally Posted by qcroanoke View Post
    Most likely a split buss panel.
    I have used the Square DQO2DTI to create a small genny panel section within a QO split bus panel.

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    Code references based on 2005 NEC
    Larry B. Fine
    Master Electrician
    Electrical Contractor
    Richmond, VA

  2. #12
    Join Date
    Aug 2018
    Location
    Virginia
    Posts
    74
    A few things to consider (subject to any local code amendments).

    1. Does the Generator have a floating neutral or bonded neutral? (See Note 1)
    2. You'll want to have a TS complementary to (1) (unswitched neutral for a float and switched neutral if bonded)
    3. You will need to ground the generator if bonded, but can leave it ungrounded on the float.
    4. If the generator has a 120 switch, examine this option in the TS design. (See Note 2)

    Note 1: You can verify this by running a continuity between ground and neutral. No continuity is a float. Continuity is bonded.

    Note 2: The 120 switch parallels the coils, delivering full power to one of the gen's 120 phases. When you hook up the circuits in the TS, consider any loads that might be able to take advantage of this situation, if so inclined. This will take some thought since it is often at odds with load balancing the 120/240 setting, and you'll lose the other phase when switched.

    As for the standard Reliance Controls TS (I have two installed), they don't switch the neutral, so a floating gen is best. And they can't accommodate AFCI/GFCI breakers. For circuits that require AFCI and/or GFCI, you can always replace the first receptacle in the run with an AFCI, GFCI, or AFCI/GFCI as the case may be.

  3. #13
    Join Date
    Feb 2008
    Location
    Texas
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    946
    Quote Originally Posted by ptonsparky View Post
    I’ve used these in the past and they worked well enough. I’m thinking AFCI requirements may have done them in for those of us under the 17.
    That is just a source selection switch, not a breaker. Unless you are modifying the circuit somehow, that wouldn't apply.

  4. #14
    Join Date
    Feb 2008
    Location
    Texas
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    946
    With a manual transfer switch, like mentioned in the second post, you are manually switching from one source to the other on individual circuits. You don't need to lock out everything else because either you are using the POCO or the generator to feed the circuit. Can't do both simultaneously.

  5. #15
    Join Date
    Aug 2018
    Location
    Virginia
    Posts
    74
    Quote Originally Posted by Chamuit View Post
    That is just a source selection switch, not a breaker. Unless you are modifying the circuit somehow, that wouldn't apply.
    Reliance Controls transfers each circuit individually, bypassing the panel breaker and substituting its own breaker. If the panel breaker is an AFCI breaker, that breaker will be bypassed (along with its AFCI protection) when the TS for the selected circuit is toggled. The RC TS uses a single neutral wire for all TS-switched circuits, connected to the SE panel neutral (and back to the TS neutral bar). All circuit returns land on the SE neutral bar. Those sourced from the generator (based on the TS toggle) ride the shared neutral back to the TS panel and back to the generator. There is no way to meter the neutral return from each circuit at the TS (i.e., at the TS breaker for each circuit). If you can't meter the return current for a circuit, you can't use an AFCI breaker in the TS.

    Hence, the only option I'm aware of to maintain code compliance on a circuit requiring AFCI that also uses the RC TS is to install an AFCI receptacle on that circuit.

  6. #16
    Join Date
    Aug 2018
    Location
    Virginia
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    74
    Quote Originally Posted by JPinVA View Post
    The RC TS uses a single neutral wire for all TS-switched circuits, connected to the SE panel neutral (and back to the TS neutral bar).
    Correction: There is no TS neutral bar. The neutral connects directly back through the TS to the generator.

  7. #17
    Join Date
    Feb 2008
    Location
    Texas
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    946
    Quote Originally Posted by JPinVA View Post
    Reliance Controls transfers each circuit ..... install an AFCI receptacle on that circuit.
    You are absolutely right. The only couple I have installed were on panels that did not have AFCI breakers.

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