L14-30 Generator connection - cap off neutral wire?

Discussion in 'Electrical Forum discussion & Blog' started by Larry5, Sep 18, 2021.

  1. Larry5

    Larry5 New Member

    Joined:
    Sep 18, 2021
    Location:
    PA
    2 part question. I'm looking to do this the 100% correct and safe way, but can't find an answer.

    Part 1. I'm looking to feed my well pump with a generator in power outages. I purchased the Reliance Controls CSR302 manual transfer switch. This unit takes my generator's L14-30 connection; I have the extension cord just for this to plug into the transfer switch. This issue is the wiring, see picture. My well pump has a 220v 3-wire; two hot and ground.

    IMG.jpg

    Per the instructions for the CSR302:
    - the 2 red wires connect to the 2 hot feeds coming from the breaker panel
    - the 2 black wires connect to the two hot feeds going to the well pump
    - the green wire would connect to both grounds (from the panel and to the pump)
    - the white wire ????

    Since the line going to the well pump from the panel doesn't have a neutral, can I just put a cap on the white wire and tape it? Is it that simple?


    Part 2. This kinda depends on the correct way to do part 1. I purchased a second CSR302 to connect it the same way for my Hybrid Heat Pump water heater. The water heater also only has a 220v 3-wire feed. I figure I can plug in the water heat to get it nice and hot; then move the power cable to the water pump. Plenty of hot water to take a couple quick showers. In emergencies remember.

    The added issue here is it's a "heat pump" water heater; incredibly efficient but a byproduct is condensation. So I have a separate little pump on the floor to catch the water dripping. The pump is 110v and only draws 1.5A. Is it possible to tie this into the CSR302?

    I was thinking of mounting a 110 metal outlet box on the bottom side of the CSR302 via a knockout. Power it with tapping off one of the black wires, ground wire, but now feed it the white wire for neutral. Yes, I would have to manually unplug the pump and plug it into this outlet when I'm using the generator.

    Is this possible or just a bad idea from the start?
     
  2. wwhitney

    wwhitney Well-Known Member

    Joined:
    Mar 17, 2019
    Location:
    Berkeley, CA
    [BTW, the standard terminology is to not count the EGC (that's how NM cable is marked), except in flexible cords. So that would be a 240V 2-wire supply.]

    (1) It's quite a bit more complicated.

    The CSR302 is just a DPDT switch with center off position. So it connects the 2 black legs (to the load) to either the 2 red legs (from your electrical panel) or to the flanged inlet (from a generator). And the 3 EGCs all get tied together as you mention.

    Where it gets complicated is whether the generator you are using has a neutral-ground bond on the generator. Every (grounded) electrical system needs to have one neutral-ground bond in it. That way if a hot conductor faults to an equipment case or some other metal connected to the EGC, the circuit is completed through the neutral-ground bond to trip a circuit breaker. Your electrical system from the utility should have one neutral ground bond at the main service panel, and everywhere downstream neutral and ground are separated. You don't want to have two neutral-ground bonds in a system, as that would parallel the EGC with the neutral, putting neutral current on the EGC.

    Now with your generator transfer switch, if the circuit from your electrical panel had a neutral, and the load required a neutral, you'd tie together the 3 neutral conductors: electrical panel, load, and flanged inlet. Then you'd want to only use the transfer switch with a generator without a neutral ground bond, as on generator power, the neutral-ground bond at the service panel would still be part of the system. The transfer switch should get the appropriate warning label that says basically "only for use with generators without a neutral-ground bond".

    However, the circuit from the utility has no neutral. So one option is just to cap the white neutral wire from the flanged inlet. Then while on generator power, the utility side neutral-ground bond is no longer part of the system. That means the generator should have a neutral-ground bond. And the transfer switch should be labeled "only for use with generators with a neutral-ground bond."

    If you would instead prefer to use the transfer switch with generators that don't have a neutral ground bond, then you could make the required neutral ground bond for generator operation at the transfer switch by connecting the white flanged inlet conductor to the 3 EGCS. Then the transfer switch gets a label that says "only for use with generators without a neutral-ground bond." This configuration is only an option because the supply from the utility side has no neutral.

    2) So what is the (amp) rating for the heat pump water heater circuit?

    The CSR302 is only for transferring a single circuit at a time. So you can't transfer the condensate pump and the heat pump water heater if they are on separate circuits.

    A simple way to put them on the same circuit would be to swap out the condensate pump for a 240V only (2-wire) model. Then it would be supplied from the heat pump water heater circuit, possibly with an extra OCPD (fuse or breaker) in between, depending on the ratings. Then you can treat the 240V 2-wire circuit for the heat pump water heater plus condensate pump the same as in (1) above.

    Another way to put them on the same circuit would be to add a neutral from the electrical panel to the heat pump water heater circuit. That would be the hard part, you'd likely have to pull new wire or cable. [Unless the condensate pump is on a dedicated circuit currently, and either that circuit is in the same conduit as the heat pump water heater circuit, or the two circuits are in separate NM cables that follow the same path from the electrical panel to the equipment location; then you could repurpose the existing neutral conductor for the condensate pump to use on the heat pump water heater circuit.]

    Then you can add a 120V receptacle to the heat pump water heater circuit (possibly with OCPD, depending on the ratings) to supply power to the current condensate pump. Now you need to install the CSR302 for a 120V/240V 3-wire circuit, which is covered in the 4th paragraph of part (1). And then if you want to have consistency with the well CSR302 (both require a generator without neutral ground bond), you'd install that one as in the last paragraph of part (1).

    Cheers, Wayne
     
    Last edited: Sep 19, 2021
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  4. Reach4

    Reach4 Well-Known Member

    Joined:
    Sep 25, 2013
    Location:
    IL
    Ideas:

    I might consider running the output of this transfer switch to a subpanel. That would handle the 120 and 24o mix. So how to shift feeding the well vs (WH+condensate pump)? You could turn breakers on and off

    Another idea that comes to mind is to power the pump and WH via a relay (contactor). When the pressure switch calls for water, the relay sends power to the pump. Otherwise power goes to the WH.
     
  5. Larry5

    Larry5 New Member

    Joined:
    Sep 18, 2021
    Location:
    PA

    Thanks. I have the Generac RS5500 which states "Neutral to Ground Bond - YES"

    So based on that, my "Part 1" is easy, just cap the white/neutral wire.

    Part 2. The water heat is an 80 gal GE GeoSprings set in Heat Pump mode and specs say 550W. I never even thought of replacing the condensation pump with a 22v one. Checking it out a 220v one is 75 watts and only 0.5A which I could easily just tie it directly into the water heater wire; then I have no plug to worry about.
     
  6. Reach4

    Reach4 Well-Known Member

    Joined:
    Sep 25, 2013
    Location:
    IL
    I looked at http://www.reliancecontrols.com/Documents/CSR302 Instructions.pdf

    I think the makers of your transfer switch expected an isolated neutral from the generator. Some transfer switches switch the neutral. Yours doesn't.

    Many generators have a way to isolate the neutral. I don't know if yours does.
     
  7. wwhitney

    wwhitney Well-Known Member

    Joined:
    Mar 17, 2019
    Location:
    Berkeley, CA
    Don't forget to label the CSR302 for use only with a generator with neutral-ground bond.

    There's still the question of overcurrent protection. What size breaker is supplying the GE GeoSprings? If it's 30A, and your 240V condensate pump says max OCPD 20A or 15A, then you'll need to add some OCPD between your water heater circuit tap and your 240V condensate pump. Could be a small 2 position panel, a 30A fused disconnect with smaller fuses in it, or a Bussmann STY in a 4" square box with 2 fuses.

    Otherwise, yes.

    Cheers, Wayne
     
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