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I have a transfer switch that connects one of the line sides directly to the main electric meter breaker. The load side of the transfer switch goes to the interior in cement main service panel.

Due to space limitations and distance, I'm thinking of using polaris connectors for the 2 pole lines and neutral from the transfer switch load side (which also goes into the home) to mount a sub panel for a few extra circuits.

The main electric meter breaker, double pole double throw transfer switch, and interior main service panel are 125 Amps. The main cables from the meter are 2 AWG. The ground and neutral are bounded together on the main meter electrical panel.

Would this setup be ok to add a 125 Amp Subpanel on the load side of the transfer switch? I'm concerned with the neutrals in this setup.

  • Does your generator have a bonded neutral (most portables ship this way by default)? Do you want to be able to use it as a portable generator in the future? – ThreePhaseEel Aug 9 '18 at 22:53
  • It states the following in the generator manual. "This electric generator comes with the neutral wire already bonded to the frame. If the bonding wire is removed then the GFCI receptacles will no longer function as designed. If the neutral bonding wire is removed to accommodate a transfer switch installation for connection to a house or building, then the transfer switch must not switch off the neutral connection to ground within the building." – Rick Aug 9 '18 at 23:01
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    If that's the case I would just need to disconnect the neutral wire from the frame when connecting to the transfer switch. Correct? – Rick Aug 9 '18 at 23:03
  • yeah, but having to switch the generator back and forth between the two configurations can be...fiddly, from what I can tell, which is why I ask if you want to be able to use the generator as a portable still – ThreePhaseEel Aug 9 '18 at 23:23
  • My generator's main use are for power outages which are common where I live. – Rick Aug 9 '18 at 23:26
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Go ahead and do that

A subpanel downstream from a transfer switch is generally an expected thing to have in a standby power system. 125A is a fine size for such (since you likely aren't going to be putting nearly that much load on the standby system), and a 24 or 30 space unit would be not at all out of place here, either.

As to neutrals? It's the transfer switch's job to deal with any neutral shenanigans that may be going on. Since you are using your generator mainly for backup, I'd pull the neutral bond and put a clearly visible, indelible label on it saying that the bond was pulled and referring to the correct section of the manual to reinstall it if I were in your shoes, by the way -- this means you can have a solidly bonded neutral in your transfer switch, which makes life far easier when it comes to transfer switch selection.

  • Just to clarify, it shouldn't be an overload if both the main interior service panel and new subpanel be connected to the load side of the transfer switch, using 3 polaris insulated splice connectors, and switched to utility side using 2 AWG wire? – Rick Aug 10 '18 at 1:37
  • @Rick -- WHY are you trying to transfer the whole blasted house? When things are dark, hot, and sticky because the power's out, you don't want to be fumbling around trying to read the labeling to figure out which breakers to throw to avoid overloading the generator before you transfer power... – ThreePhaseEel Aug 10 '18 at 2:01
  • Before switching to generator line on the transfer switch I'll turn off most of the breakers off anyways. – Rick Aug 10 '18 at 2:46
  • @Rick -- that's the thing -- do you want to be fumbling around in the dark, turning off breakers, when the power goes out for real? – ThreePhaseEel Aug 10 '18 at 2:47
  • I'd have to do it anyways to setup the generator. – Rick Aug 10 '18 at 2:49

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