In 1992 Cutler Hammer panels did not have a means to separate the grounds and neutrals on the panel. My electrician says he never seen a panel like this before. We want to install a whole house generator with 200 amp circuit. Is there a modification that can be done or do we have to install a new panel? The current panel 200 amp Cutler Hammer.

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    Can you give us a model number for the panel? Also, why do you want to install a generator for the whole house, instead of splitting the standby loads off into their own subpanel which can be transferred without having to deal with service-entrance rated hardware? – ThreePhaseEel Nov 24 '18 at 15:37
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    CH is a top panel, claims of its inferiority are dubious. I have two of them almost 50 years old that provide for separating grounds and neutrals. What he means is "I do not realize I need to go out and spend money on an accessory ground bar for this panel". I guarantee you the mounting holes are there. – Harper - Reinstate Monica Nov 24 '18 at 16:35
  • Sorry forgot to mention the generator comes with internal Main Circuit Breaker and 200 amp T.S. – Don Nov 26 '18 at 19:36
  • @Don -- I take it the transfer switch it comes with is an automatic transfer switch? – ThreePhaseEel Nov 28 '18 at 23:57

Separating neutral and ground on a Cutler Hammer panel is as simple as installing an accessory ground bar. They sell those (now under the Eaton brand, but still marketed as CH or BR) and the panel should have holes already drilled and tapped for the mounting screws that are in the kit.

If for some reason yours does not have mounting holes that line up with screws on standard ground bars for your panel, you can physically mount it some other way that reflects good workmanship (NEC 110.12).

I am not the biggest fan of screws as a method to make electrical connections, so if the panel's metal chassis figures into grounding anythingv(like metal conduit leaving the panel), I recommend a burly grounding strap from ground bar to panel chassis, separate from the mounting screws.

Lastly, remove the grounding screw or strap from the neutral bar. Right now the neutral is grounded to panel chassis, and you no longer want that.

Occam's Razor: install a subpanel

There's a better and less disruptive way to do all this. You can fit a proper subpanel next to your main panel. You then move the circuits you want supported from generator, into that subpanel.

If the generator is permanently installed and not GFCI, remove its neutral-ground bond and use some ingenious generator interlock hardware made by actual tier 1 panel maufacturers (so you're not paying top dollar for hacked up rubbish like Reliance switches). For instance a Siemens 16-space "subpanel as transfer switch" costs about $130 and is top shelf.

If you want to use a portable generator that you will be hauling away to other tasks, you will need to switch neutral. The same principle applies, but you put the 3-pole transfer switch immediately next to the subpanel.

  • An Eaton GBK21 will do the trick (his panel is CH, btw) – ThreePhaseEel Nov 28 '18 at 23:58

A separate generator panel is readily available from the home centers. This will work with your existing panel. Match the breaker and panel capacity to the output of your generator.

  • He may want an ATS -- not that you can't do an ATS for a subpanel, but I wouldn't lock him into borg selection here either. – ThreePhaseEel Nov 24 '18 at 17:49

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