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We have a 200 amp service with the main disconnect on the meter pole outside. We will be rewiring the entire mobile home with a new breaker box but in stages, with the old panel being a subpanel until the wiring is complete.

Would it be better to run a new feeder from the main disconnect to the new box and connect the old one via a subfeed lug (to eliminate the old feeder) or to connect the new box to the main disconnect via a subfeed lug? I'm assuming that if we connect the old panel to the new one via a subfeed lug we'll need to run it underground between the two.

Both the new and old panels will be/are 200 amps. We don't know what the current feeder is which is why we are planning on eventually removing that as well, unless we can figure out what it is.

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You're better off re-routing the feeder to the new box, and then running power to the original box as a subpanel.

The reason is subfeed lugs are costly or unavailable. The only panels that come with them only have 4-12 spaces. So you'd need to buy one that mounts in breaker spaces, and they're not even made for most panels, and very expensive for the panels they are made for. Note that it is not safe to cross brands of breaker, so don't go thinking a Square D "HOM" subfeed lug kit will be your solution for a GE or BR panel that doesn't offer them.

So what do you do instead? Use a regular breaker to feed the old main panel. Something like a 60A breaker (because it's cheap) using 2-2-2-4 aluminum, 4-4-4-6 aluminum or 6-6-6-6 copper SER if the distance is short (because it's cheap). That gets the connection done for $30-50 without the need for costly subfeed lugs.

You may notice 60 < 200. That's true. The fact is, very few of your loads take the vast majority of the power. So relocate 2-3 of your largest loads to the new panel immediately. That's not a lot of work. This time of year I would move over A/C, and water heater. I'd focus on automatic loads you can't control. Most likely, you won't have a problem powering the rest of the house off 60A at this point especially if you are cautious. If you do have a problem, go ahead and move over dryer and range too. And I gather you're not using heaters much this time of year.

All the 120V loads in the house are vanishingly unlikely to trip a 60A breaker. Houses just don't use that much power (other than the 240V loads).

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  • All the 120V loads in the house are vanishingly unlikely to trip a 60A breaker. Unless they're mining or growing!
    – manassehkatz-Moving 2 Codidact
    Commented Jun 30, 2023 at 4:04
  • The new panel will be approximately 20ft from the old one but on the same exterior wall. We've already converted the range to propane so that's not an issue. We could move the water heater circuit to the new panel until we get the tankless propane one installed and move the dryer to it as well. The AC I'm not sure about because it's done oddly. It's wired to a 60 amp circuit and another one. Could a bigger breaker like a 100 amp and wire be used for just the AC and the 120v loads? The AC will be getting replaced by mini splits eventually
    – dgduhon
    Commented Jun 30, 2023 at 6:53
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    @dgduhon ask a whole new question about the AC unit and be sure to include a clear, focused, readable picture of all the labeling on all the units involved with the AC and the brand/model numbers.
    – FreeMan
    Commented Jun 30, 2023 at 12:22
  • @dggduhon sure. Gas furnaces take 120V breaker (for the air handler). North American A/C units are designed to have a large 240V breaker for the outdoor unit, then use the furnace's blower to push air around. If there isn't a gas furnace installed, they install a 120V "air handler unit" = gas furnace without the furnace part :) You can leave the air handler in the original panel for now. But yes, you could go #2 aluminum/90A breaker or #1 aluminum/100A breaker. I only picked 60A because it's $30 cheaper than a 90A :)
    – Harper - Reinstate Monica
    Commented Jun 30, 2023 at 18:00

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