It looks promising and is an interesting background read to the idea of backfeeding both legs of the 240v main panel with a 120v gen. But when you add it up, all you get are only two individuals who claim to have done it without any other details or support. Even HB never claims to have done it (successfully or otherwise) himself from what I make of it. Wish there were more support somewhere for this. (see thread https://www.hearth.com/talk/threads/small-invertor-gen-and-subpanel.109909/unread) (message https://www.hearth.com/talk/posts/1450584/)
Meanwhile have shopped around for an interlock device for my old ITE panel and found one for about $50. In line with backfeeding the two 120v legs of the panel with the gen and keeping in mind the idea of not over investing in something that may rarely if ever happen, would like to do this on the cheap but still safely.
One way to keep costs down is to not use the 30a plug on my 120v gen but rather just use the regular 20a duplex socket on the gen with two 12/2 w/ground extension cords (I already have them) and backfeed them to each leg of the panel via the duplex plug on the gen and to a dedicated split outside duplex outlet controlled by the breakers controlled by the interlock -- just break off the junction tab on the duplex receptacle and feed each outlet separately with 12-2 romex from each of the 2 interlocked 120v breakers.
Realize I'd be giving up the full 3000 watt capacity of the gen. But don't really think I need it -- can manage with 2400 watts. All I really want to do is to be able to power (individually, i.e. one thing at most at a time):
1. Side by side ref/freezer an hour or so a day.
2. Small freezer, about the same time, just to get it to zero and keep it closed.
3. Microwave, every now and then.
4. Desktop computer and accessories (this I'd want on almost all the time for convenience but could turn off monitor and a lot of perifs and probably keep use under 200 watts idling -- but could also run for 15 minute or so stretches on battery backup if necessary.
5. Also on almost all the time:
a. a few cfl's
b. a fan in winter for the blower on the insert (though not required)
c. in summer a small fan for cooling
Gas (propane) will handle cooking on stove or outside grill, DHW, HW Boiler (which am not planning on using since insert will heat house and boiler requires elec to run for power vent, ignition, and circulator).
Cost for the equipment:
1. $50 for interlock
2. $10 for outside receptacle, weather proof box, and less than 10 ft 12-2 romex. (I think I have all of these)
3. $5 for making up the short male/male cords for plugging extension cords into outside box (probably have parts also).
These (item 3) are the most controversial (potentially unsafe) unless they could be devised to lock into the outside outlet and could only be unplugged from the extension cord side or care needs to be taken in preventing them from being unplugged from the house side while the gen is in operation (to prevent an unplugged but hot male plug). At a minimum they could be taped to the outside outlet along with a warning tag limiting unplugging from the running gen to only expose a hot female outlet on the extension cords.
The total cost outlay would be for the $50 interlock and maybe some other minor items.
The problem with using the 30a gen power is the cost of the supply cord $50 for made up cords or even making them up as the male and female's are each close to $20, and the input box and receptacle are about $50 plus 10-3 romex.
All of the 240v circuits would be kept off as well as any multi wire 120v circuits -- there are a couple of them -- though with all of the latter 20a 12-3 romex and gen max at 20a not a risk of more than 20a on a neutral.
And also thinking about, after drilling the holes in the panel cover and installing the interlock, leaving it off and only installing it in the event of a power failure. Also leaving the wires for the outside gen outlets unconnected in the panel but wirenutted and labeled. So I could still use those breakers as normal most of the time. They are for a multi wire 120v circuit.
The reason for doing this rather than use extension cords run from the gen to devices in the house, is the convenience of being able to use just about any 120v device without having to separately unplug it from the house and reconnect to the gen and not need such long extension cords or have them running all over the house
Questions:
1. Will it work?
2. How will the gen distribute the 20a between the two legs on the house panel -- on a demand basis up to 20a total, or split it 10a each, or something else?
3. What am I missing here?
