Backup Power for the House Using RV Equipment

[ctechbob]

Since I have around 5000 watts of generator at my disposal (My two inverter generators can be paralleled) I decided it was time to add some backup capability to the house. The downside is that I don't have 240v available from the generator, so I can't just add a transfer switch and power the entire panel. That would be nice, as I could then have hot water since my heat pump water heater draws so little current. In a pinch, we can always use propane and shower in the RV if power is out that long.

The solution is a breakout panel from Reliance Controls that allows you to break out and power separate circuits in the house. I used it to power 120v circuits only, but you can use them to power 240v ones if you have that available. The model I bought on sale from Amazon was a 6-circuit model (2 of 6 Circuits were configured for 240v, but those can be easily separated into 2-120v circuits.)

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Note: Reliance Controls makes about 60 different configurations of the 6 and 10-circuit boxes. All the same basic box, just different breakers and 240/120v configurations and input methods.

I chose to order a 30a RV-style twist lock connector identical to the one that comes on 30a RV's. This way I can just re-use the cables I already have. You simply have to wire both 'hot' legs of the transfer box into the hot leg of the 30amp cord.

I chose to power up basically the entire bedroom end of the house and living room. I have a 110v air conditioner in my master bedroom, so we can cool that end of the house if needed. I also powered the kitchen/fridge circuit. The freezer in the garage gets an extension cord, as does the septic pump, although with as short as our outages usually are, those are completely optional.

 

[Wayne]

I've never heard of such a box! Very cool.

I assume you still have to isolate the house with the breaker panel disconnect, so you don't backfeed the utility and zap a lineman?

 

[ctechbob]

I've never heard of such a box! Very cool.

I assume you still have to isolate the house with the breaker panel disconnect, so you don't backfeed the utility and zap a lineman?

Nope. The circuit gets broken at the new panel so once you flip from line to generator it is completely isolated from the main feed.

 

[Wayne]

Nope. The circuit gets broken at the new panel so once you flip from line to generator it is completely isolated from the main feed.

Ah, so the circuit is wired only to this new box and there is a feed from the main panel to the box that feeds all of the circuits. When an individual switch is flipped, it disconnects the main feed and connects it to the generator feed. Very cool.

 

[ctechbob]

Sort of.

Each circuit is still completely separate.

You come out of each single-circuit house breaker into a wire that goes to the switch panel. When the switch is in 'line' position it just passes that current right back out of the switch to the existing house wiring.

When you flip to the generator, it breaks the connection from the house box, and ties that hot line to the generator bus through the onboard breaker.

Then there's a master neutral and ground that just ties the generator into the house panel. There's no master hot from the house panel, it is all done on a single-circuit basis.

Takes a second to wrap your head around, but it is rather simple.

One thing I do give up when running on generator power is the two Arc Fault breakers for my bedrooms. Once you're on generator, those are completely out of circuit, so you don't have arc fault protection on those two legs. I don't particularly care in this case. If we're on generator power, we're going to be at home and if something arcs and causes an issue, I'm going to be there to catch it. Besides, it is all just for emergencies anyway. When we're on utility power, everything operates just as it should.

 

[Azjeff]

I need one of these, my DIY electrical ability ends with changing out a switch or outlet.

 

[ctechbob]

I need one of these, my DIY electrical ability ends with changing out a switch or outlet.

The installation really isn't bad. What you have is a large ground and neutral that goes to the existing panel (there should be empty lugs in there to tie to).

Then there are (In my case, 10 pairs if you buy the bigger box) 6 pairs of red/black wires, labeled ABCDEF. The red goes to the existing breaker in your home panel and the black gets tied to the wire you removed from the existing breaker that goes out to the house circuit.

The only other thing to hook up is the input. They sell the boxes with inputs pre-installed, but mine came without, so I had to drill 4 holes to mount it with, which is why it is slightly crooked.

Other than that, simple install.

 

[Wayne]

Now that I see a diagram, yes the install would be simple.

Question, if you have a switch on "Line" is the breaker in the Reliance box by-passed?

 

[ctechbob]

Now that I see a diagram, yes the install would be simple.

Question, if you have a switch on "Line" is the breaker in the Reliance box by-passed?

Correct. If you have line selected it just passes everything through. Only difference to the house wiring would be that you added about 2 feet to it. Other than that, same same.

 

[Wayne]

Our trailer sits about 100' from our main breaker panel and we have the 240v version of the 8,500 watt Onan commercial generator (white). We just moved to this house, so I don't know how reliable the electricity is, but if I learn it's not almost completely reliable, I'm getting one of these.

 

[ctechbob]

With a 240v genny I'd be tempted to just power the entire panel with a manual transfer switch. Of course, you'd have to go through your breaker panel and disable anything that would put you over the limit when you're running.

 

[spasm3]

With a 240v genny I'd be tempted to just power the entire panel with a manual transfer switch. Of course, you'd have to go through your breaker panel and disable anything that would put you over the limit when you're running.

I have a small 240v genset from Harbor Freight. I backfeed my panel. i ALWAYS cut the mains so i don't power the lines.

My 4375 runs 16hrs on 4 gallons, i run my well pump to fill toilets and take showers ( gas heat and water heat). I leave all the breakers on, i just turn what i don't need off to manage loads. I turn off the furnace to take showers. I keep the well pump off , until i need to fill toilet tanks, shower, or do dishes. I turn off the well pump and furnace to use the cook top. Its easy and fuel efficient and i have lights anywhere in the house i want. Interior lights are all LED.

 

[ctechbob]

I have a small 240v genset from Harbor Freight. I backfeed my panel. i ALWAYS cut the mains so i don't power the lines.

My 4375 runs 16hrs on 4 gallons, i run my well pump to fill toilets and take showers ( gas heat and water heat). I leave all the breakers on, i just turn what i don't need off to manage loads. I turn off the furnace to take showers. I keep the well pump off , until i need to fill toilet tanks, shower, or do dishes. I turn off the well pump and furnace to use the cook top. Its easy and fuel efficient and i have lights anywhere in the house i want. Interior lights are all LED.

If I had 240 available, that's exactly what I would do too, but I'm stuck with 120 only.