Help figuring out how to set up home for portable generator

[Semper Fidelis]

Living in a semi-rural area I'm looking into getting a generator and want to wire it inexpensively but also have the option of running anything I want in the house. I'm trying to save money on a portable generator and found an 8000W generator (10KW peak) with a Suburu engine but have a few questions.

I'm going to buy one of these Interlock kits for my breaker box: Generator InterLock Kit

My main breaker has 200A written on it. The 8000W generator I'm looking at has the following output receptacles:

4 x 120V 20 amp, 1 x 120/240V 30 amp

The former owner said he was able to backfeed his generator in through the electric dryer circuit (now being used) and was able to power everything including one of the two AC units. If all I'm feeding is 30A into the the house with the generator through the interlock then it seems like I wouldn't have the amperage to cover all of my appliances at once but is it reasonable to assume I could cut power to appliances and then turn them on as I needed them as long as I wasn't running all of them at once?

 

[VictorBravo]

First of all, I assume you are not going to back feed and will use the interlock kit. Just a point of info, in most jurisdictions, back feeding is a severe code violation. The main danger is that if you forget to turn off the main, the service wires will be live. During a storm, while repair crews are out de-energizing circuits, they may assume your service is dead and could be in for a severe surprise.

As for rationing power to critical appliances, that is pretty much the name of the game with a light generator. For example, you would not use an electric range or baseboard heaters (they would consume all of the 30 Amps). You probably want to run your lights and maybe a few outlets for convenience to charge cellphones, run a computer (preferably a laptop or a computer hooked to a UPS and a very good filter--generator output is less stable than utility output).

It's basically a matter of adding up the watts you are consuming and figuring the Amp draw. Being an engineer, I'm sure you can figure that pretty easily (Watts/Volts = Amps).

The interlock I last installed had six 15 Amp circuits which corresponded to 2 light circuits, 3 outlet circuits, and the gas furnace. We also had 30 Amps input. If it was cold and we needed the furnace to blow, that meant that we only used one light circuit and allowed the refrigerator and freezer circuit to remain live. The furnace drew 12 Amps on startup, the refrigerator and freezer, both running drew about 10 amps, and that left 8 Amps for some lights (about 400 watts to be conservative for surges).

If we needed more power for something else, the furnace had to be shut down.

Same scenario for A/C. Depending on what they are, if they are running, they might use up more than half of your power.

 

[Mushroom]

You'll just have to do the math to determine the amps you're wanting to use and keep it under 30 for that circuit. Watts / volts = amps. You could run some more things, up to 20 amps, with an extension cord to the other circuit. Not everything at once, but enough to stay comfortable. I'd recommend buying a dual feul conversion kit so you can run the thing on propane, and buy a 100 lbs. tank for $100 at Lowes, if you don't already have tanks (or even if you do if running a line from them is more than you want to mess with). Gas with corn squeezin's goes bad fast even with Sta-Bil (3 mo. max), and when the power goes down the gas stations might be down, too. A 100 lbs tank will run you for a few days.

 

[VictorBravo]

Rich, in reading my first response, I think I might come across as being overly alarmist. I see clearly that you are using the interlock and, from that, I can tell you have been researching this well and are concerned for safety.

I was just unnerved at what was previously done: back feeding through the dryer outlet. So I went all safety Nazi.

Also, just to clarify, you would probably only use the 30A 220 outlet to feed into the house. No doubt you have seen the proper extension cords for that connection to the interlock.

 

[Semper Fidelis]

Rich, in reading my first response, I think I might come across as being overly alarmist. I see clearly that you are using the interlock and, from that, I can tell you have been researching this well and are concerned for safety.

I was just unnerved at what was previously done: back feeding through the dryer outlet. So I went all safety Nazi.

Also, just to clarify, you would probably only use the 30A 220 outlet to feed into the house. No doubt you have seen the proper extension cords for that connection to the interlock.

No worries Vic. He didn't quite have it as a backfeed but had to make sure the main to the grid was cut off when he would plug in the generator. It probably wasn't the safest way to do it.

I keep going back and forth on the approach I want to take. I don't really want to have to spend much but all the portable generators that I could reasonably power most of my stuff are limited to 30-50 Amps. I keep reading how some have used their 8KW generators to power the house and wonder how they managed with only a 30A input and I figured they must just flip off big things like the oven or microwave while the AC is running. I'm kind of leaning toward maybe biting the bullet and gettinga 14KW Standby that has a 200A input.

 

[VictorBravo]

Well, I used an 8KW generator for 5 years, averaging about two 12+ hour power failures per year. But then, it was just two of us in a 650 square feet cottage over an unheated basement.

Granted, it was a small house, but when the power went off we would keep the freezer and fridge going, have some lights, and use the propane stove for cooking. We'd cycle the furnace from time to time in winter.

If we wanted to use the microwave, then we'd flip off the power to the freezer and fridge for that period. Then turn them back on. It was sort of a fun challenge, but more like camping than uninterrupted convenience.

Our chest freezer actually was good for a couple of days without power if not opened. The fridge may or may not be critical, depending on what you have in it.

I'd suppose in VA in the summer, AC would be more critical than a house full of lights.

 

[Semper Fidelis]

I'm not against the fun part of the challenge but I'm starting to wonder if it's worth trying to do it that way. The cost for the 14KW standby generator is not significantly more money and it would not only be fully automatic but would run off the propane tank I already have for my house. I guess my dream configuration would be a diesel generator but I can't find one of those that doesn't have an exorbitant price that I simply can't justify. A friend at Church pointed out that Unleaded gas is gone pretty quickly right before and after any big storm.

 

[Semper Fidelis]

By the way, is there any reason why you can't use an RV generator for a home? They seem to have some decent diesel generators for RV's but I don't know if folks tend to use those for homes.