Is this set-up safe? 120v single phase emergency house feed

[Spacecoastz]

Back in 2022 I purchased a 120v 3,500 running watts inverter generator for emergency back-up power. In over twenty years I’ve never had a power outage last more that a few days. I want all of my 120v circuits to be operational (such as lights, refrigerators, and tv). Prior to this I used a supplemental wire system that I installed during home construction, but that only powered a few special (normally dead) outlets, so bathroom and bedroom lights didn’t work, all normal 120v outlets were dead, and I had to run a few inside extension cords.

In order to feed the 30amp four-pin house inlet box, I have a 20" adapter cord that plugs into the inverter generator TT-30 outlet and converts it to a 4-pin twist-lock receptacle, which then will allow me to use a normal 120/240v cord and plug into that 30amp house inlet box. So, all power will be 120v single phase…to all circuits of the house.

Of course, I will turn off all 240v breakers prior to inverter generator usage, and I do have a breaker interlock on my exterior panel. The question I have is… is this safe? I do have a few “shared neutral” situations, but I know exactly where those are, and will avoid using them improperly. Is there any danger in this kind of set-up during a temporary outage? Is there something I’m not considering in this set-up? To date I have not had to use this set-up. Thanks

 

[PCustoms]

In order to feed the 30amp four-pin house inlet box, I have a 20" adapter cord that plugs into the inverter generator TT-30 outlet and converts it to a 4-pin twist-lock receptacle, which then will allow me to use a normal 120/240v cord and plug into that 30amp house inlet box. So, all power will be 120v single phase…to all circuits of the house.

It's been a long day, but

EDIT: never mind

 

[Bert_]

Anything 240v just see's this as 0v, no power. Really the only thing to worry about is circuits that share a neutral.

3500w is only 29A. You would have to try pretty hard to overload a neutral before you overload the generator. Run it and don't worry

 

[micromind]

Provided the house inlet box cannot possibly backed the utility, your set-up is perfectly fine.

No need to turn off the 2 pole 240 volt breakers, the stuff they power simply won't work. No damage.

 

[theoldwizard1]

Of course, I will turn off all 240v breakers prior to inverter generator usage, and I do have a breaker interlock on my exterior panel. The question I have is… is this safe? I do have a few “shared neutral” situations, but I know exactly where those are, and will avoid using them improperly. Is there any danger in this kind of set-up during a temporary outage?

Effectively you are connecting L1 to L2. This means any 240V appliance will see ZERO VOLTS !

With the interlock, it is safe ! Worst case, you will trip the breaker at the generator.

Some where on Benjamin Sahlstrom's YouTube Channel, he did it. (He claims "... my background as an HVACR technician for 10+ years, Master Plumber, & Electrician Apprentice.")

 

[mm08822]

Within the house, only the 120v MWBC neutrals have a chance of overload. Identify which pairs of circuits are MWBC and keep one from each pair off. (Still unlikely this is needed......but you can sleep better.)

Between the power inlet box and generator - that neutral could possibly get overloaded.....it's more likely than within the house. If you have a 4-wire #12 or #10 cord, low/no issue.

Keep your 20" adapter cord to limited access so someone else doesn't mis-use it thinking it is a true adapter.

 

[wyliesdiesels]

agree with previous comments. shouldnt be an issue

 

[Firstram]

This is how we keep the lights on during an outage with a Honda 2200, or 2 when I want to make coffee! Everything works perfectly.

 

[Spacecoastz]

Thanks everyone with your replies. Just wanted to be sure.
And this is what I have as the adapter: https://www.amazon.com/Generator-Adapter-Transfer-Switch-L14-30R/dp/B09PH8RGVD/?tag=atomicindus08-20

 

[Steve W.]

The sparkles have spoken and said it’s ok, but I have a question based on your first post.

“Of course, I will turn off all 240v breakers prior to inverter generator usage, and I do have a breaker interlock on my exterior panel. The question I have is… is this safe? I do have a few “shared neutral” situations, but I know exactly where those are, and will avoid using them improperly. “

Ok, YOU know all about them, but what if you are not there, and have to call home and tell Mrs. Spacecoastz how to do it?

.

 

[sparky 1971]

The sparkles have spoken and said it’s ok, but I have a question based on your first post.

“Of course, I will turn off all 240v breakers prior to inverter generator usage, and I do have a breaker interlock on my exterior panel. The question I have is… is this safe? I do have a few “shared neutral” situations, but I know exactly where those are, and will avoid using them improperly. “

Ok, YOU know all about them, but what if you are not there, and have to call home and tell Mrs. Spacecoastz how to do it?

.

It won't matter if the breakers for the 240 are off or not, they are going to see 0 volts, at most an electric dryer motor will run along with the light and controls without the heating element working, and an electric range light, clock, and controls will work, but it ain't gonna be baking any fish sticks or tater tots. And the interlock makes it fool proof, even if the Mrs. doesn't know what to do and makes a run at it, she can't screw it up. She might not be able to power the house up with the generator if she doesn't know about the interlock, but nobody is going to get hurt other than the OP for not showing her what to do.

 

[sparky 1971]

Within the house, only the 120v MWBC neutrals have a chance of overload. Identify which pairs of circuits are MWBC and keep one from each pair off. (Still unlikely this is needed......but you can sleep better.)

Something about this poster seemed familiar. So I looked and I think that's been done but it seems strange that this is just coming up after a year and a half.

How do I identify multi-wired circuits?

During a power outage, I want to feed my house wiring (both legs) 120V, same phase. On the house I have an four-pin inlet box with breaker (to feed both legs), an interlock device on the panel, and an adapter cord that converts the TT-30 generator outlet to a L14-30 feed. What I'm concerned...

www.garagejournal.com

 

[theoldwizard1]

This is how we keep the lights on during an outage with a Honda 2200, or 2 when I want to make coffee! Everything works perfectly.

Kind of strange, but you CAN wire one 120V generator to L1 and a different one to L2 and as long as you turn off the breKers for all 240V circuits nothing bad will happen.

 

[Firstram]

Kind of strange, but you CAN wire one 120V generator to L1 and a different one to L2 and as long as you turn off the breKers for all 240V circuits nothing bad will happen.

Which is what we do with a little put-put, feed both legs of the panel through an interlock. Ceiling fans, TV, LED lights, refrigerator and upright freezer only draw a little over 8 amps!

 

[theoldwizard1]

Which is what we do with a little put-put, feed both legs of the panel through an interlock. Ceiling fans, TV, LED lights, refrigerator and upright freezer only draw a little over 8 amps!

Segue - I was at HF the other day and was looking for an item. As you all know, there are very few employees around so I went over near one who was talking to a lady about a generator. He was doing a good job, but she had that "glazed" look. She finally said, "I just want to run my refrigerator and freezer, charge my phone and run a few lights." He quickly shifted from the 5kW model to the 3kW model. Then she said, "So I can plug each in for a couple of hours and then unplug and plug in the next one ?"

I jumped in and said, "If you are going to swap plugs (loads) around, then you only need the 2kW one." Employee concurred.

 

[Spacecoastz]

So again, thanks for the replies and responses. And yes Sparky, this was my plan about two years ago, but like I said I haven't had any reason to use it and as my OCD surfaces (we are in hurricane season in Florida) I just wanted to re-check and be sure that this is a safe situation. During power outages I have always used a secondary wiring system, independent of the main house wiring, so this is still new to me.

Steve W asked a question about the shared neutral circuits and yes my wife will be briefed again during any generator usage not to use the air fryer or dishwasher if I'm not home. And if I'm not home the generator probably won't be running anyway.

Ironically when I first research this idea of just using 120v and having a modest inverter/generator, I didn't even know about "shared neutrals". Sparky and others were very helpful during my original post, and in that process I discovered that all four of my shared neutrals were on the same phase. All eight circuits use an individual thin-style breaker and the original electrician placed those breakers in the panel off by one position. So for 22 years those shared neutrals were on the same phase. That has since been fixed.

 

[pima67]

Don't just brief her but also write up and post specific instructions. May help you too in the future.

 

[Spacecoastz]

I did that back when I fixed the shared neutral circuits.