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Generator with no transfer switch? Just a manual plug?


RichTJ99's Avatar
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09-08-12, 12:35 PM   #1 (permalink)  
Generator with no transfer switch? Just a manual plug?

Hi,

I am in the market for a cheap generator solution. My plan is to get a full house propane generator next year (or two) but I dont have the money this year for that. I live in an area that frequently loses power.

With that being said I am aiming to get a portable generator (probably the honeywell 7500 at costco - Costco - Honeywell 7500W Portable Generator) with the intention of it powering my well pump & the oil furnace.

I have a few questions, specifically how do I find out how many amps I need?

My friend has a honda generator, he hooked his up using a long extension cord with one end plugged into the generator, the other end plugged into a circuit breaker that is plugged into his fuse box. He then turns off the main to his house, runs off his generator as needed.

Basically any time his power turns off, he shuts the main, plugs in the breaker (connected to the generator), starts the generator & thats pretty much it until the power comes back on at his neighboors. At which point he shuts his generator off, unplugs the generator circuit, then turns his main back on.

I realize this is probably a pain in the butt to do each time the power goes out but is this an acceptable way to do it? I am looking for a temporary solution with a temporary generator that I will sell once I have the full house propane one (which will have an auto transfer switch, etc).

Any feedback would be appreciated.

Thanks,
Rich

 
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09-08-12, 01:04 PM   #2 (permalink)  
My friend has a honda generator, he hooked his up using a long extension cord with one end plugged into the generator, the other end plugged into a circuit breaker that is plugged into his fuse box. He then turns off the main to his house, runs off his generator as needed.
He could kill someone. You must have an aproved interlock or a transfer switch.

I realize this is probably a pain in the butt to do each time the power goes out but is this an acceptable way to do it?
NEVER permissible! Do yourself and your buddy a favor. Don't do it. He is going to need a friend to bail him out of jail if he keeps doing it the way he is doing it. Bet he's using a suicide cord also.


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09-08-12, 01:40 PM   #3 (permalink)  
Welcome to our forums Rich!

The idea of generator back-feeding is probably new to you but we see this question quite often and need to warn you that it is a very contentious topic amongst trade pros.

The whole idea of someone powering up an electrical panel with a generator where a wrong move could back-feed power into the network is a danger no one should be exposed to.
Plus, the risk they take with a suicide cord which is a male plug wire to be energized places them or any innocent person nearby at risk.
I can imaging a power failure where the designer of a killer gen hook-up explains to their spouse or kid how to hook it up when the lights go out.

The pros will have suggestions for you to safely do this so stay tuned and perhaps your friend might gain some info to convince him to undo what he has done.


GregH.........HVAC/R Tech

 
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09-08-12, 02:03 PM   #4 (permalink)  
Electricity is unforgiving and humans make mistakes.

Yes, doing this & flipping that can work but it's inviting injury or death. If you electrocute yourself it might make the Darwin list but if you screw-up just once and back feed power to the lines exiting your house you could injure or kill the guy trying to restore your power which nobody wants. There is a reason connections like that are not permitted and people face charges after the storm. It's just too easy for one human mistake to hurt someone.

 
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09-08-12, 02:36 PM   #5 (permalink)  
I am looking for a temporary solution with a temporary generator that I will sell once I have the full house propane one (which will have an auto transfer switch, etc).
Rich, to safely backfeed power from a generator to some (or all) of the loads in your house requires an inlet for the generator to be connected to, a permit and inspection from the AHJ (Authority Having Jurisdiction), and one of the following:
  • a transfer switch (manual or automatic);
  • an emergency power panel with a built-in transfer switch and the critical loads in it; or
  • an approved interlock system built into the main panel.

 
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09-08-12, 02:37 PM   #6 (permalink)  
Your best and cheapest option is to install a transfer switch such as this:



which allows you to pre-select certain loads and safely transfer them to generator as needed. These go for about $150-250, depending on the number of circuits you need. They can also be wired to a remote inlet on the side of the house, so you don't have to run the generator cord inside. You could even leave the generator permanently plugged into it and add a remote starter if you like (that gen is electric start already, and remote starter units are fairly inexpensive)

The "C-D" switches are tied together for use with a 240v load, but if you have all 120v loads you can remove the tie and use it for two separate circuits.

 
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09-14-12, 07:56 PM   #7 (permalink)  
Some Navy guys could back me up on this, but I heard from an instructor that was in the navy that if they did not "line up" the phasing right with the ships generators when bringing another on-line, they would go BOOM! and shut down the power on the entire ship.


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09-14-12, 08:13 PM   #8 (permalink)  
Some Navy guys could back me up on this, but I heard from an instructor that was in the navy that if they did not "line up" the phasing right with the ships generators when bringing another on-line, they would go BOOM! and shut down the power on the entire ship.
That was likely many thousands of amps, rather than the 30A that a little portable put out...do you happen to have any sort of videos of that happening, Tolyn?

And to add to what others have said, backfeeding a panel without a listed transfer switch or interlock is begging to kill a lineman, friend, or family member.

 
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09-14-12, 08:41 PM   #9 (permalink)  
I heard from an instructor that was in the navy that if they did not "line up" the phasing right with the ships generators when bringing another on-line, they would go BOOM! and shut down the power on the entire ship.
That rings true. I remember when the POCO energized the gear for a water heater plant I was working on and we could hear the BOOM! when the crossed phases hit in the gear out on the dock, as far as you could get from the gear room and still be in the building. The linemen could hear it too, and the pole where they closed the feeds was probably 1/4 mi. away. They went to get some lunch and change shorts while we straightened out the connections in the gear.

But that's about crossed phases. It made a scary noise and cost us maybe an hour for 2 or 3 guys to straighten out the connections. The OCPDs on the pole did their thing, no one was hurt, and all equipment was protected. We were online and bringing up sub-feeds for at least a couple of hours before beer:thirty.

That is not the same as a backfeed. There was no power that could be fed back on the POCO system A backfeed is dangerous in a life-threatening way. A phase bump is just sound-and-light.


Last edited by Nashkat1; 09-14-12 at 09:06 PM.
 
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09-14-12, 08:44 PM   #10 (permalink)  
No videos, just shop talk. Likely before youtube was invented.


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09-14-12, 08:46 PM   #11 (permalink)  
Likely not thousands, but still a lot more than the 30A clash we're talking about here. I have a very hard time believing even a 100A clash (with the same multiple breaker protection) would do that kind of damage. The dead giveaway that he's full of it is that he claims the SE melted the aluminum siding.

Again I'm not in any way implying that backfeeding isn't totally wrong, dangerous, and illegal, but don't tell lies.

 
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09-17-12, 06:30 AM   #12 (permalink)  
The cheapest and easiest method if legal in your area is a lockout plate (can't remember the correct name).
You can get a plate that matches your breaker pannel and will only allow the main on (grid power), or a 220V breaker on (your generator feed).
You're looking at probably less then $100 for the plate and a 30A (or suitable for your generator) breaker.

If you go this route, all you do is flip your main off, slide the lockout over, and turn your generator feed on. Make sure to turn all other breakers off except for the ones you want to power. Your generator probably won't have the power to run everything.

Keep in mind, this is legal in some areas, and not others, so double check first.

 
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09-17-12, 03:51 PM   #13 (permalink)  
Add-on interlock plates are not legal or approved anywhere because they can be defeated by simply removing the dead-front. The only approved interlock plates come installed from the factory.

 
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09-18-12, 10:06 AM   #14 (permalink)  
Alternative: Don't connect the generator to the home electrical system. Instead use extension cords (preferable the fat orange kind), unmodified, to plug in individual lights and appliances directly using the generator's receptacles.

For a "hard wired" item such as a furnace, install a junction box somewhere along its branch circuit. In that box install one 3 way switch with the common terminal connected to the load wire, one traveler terminal connected to the feed wire, and the other traveler terminal connected to a male receptacle also installed in the box. The end of an orange extension cord fits onto the male receptacle for connecting to the generator.

Now you did mention eventually installing a permanent generator with auto-transfer switch. You could install the transfer switch now and connect the temporary generator to that.

Mod Note: Best to use a single circuit transfer switch intended for a furnace. Above will only work on 120 volts and switch would need to be motor rated. and certified "break before make". Your average three way switch does not usually meet those requirements as far as I know.


Last edited by ray2047; 09-18-12 at 05:12 PM.
 
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09-18-12, 02:57 PM   #15 (permalink)  
AllanJ, Your advice is contrary to code. Although it may work in theory, the OP should be and was advised to do it correctly with a transfer switch set up.

 
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09-18-12, 03:57 PM   #16 (permalink)  
Allan, what you suggest will immediately trip the gfci on a generator.

 
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09-19-12, 01:45 PM   #17 (permalink)  
No it won't. Doesn't change that it's wrong, but theres nothing that would cause the GFCI to trip.

 
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09-19-12, 02:13 PM   #18 (permalink)  
theres nothing that would cause the GFCI to trip
Matt, if I understood what AllanJ was proposing correctly, it was to connect only the hot feed from the generator to a load, and not complete the circuit. If that didn't trip a GFCI, I would replace the GFCI. Immediately. The neutral must also be connected.


Last edited by Nashkat1; 09-20-12 at 09:22 AM. Reason: correct misinformation
 
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09-19-12, 07:47 PM   #19 (permalink)  
No he proposed that the 3 way (SPDT) switch be used to switch the hot leg of the furnace feed between utility and the hot prong of a male receptacle. The neutral and ground from this receptacle would be permanently connected to the circuit. He may not have made it clear but I guarantee you that was his intent. He also did not advocate a suicide cord, he says very clearly that the end of an orange extension cord fits onto the male receptacle.



It's actually among the least dangerous homebrew suggestions I've seen. However it is still a dangerous setup because a standard 3-way switch is not 'break before make'.. That means there is still the possibility - as remote as it is - for there to be a split second connection between utility power and the male receptacle, posing a shock hazard at the male prongs or the possibility of a brief surge from the generator inlet backfeeding out to the transformer - and a brief surge at a transformer secondary can translate into a powerful whack to someone who might be touching the primary.

 
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09-20-12, 09:28 AM   #20 (permalink)  
No he proposed that the 3 way (SPDT) switch be used to switch the hot leg of the furnace feed between utility and the hot prong of a male receptacle.
That's what I said, just in different words.

The neutral and ground from this receptacle would be permanently connected to the circuit. He may not have made it clear but I guarantee you that was his intent.
He didn't. I wanted to edit my post anyway (see next) so I spelled that out at the same time.

He also did not advocate a suicide cord, he says very clearly that the end of an orange extension cord fits onto the male receptacle.
You're right, and I missed that. I've edited my post to take that comment out. I guess I'm just not used to seeing "male receptacle" instead of "inlet."

 
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