We just got our power back from the hurricane and I have a genertor question. I used a 5000 watt generator during the outage and ran extension cords to the refrigerator, freezer, a floor lamp, TV and a fan. A neighbor has rigged up his breaker box in such a way that he runs power from a small generator the same size as mine to the 115V side of the panel and has installed a plug to make the connection quick and easy. He turns off the main breaker to prevent backfeeding into the power lines. With this arrangement, all the 115V circuits in the house are powered by the generator (none of the 230V) and he says everything is safe, just be careful not to turn on too much stuff at once and overload the generator. My question is, is this a safe installation and is it permitted by code?
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Replies
"My question is, is this a safe installation and is it permitted by code?"
ABSOLUTLEY NOT!
MANY, MANY, MANY PROBLEMS.
For a more detailed explaination go a search on backfeeding.
I know the direct plug in is a death trap ..
but ... are there transfer switches that'd work with the smaller/portable generators?
Jeff Buck Construction
Artistry In Carpentry
Pittsburgh Pa
Yes there is
I have a 6 circuit transfer box wired in for mine
forgot who makes it though
I installed a 6 circuit box from Reliance for my 6600 watt generator. Took longer to patch the drywall than it did to connect the transfer switch. Beats the heck out of running extension cords all over the place...
Terry
I installed a transfer switch for a small(10KW) generator once. It was a little manual one made by Square D. It is basically a sub-panel that is fed by both the Main and by the Generator. It has an mechanical interlock mechanism that prevents both mains from being on at the same time, thus preventing any feedback to the utility.
Because the loads in the sub-panel are selected specifically for emergency use, you can prevent overloading the generator by only feeding loads from that panel that the generator can handle.
In case of power failure, the owner would start the generator, plug in to male receptacle on the outside of the house, (or the generator could be hard wired), go to the transfer switch and turn off the main from the utility and on the main from the gen.
There are several codes that apply to this arrangement, so I would recommend that an electrician is at least consulted before any installationIf you haven't drawn blood today, you haven't done anything.
"are there transfer switches that'd work with the smaller/portable generators?"Yes, they are called extension cords.Seriouly there are small 4-6 circuits transfer switches that would work.But you have to worry about the load. For something like a 2500 watt generator the extension cord is probably the best.
Bill's answer is correct, but short.
Some of the background is that unless you have a proper generator tie-in with disconnect, you may by electrocuting lineman as you attempt to keep the ice cream frozen.
A proper generator connection has a double-throw switch which can ONLY connect your house to the grid OR your house to the generator and NEVER connect the grid to the generator.
Or, you can plug the individual appliances into the generator like you did and that is safe. (If you keep the generator outside the house, etc.)
Note that I have serious doubts that improperly connecting a generator will automatically kill lineman. Yes, lineman are good, lineman are our friends, and my dear Uncle Bill was a lineman. BUT, no one has explained to me how a 5000-watt generator can bring the whole grid up to 120 volts (or the high-tension lines up to thousands of volts) without turning on every light, and fridge, and toaster in town. And 5000 watts can't do that.
So we have to have some pretty specific conditions to actually fry someone. 1) you have to connect your generator through the house wiring to the grid (and your neighbor's concept, WHEN DONE CORRECTLY, wouldn't), 2) your house or a very few others have to isolated from the grid (because otherwise the huge load would drag down your generator), 3) a lineman has to be working on individual conductors on your service (rather than throwing a disconnect miles away), 4) said lineman has to be in contact with a conductor and ground or neutral (a practice I avoid myself), 5) the lineman also has to grab hold of, in uninsulated hands, a possibly active conductor which he/she didn't check for voltage, and 6) the aforementioned foolish and unlucky lineman must touch that conductor and neutral/ground so that the current passes through his/her chest (i.e. one in each hand or one in a hand and one in an uninsulated foot, etc).
What you did is safe and "to code" (in that codes don't cover temporary power sources and temporary wiring).
What your neighbor did was safe IF done correctly and carefully. But it is definitely NOT to code.
There is also the problem that it appears that half the circuits are backfeeded through a 240v load.
"Note that I have serious doubts that improperly connecting a generator will automatically kill lineman. Yes, lineman are good, lineman are our friends, and my dear Uncle Bill was a lineman. BUT, no one has explained to me how a 5000-watt generator can bring the whole grid up to 120 volts (or the high-tension lines up to thousands of volts) without turning on every light, and fridge, and toaster in town. And 5000 watts can't do that."Certainly, a 5000 watt generator is not going to light up the whole city if it backfeeds out on the electrical service. However, it only has to backfeed as far as the lineman who's up on the pole outside your house to be a big problem.
David , we all had this talk last time, from the pictures I saw the grid is laying all over the place and
the generator doesn't have to energize the whole grid................just one wire "
Good point about the all the wires down. That does increase the risk in that it decreases the load on an inproperly connected generator.
What are the chances they'll use this as an opportunity to underground the wires, avoid much of this in the future (and improve the view)? I'm thinking pretty low since they'll have so much on their hands.
The Oakland Hills fire (1991) area sure looked better afterwards for undergrounding the phone/cable/power. But that was only 2300 homes.David Thomas Overlooking Cook Inlet in Kenai, Alaska
underground ........is just a different headache"
"underground ........is just a different headache"
Especially below sea level!
But for 130 MPH winds, it is more resistent.David Thomas Overlooking Cook Inlet in Kenai, Alaska
transmission underground ?lets not hold our breath"
I might be mistaken, but doesn't the neutral line remain connected to the grid? The transfer switches that I have seen only disconnect the "hot" wires from the grid. The potential for harm is still there with a transfer switch, though it is greatly reduced.
Cramps,since the neutrals tie together in the xfr switch, and the service neut. is already grounded, there is not much of a problem upstream"
How could the neutral cause a problem?
It connects your neutrals and grounds to those of a few neighbors, and to the center tap of the utility transformer secondary. If your transfer switch keeps the utility hots separate from your generator, the only real effect of not interrupting the neutral is to give your active system the benefit of a few more ground rods.
To get a problem from the neutral, you have to assume a whole bunch of unlikely things, like the neutral being shorted to something hot because of somebody else's backfeed, and not well enough grounded.
It seems to me that there are two options that make sense:
1. Portable putt-putt genny, extension cords, fuggedabout the house wiring and the grid. Fridge, TV, a couple lights -- rough it until they get things fixed.
2. Big enough genny to supply the whole building, proper code compliant transfer switch.
-- J.S.
This issue has been beat to death. I assume I have made my opinion clear. Extension cords are OK with a little care. An adaptable and safe solution that can be used in other locations or a job site. Transfer switches installed by qualified personnel, grand, but expensive. Backfeeding a panel bad, dangerous and foolish. A few thoughts to add to the mix: I chose a hybrid system for a house.I have a recessed male receptacle with an in-use cover. This is wired to a simple 20A circuit wired to dedicated receptacles, completely segregated from the normal wiring, which are located where most needed within the house. I chose grey for the generator circuit receptacles to differentiate them from the normal POCO power.I have one of these dedicated receptacles in each room and doubled up in a few spots. This almost eliminates the need for extension cords within the house. The generator is connected to the male receptacle, prongs stick out to make the connections in the female cord cap coming from the genset, by a short cord. This also eliminates the need to snake cords through windows or doors. A safety issue, cords can be damaged and short out, and it lets rain and/or bugs in.Generator sized to run only minimal loads with some rotation. Freezers and refrigerators can be run an hour or two twice a day and go virtually forever this way. A tiny AC unit keeping a single room cool substituting for cooling the whole house or even just a fan if everyone id healthy. A single light and radio or perhaps a small portable TV standing in for the larger units. A small microwave, a coffee pot and single burner hot plate used one at a time can get a family through the hard times. My small generator, a small 3kva unit, will even run a small 120v water heater and the well. Got to shower by candlelight but it is quite romantic. And everyone gets clean. How many folks in Katrina's wake would kill, only figuratively of course, for a hot shower.Last I ran it I calculated it used a little less than 1/3 of a gallon every hour or so. Supposed to run 12 hours on 3 gallons, 1/4 gallon per hour, but I think this is overly optimistic. Low consumption stretches the supply. I try to keep 20 gallons on hand but have storage for 30 gallons. 60 and 90 hours run time respectively. A little more than a week or ten days at eight hours a day.I find it interesting when people buy larger, sometimes 25kva units, and then figure out how much gas they are going to need. What happens to this gasoline after six months of storage, possibly a year with a good stabilizer. Rotation of this stored fuel is seldom contemplated. It can be quite an involved process when dealing with even just a few hundred gallons. With a supply in five gallon containers it is simple to dump one into the trucks tank and refill it on the way home from a job. Old stuff gets used and replaced with new.
The big backup generators here are diesel. We had one start up automatically during an internal power failure once. Worked fine, but the cloud of black smoke it blew starting up led to rumors of an explosion. ;-)
-- J.S.
propane or ng as fuel
bobl Volo, non valeo
Baloney detecter
Unfortunately, you hit the conditions right on the money. The following got a lot of press when it happened, and I heard even more, as I was working for CL&P at the time.
Hurricane Gloria, 1985, state of CT. Lineman went to repair a downed line, power locked out and tagged upstream, sole load downstream on the downed line was a single house back off in the woods. Lineman picked up the line, and was instantly electrocuted. House had a generator running, and was backfeeding the length of downed line.
Not a very likely scenario, but the lineman was killed, nevertheless. A whole lot of things could have prevented it, including the lineman checking the line before picking it up. A lot was changed after that, including increased safety procedures and double-checking buddy systems, as well as minimizing overtime in emergency situations.
It will happen again, though, unfortunately, you can bet on it.
I have a Gentran unit that isolates 7 separate loads - 3 220v loads and 4 120v - powered by an 8kv fully loaded generator. Got it after a big winter stormed knocked out power for a day or two 15 years ago. It's only been used for a couple hours once or twice a year since. Best insurance against a power outage I ever bought.
"I am the master of my fate, I am the captain of my soul." Invictus, by Henley.
I would just add my utter condemnation to the neighbor's back feed scheme.
You state, "What your neighbor did was safe IF done correctly and carefully." This is not true. It is not safe since there is no guarantee that the main breaker will be turned off. This is the type of accident which is known to happen and can be prevented. Thus it is unexcuseable. Think manslaughter or willful, reckless endangerment. Report the neighbor to the utility.
~Peter J. Michael
Thanks to all for your responses. I'll either get the right switch or stay with the extension cords.
transfer switches that'd work with the smaller/portable generators
simplest is to install 3 way light switches with the center to the load receptacle (freezer, fridge, furnace) one traveller to the CB panel, the other to a breaker that plugs into the generator. Poor man's code compliant transfer switches.
Hey Guys,
A circuit breaker is either OPEN or SHUT. Telling your buddy to "shut off the breaker" might get you a hair raising response.
You may "shut off a light" or "turn off a motor", but you either OPEN or SHUT a breaker.
Chris
Actually, it is OPEN or CLOSE the breaker or switch. This is opposite from plumbing. In plumbing, if you OPEN a valve, the water flows and in electricity, if you OPEN a switch, the juice stops.
And vice versa.
SHUT is something you do to a door or a curtain. Or, in tin knocker lingo, you may SHUT a damper.
Hope this sets the terminology straight.
~Peter
Well that certainly sounds open and shut to me. LOL" If I were a carpenter"
bill,
Hope you weathered the storm w/o too much damage.
I'll second those posts that say what your neighbor did is neither safe nor up to Code.
Not safe, because as others have mentioned, if the person deploying the generator forgets to shut off the main breaker, the power will be sent back into the utility secondary grid, and thence into the step down transformer, which will then become a step up transformer. It's possible that under certain, not unlikely circumstances, the 120 volts could turn into a few thousand volts on the primary distribution lines.
David T. is right on one count, that energy might not travel far. But then, it doesn't have to if there's a guy up a nearby pole working and he's made a simple mistake, or a neighbor is moving a down line, thinking that the power is out (and won't be coming on for a long time). I don't think either one of them deserves to die just because someone is too cheap to not install a proper transfer switch, or suffer the inconvenience of running extension cords for temp power.
Either the 120 volts or the high voltage could injure or kill a lineman, even if he's taken all the precautions. Stuff happens up a pole, in bad weather, when you're tired. A gaff cuts out, a wire breaks or is whipped around by the wind, and there's accidental contact between the lineman and the energized wire. In a power outage, the power companies work the line crews 18 hours a day, seven days a week, in the dark, in the storm. So sometimes a dead-tired lineman makes a mistake, and having a home generator feeding power back into the power lines just makes the odds of injury or death that much worse for the guy up the pole.
If you don't care to be concerned about the linemen, how about the neighbors or someone just walking down the street? Downed lines, no power in the area, someone might think the wires on the ground are dead, or that their house power is out, do something stupid, and be shocked or electrocuted. Think that's just Darwinian selection? How about the poor schmoe who inadvertantly touches a down line, that your neighbor has inadvertently energized?
That doesn't even cover all the possibilities for problems, but you get the idea.
I just don't see why people jerry-rig these backup generator hookups. It's just too easy to mess up and forget about the main breaker, and send power back into the grid. If someone can't afford to do it correctly, they should use the low-tech approach and get along with extension cords.
Cliff
the day after Katrina at a press conference in MS I think, ####rep from the ELEC utility, stood on the podium and stated that the only safe way to connect anything to a gen was through extension cords,
you can assume that he was referring to generator usage during this current calamity.
The reason for this setup is to absolutely guarantee that there is no chance of a backfeed into the mess that is left of their distribution grid which could injure or kill anyone
(including lineman) contacting those downed lines
When life returns to normal down there please install a transfer switch , or do what you did this time and forget about the "rube "
setup your neighbor uses !!!!
I hope all is well for you
I would be suprised if it passes code. Code would require a dedicated breaker panel between the mains.
Others should consider using propane as their fuel choice. Generators are seldom used and those that are powered by gasoline suffer from volatality loss [dead gas] after a few week of above ground temp. storage.
best of luck