Generator Wiring

Easy and effective and illegal here. The safety issue is that it is possible to feed power back to the transformer and energize the high tension line while someone is working on it. Real transfer switches won't allow this.

Practically speaking it is unlikely that his generator could pick up all the loads connected to his distribution system without tripping out, but there's always the chance that some lineman could be working on just a short section of line and didn't ground it before starting, or the HT line could be laying on the ground right outside his house.

Simple effective and ill-eagle here in the SW US as well. If caught here he will serve a minimum of 2 years in jail. I have been the lineman who got zinged from just such a installation. I called the police had the offender arrested, confiscated the generator. Then I chopped the service conductors from his house. Took several months of court proceedings before the reconnection of the residence. I refused and my supervisor did not even ask me the second time.

The NEC is clear there must be a disconnecting means between the sources physically preventing both mains being closed at the same time. Your cord and cap method do not meet the intent of the code no physical method of protection. Have your buddy call the serving utility and get the regs from them. Follow them to the letter and have the utility inspect it when he is finished with the changes. My fellow linemen will thank you.

Unsafe and illegal, for reasons noted by earlier posters. Another point: the cord between the generator and the receptacle is male at both ends - that is unsafe.

In addition, when he closes the 40 A breaker, he is suddenly loading the generator with all of the house loads that are on at the time he flips the breaker. Not a good procedure - there are gentler and safer ways to treat the generator.

Let me get this straight. He is using a 40A DPDT supply transfer switch? Isn't this unusually low for the main electrical service to a home?

If he is merely disconnecting his main breaker and (unsafely/recklessly) backfeeding his service panel, why does he need a DPDT switch on the generator, and what is the reason that it is double throw?

I'm confused, but that's nothing new after reading so many posts to this newsgroup...

Harry C.

Can you explain the circumstances of the mishap? It seems to me that unless the line problem was directly on the miscreant's service that his genny would stall immediately as he tries to backfeed the entire grid; but I have never heard an authoritative opinion on this.

Glad you are alright.

I give up, what is a DPDT breaker. Well, I know it is double pole, double throw; but I have never heard of a double throw breaker.

miscreant's

Homeowner had connected a 10 kw gen set to his service and was back feeding his service. The line reclosers had opened way down stream and most of the fuses locally had blown. We were out replacing fuses some 2 miles away starting at the recloser and working to the end. I went to work in a bucket truck, gloves etc. Another crew shorted the lines together farther away. The local fuses I was installing immediately blew. The resulting shower of particles was disturbing. That is when we went looking for the generator. We knew the lines were dead, they had been locked out ahead of us so we could work faster. Since I was just replacing fuses I did not ground the lines in each location. Just pull the fuse and replace. Except there should have been no voltage or current.

That's not the biggest risk. The BIG risk (potential) is the male/male "extension cord" which is an accident waiting to happen.

I am curious where one gets a DPDT breaker.

I have seen panels that accomplish this via a mechanical interlock. Is that how this was done?

EMWTK

Well the male-male is a winner . . . I just figured that was one for Darwin and God to sort out.

Probably a Double Pole breaker which services both sides of the mains a 240 volt breaker. At least that's what I took it to mean.

Two things that I see. You have the exposed blades of the range type receptacle that can be energized. I assume they are on the 40A breaker in the panel. If the breaker is turned on with the panel energized someone could get hurt.

The other is that there is no interlock to prevent tying the generator to the incoming line. You need to have your generator connect in such a manner that just forgetting does not lead to backfeeding the line.

I know, I know, your friend would never make these mistakes. People rarely make misteaks (ha ha). Plenty of dead line man would tell you different. Or maybe their families would. You wouldn't want to meet their co-workers (believe me).

We had a major ice storm last spring and I know two people who forgot to disconnect their generators before throwing their main back on. It cost one his generator, I'm sad to say it didn't cost the other anything.

I may sound harsh, but I have lineman as friends and there is a lot of risk in their jobs, but they don't want to die because someone is too lazy to do a job right.

Interestingly enough, I can remember a big push Down Here (Australia) a few years back for nearly all line maintenance to be done live - to prevent situations like you have just described.

I have been up a pole doing live work simulations (11kV service), with the rubber gauntlets and all the rest of it, and it felt *a lot* more comfortable knowing the lines were live and having the equipment, procedures and training to handle it, rather than assuming they were dead and finding out the hard way.. It's less disruption to consumers as well.

Since these procedures were introduced, IIRC there have been fewer "accidents" and the lineys job is not too bad. As pointed out elsewhere though, on the consumer side of the pole it's a different story - electrified roofs, rainwater tanks, trees, gas mains(!)...

Cameron:-)

Most work is done live here as a matter of course. Did a short stint myself working part time for a line construction company. I think there are situations where the power is off and it just isn't possible to insulate well enough to protect the line man. Ice storms and hurricanes - where the lineman is working in wet conditions trying to bring the power up.

The line is supposed to be dead, and the lineman is supposed to ground it for his safety. Sometimes the pole ground wire isn't a good ground or someone has stolen a few feet of copper off the pole, or the lineman is forgetful (almost never). Most accidents of this type require a few errors before a fatality is realized or someone is hurt.

I know we didn't work in the rain, doing ordinary construction and maintenance. The buckets had ankle deep water (no drains), water drips into the gloves, and down the "shotgun" poles and truck booms, on the mats, etc. A lot of work in storms is done with no truck, just climbing spurs on the grounded pole.

I'm with you ... a male to male connector is a death wish! Take care, Ross

They don't call them *SUICIDE* cords for nothing!!!

daestrom

In article , snipped-for-privacy@primecs.com says... | I have a friend who has a generator wired to his main panel as such: | | 40A DPDT breaker to range style, 4 prong plug; power cord | w/corresponding 4 prong male plug on one end, and 4 prong plug to | connect to generator on the other. During a recent power outage, he | threw the main breaker (off), started the generator, plugged the range | cord into the 40A breaker plug, then after the generator was warm, | plugged the other end into the 40A/240V connection on his generator | and closed (on) the 40A breaker that this all fed, in the circuit | breaker, effectively backfeeding the breaker panel. | |

I would think this procedure will be highly illegal in most countries. The possibilities are that there is an awfully good chance that you will try to back feed out to the network, when someone could well be working on that network and a personal danger whilst making the connections of either end becoming live.

The only way to safely accomplish this would be with a designed for the job interlocked switch which ONLY allows feed from the generator OR the network.

It is only dangerous if you plug it into the generator first. Even then it is not particularly dangerous unless the generator is grounded and has a bonded neutral; which would probably never occur where a suicide cord is used.

There is a debate over whether generators should be grounded. If they are not, the grounding conductor is useless; but since they are not grounded, it is very difficult to get any kind of shock off them (except obviously hot-neutral), so it doesn't much matter.

What would have happened had that particular fuse not blown previously? Would his gen stall when he plugged it in, or would all have been well until the line shorted?

Completely untrue. Whether you plug it in at the generator first, or at the house first, it is dangerous. If you plug it in at the house and walk out to the generator, while you are walking house power could come back on, energizing the male plug at the generator end. If you plug it in at the generator end first, the male plug at the house end becomes energized if the generator is on.

It has nothing to do with whether the generator is grounded or not.

The problem with a suicide cord is the exposed or exposable energized metal prongs of plug, with no positive mechanical means to prevent human error. If the "suicide cord" is plugged into a "live" source at EITHER end, there is hot-neutral-hot available at the other end, regardless of whether the generator is grounded or not.

If you plug it into the (ungrounded/unbonded) generator first, you can touch the exposed hot plug and nothing will happen. The current has no place to go; if you try it with a generator that has a GFCI, it will not even trip. If you touch the hot and neutral, you will certainly regret it, but it should not (under normal conditions, got to cover my ass) be particularly dangerous. (No, I haven't tried either one, but I have read reports of those who have.)

Certainly it is dangerous to plug it into the line outlet first if you haven't opened the breakers; but that is like saying that it is dangerous to backup a car because there could be someone standing in back of you. They are both "possible", but equally hard to do wrong.

I am not advocating use of suicide-cords. They are dangerous because people use them every few years and get confused about what to do, or never knew in the first place. But they are not anymore inherently dangerous than a garbage disposal or a table saw; probably safer.