120V Lamps on 240V?

My neighbor the (um) electrician tried backfeeding his house through a 240V receptacle in the garage. The generator is a real old-timer: open frame with cotton cloth insulated wire in the windings. The three-wire output from the alternator is terminated at a three-position terminal board, unmarked and no terminal is grounded to the frame.

Neighbor *guessed* how to connect this to the house ... never bothered to check voltages with a multimeter. Immediately after starting up the generator, he observed that the lights were "real bright". So he shut down and ran a wire from the generator frame to a piece of conduit driven into the ground. Alas, the second startup was like the first and quickly aborted and declared an unsolvable mystery.

Neighbor went into the house, noticed smell of burning insulation everywhere. He filed a claim with his insurance company for damage due to an electrical surge: microwave oven, VCR, two televisions, cordless phone, clock radio, control transformer in furnace, etc. The refrigerator and two freezers were not damaged.

My guess is that he misconnected the genny, putting 240 on one side of the service and zero on the other. The three coldboxes were lucky to be on the zero volt side. But would a light bulb operated at 200% rated voltage just become "real bright" and survive a couple of brief tests or become an instant flashbulb?

Roby

ps: This guy really is an electrician ... or at least has been selling his time as such for about 20 years. Seldom gets additional work from old customers though.

Reply to
Roby
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He works cheap (which is why he gets work at all); midwestern US. A sample: you can save a wire by just running hot and neutral to a grounding receptacle ... and then connect a jumper between the neutral and ground terminals at the receptacle. It's amazing (scary, really) that this sort of thing goes on.

Roby

Reply to
Roby

Ooops ... you're right about the volts! I don't know what it really is/was. He put it back in storage; will likely try again someday. I wish I didn't live right next door!

Reply to
Roby

through a 240V

old-timer: open frame

three-wire output

terminal board,

never bothered to

starting up the

So he shut down

conduit driven into

quickly

He is a WINNER.... Darwin would be proud. You should send this in to the awards committee.

insulation

damage due to

cordless phone,

refrigerator and two

whatta guy.

one side of the

lucky to be on the

become an

you got it

been selling his

work from old

Whats his billing rate and what region of the country... enquiring minds want to now.

Phil Scott

Reply to
Phil Scott

Well that neighbor, if really an electrician, is a real dim bulb for a) not marking the generator leads before connecting it, and b) not figuring out what happened the first time he fired it up.

If he had swapped the neutral and a hot, half the devices would get 240 volts and the other half would get 120 volts, not zero. (assuming it is a 120-0-120V generator. Is it? Might be anything if that old)

I've heard two things: The lifetime of an incandescent bulb is inversely proportional to the 12th power of the applied voltage, and at one time photographers onced used 60 volt railroad bulbs at 120V for bright white light output, even though they didn't last long at all.

If the first is true, the incandescent bulbs, assuming a rated lifetime of 1000 hours, would last about 1/4000 of that, or about 15 minutes if brand new. Assuming, of course, the 12th power relationship, if true, works at the extreme of doubled voltage.

I don't really know if 'railroad' bulbs exist(ed), or if they were designed for 60 volts, or if photographers really did use them.

Reply to
Michael Moroney

I used to have some old 60 V. bulbs that were originally from an old AT&T Telephone test board at one of their abandoned Long Lines Microwave Facilities. These were standard Edsion based incandescent bulbs that came in different colors (yellow and red). Not sure exactly what they were used for but they did exist.

Beachcomber

Reply to
Beachcomber

|>My guess is that he misconnected the genny, putting 240 on one side of the |>service and zero on the other. | | If he had swapped the neutral and a hot, half the devices would get 240 | volts and the other half would get 120 volts, not zero. (assuming it | is a 120-0-120V generator. Is it? Might be anything if that old)

And 120 volts to the 240 volt loads.

If he picked up some surplus military generator, it could be a 416Y/240 model. It might be reconfigurable to 208Y/120.

| If the first is true, the incandescent bulbs, assuming a rated lifetime | of 1000 hours, would last about 1/4000 of that, or about 15 minutes if | brand new. Assuming, of course, the 12th power relationship, if true, | works at the extreme of doubled voltage.

I did that many years ago to a 60 watt bulb. It lasted about 20 minutes. Another bulb lasted about 20 seconds. The former could have been one of those "130 volt" bulbs intended for longer laster in hard to reach places. The latter could have been a cheapie.

Oh, and the 240 volts was gotten from one of those travel transformers in reverse. It may have been sligtly less than 240 volts.

Reply to
phil-news-nospam

alas, unless he actually dies he just doesn't qualify for a Darwin. killin' someone else don't count.

Reply to
TimPerry

house

bright".

first and

send

Darwin. killin'

awww shit. I thought we had a winner there.

Reply to
Phil Scott

formatting link
he might qualify for an honorable mention:

The stupidity displayed by the participants in the following tales stops short of the ultimate sacrifice, but we salute their spirit and innovation

Reply to
TimPerry

Probably much less. Those are usually rated 50 watts. The over driven bulb draws more current and pulls down the voltage.

At the melting point of tungsten, those mathematical relationships are no longer valid! John

Reply to
JohnR

|> I did that many years ago to a 60 watt bulb. It lasted about 20 minutes. |> Another bulb lasted about 20 seconds. The former could have been one of |> those "130 volt" bulbs intended for longer laster in hard to reach places. |> The latter could have been a cheapie. |>

|> Oh, and the 240 volts was gotten from one of those travel transformers |> in reverse. It may have been sligtly less than 240 volts. | | Probably much less. Those are usually rated 50 watts. The over driven bulb | draws more current and pulls down the voltage.

It was rated 600 watts.

Reply to
phil-news-nospam

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