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Re: Found in a hotel in Nashville, TN #105559 05/03/05 08:14 AM
Joined: Feb 2005
Posts: 693
L
Larry Fine Offline
Member
Either that, or someone else will run the generator without knowing the "proper" improper procedure. The rules are there to protect the world from the ignorant.

I've been on more than one job where another electrician set up the connect with a double-plugged cord. I told the homeowner about the error, but two years later, it was still the same.


Larry Fine
Fine Electric Co.
fineelectricco.com
2017 / 2014 NEC & Related Books and Study Guides
Re: Found in a hotel in Nashville, TN #105560 05/03/05 09:03 AM
Joined: Dec 2004
Posts: 329
I
IanR Offline
Member
Just the other day, when I came home from work and looked in the garage, I saw one of these monstrosities laying there. It was a 6-30 dryer cord attched a length of 14-3 with a 5-15 plug. Needless to say I was taken aback. "What the heck is this and how did it get into my garage?!" After dimantling this death device inquired about it to my family members. Turns out a well meaning, yet un informed, neighbor dropped it off so I can connect my generator during the next hurricane. I am going to have a talk with him about this widowmaker the next time I see him as I am sure he has one these and intends to use it.

Re: Found in a hotel in Nashville, TN #105561 06/19/05 12:40 AM
Joined: May 2004
Posts: 11
J
JimMichaels Offline
Member
These "Suicide" cords are obviously a real danger to anyone plugging them into a live outlet (or two...).

However I am dubious of stories about linemen and home generators.

If one of these were used with a generator to back feed a house during a power outage, the generator would attempt to power the entire grid downstream of the utility fault through a 5-15 outlet and it's 20amp (or 15amp)Circuit breaker (or fuse). Assuming the utility fault is an open, 20amps or so is not going to power dozens if not hundreds of dark houses. Even with a huge generator and a 14-50 (or 10-50) range plug Suicide cord the load of an entire neighborhood of houses is going to trip a breaker or stall the generator.

If the utility fault is local enough to only affect one or two houses then the lineman would not be expecting dead lines. Also he should hear the generator at such close range.

If a lineman did encounter the power from a back fed generator it would certainly not have enough power behind it to cause big sparks or other thermal effects.

A much more likely cause of Lineman injury/death would be inductive coupling to other live power lines or most likely the unanticipated re-energization of the segment he is working on.

In any case ALL lineman injuries/deaths from these events are avoidable by following mandated grounding procedures!

I would like to hear any accounts of back fed home generators that caused injury/death or even a tingle to a lineman. I assume any investigators would confirm that the generator was actually the source of the current in question.

Sample procedure; measure voltage at site of accident, turn off generator, re measure, restart generator, re measure to confirm cause and effect.

Re: Found in a hotel in Nashville, TN #105562 06/19/05 02:50 AM
Joined: Jul 2004
Posts: 625
S
SolarPowered Offline
Member
Jim, there are scenarios that can and have caused the deaths of utility linemen.

One scenario is where the distribution-voltage line is interrupted between the transformer serving the house with the generator, and the rest of the grid. The generator back-feeds the local transformer, producing distribution voltage (typically 7,200 to 22,000 volts) on the supposedly "dead" lines. The amount of power that can be delivered by the generator is more than sufficient to kill someone working on the lines.

Re: Found in a hotel in Nashville, TN #105563 06/19/05 08:01 AM
Joined: Jul 2004
Posts: 145
C
chipmunk Offline
Member
Quote
The amount of power that can be delivered by the generator is more than sufficient to kill someone working on the lines.


Agreed there, add to that the probability that the cause of the outage may be a storm, and you have a soaking wet lineman up a pole, probably at 3 am on a sunday, who is really *not* expecting 7200 volts from a transformer that's disconnected from the grid. Given the howling winds likely, he/she is also probably not going to hear the generator. Agreed, safety is the lineman's responsibility, but there's no excuse for using something suicidally and homicidally dangerous when transfer switches are very readily available.

Re: Found in a hotel in Nashville, TN #105564 06/19/05 11:53 AM
Joined: Jan 2005
Posts: 5,316
renosteinke Offline
Cat Servant
Member
You know, this brings up an area in which I am both ignorant and leery.....backfeeding the PoCo lines.

Most places have "net metering", where the homeowner can generate their own power, and feed any excess back to the PoCo.

The "Alternative Energy" press quite freely asserts that the idea that this might endanger a lineman is simply a canard put out by the evil PoCo, that "their methods prevent this." How? I wonder?

A lovely as self-reliance and energy independence may be, this attitude, and the cavalier attitude of some in the alternative energy field (and the ignorance of the rest) toward the NEC causes me concern.

Add to this the fact that all of my few encounters with home generation have been to correct major goofs made by the installer, and I am not reassured!

Re: Found in a hotel in Nashville, TN #105565 06/19/05 08:35 PM
Joined: Sep 2001
Posts: 806
N
NJwirenut Offline
Member
Yes, the casual attitude about backfeeds and other safety issues among some alternative energy folks is pretty scary. The causes seem to run the gamut from sheer ignorance (the majority) to outright hostility toward the "evil gridmongers" and their employees. [Linked Image]

Inverters intended for use in net metering arrangements are supposed to incorporate circuitry that prevents backfeed to the grid in the absence of grid power. In the event of a utility dropout, the inverter goes into a standalone mode until grid power is restored. Even then, most power companies require a visible break disconnect switch installed on the outside of the building, where it is accessible to POCO personnel.

SOME alternative energy publications TRY to get it right. The "Code Corner" column in HomePower magazine is a great attempt at explaining the NEC requirements (and the reasoning behind them) to the alt-energy DIYer. Now if they would just dump the "Solar Guerilla" pieces where they show how to install systems WITHOUT inspections or PoCo approval, they would be doing a REAL service to everybody...

Re: Found in a hotel in Nashville, TN #105566 06/27/05 09:11 PM
Joined: May 2004
Posts: 11
J
JimMichaels Offline
Member
In SolarPowered's & Chipmunk's scenario the house would have to be the only load on the transformer.

Even if the generator could not be heard the fact that the house had lights would be a big clue that a generator exists.

Anyone who grabs a wet 7200V line because they "think" it is dead is Darwin award material.

Except in very rural areas the transformer could easily be backfed by another transformer (this is more common than generators).

"There are scenarios that can and have caused the deaths of utility linemen."
My request was info regarding any documented cases, not just the fact that it could happen under the right combination of errors.

Statements that it did happen somewhere sometime with no further information are barely hearsay, let alone evidence.

The cord isn't the danger to a lineman it is the implied lack of an interlock between the genrator feed and the utility feed.

Example, an electrician connects a temporary generator during a power outage using a cord with male end connected to a breaker that will be removed when generator is disconnected.
If the main breaker is lockedout (&tagged)
how is this less safe to the lineman than a transfer switch?

What NEC rules have been violated?

Re: Found in a hotel in Nashville, TN #105567 06/27/05 09:59 PM
Joined: Nov 2002
Posts: 788
W
wa2ise Offline
Member
Quote
Example, an electrician connects a temporary generator during a power outage using a cord with male end connected to a breaker that will be removed when generator is disconnected.
If the main breaker is lockedout (&tagged)
how is this less safe to the lineman than a transfer switch?


The problem is that someone backfeeding a generator into the house wiring may forget to turn off the main breaker. The transfer switch is designed to make sure the user disconnects the house wiring from the POCO and connect it to the generator. The transfer switch requires only one action, where the "backfeed the generator and shut off the main breaker" requires two separate actions. Which might not get done. It's a bit like the rules at the shooting range: "put the safety on, take the magazine out, keep the gun pointed to the floor, and never aim at anyone". Redundant, but with something that can be lethal, you need redundancy.

Re: Found in a hotel in Nashville, TN #105568 06/30/05 03:00 AM
Joined: May 2004
Posts: 11
J
JimMichaels Offline
Member
I agree this not for the untrained.

We all do many thing everyday that are potentially lethal to us and others.

Locking out the main before connecting the generator is a very simple proceedure compared to driving a car or shooting a gun at the range.

A transfer switch takes it to idiot proof, similar to only being able to fire the gun when it is actually pointed at the target.

I am NOT advocating the backfeeding of utility lines. I am merely trying to better understand the mechanisms of danger and assign some relevance to them.

Closing your eyes and firing a gun is dangerous. But if you are alone in the woods the danger is different than on a crowded sidewalk downtown.

The generator danger occurs when ALL of the following occur at the same time:
1. Power line breaks between single house and grid.
2. Generator operator fails to isolate main.
3. Lineman does not measure line.
4. Lineman fails to install ground.
5. Lineman touches line on transformer side of break knowing that he is violating his work rules regarding #3 & #4.

#2 is prevented by a properly installed transfer switch.

If the Electrician is incompetent to lockout the main, is he competent to install the transfer switch?

A tranfer switch is the best solution.
What level of operator competency makes other solutions viable?

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