Generator and electricity flow

[Diamondpilot]

So just to be clear, NEC is ok with the interlock breaker system?

Yes but check with your electric provider and make sure they are ok with it also.

Chris

 

[grsthegreat]

interlock is just fine by nec...as long as its a UL rated system.

 

[bcp]

A current generator thread lead me to this old one where I saw a generator backfeed comment.

I challenge anyone tyo publish a single electrocution event of a linesman attributed to a home generator.

A quick search found a couple of backfeed incidents, one a home generator, the other industrial, and the sources aren't just "someone said it happened."

======================

From:
Pike Electric, Inc., Docket No. 01-0166

After Green left, Adams went up in an insulated lift to repair the damaged lines. Three of the lines (the neutral, the road phase, and the field phase) were broken. The fourth line (the central line) was sagging but intact (Tr. 61). Although Adams could have repaired the sagging central line without splicing it, he chose to cut the line. The line on which Adam was working was connected by a secondary line to a house at the end of Jackson Street (referred to at the hearing as “a doctor’s house”). The homeowner had connected a portable generator to the house’s circuitry which caused electrical energy to backfeed to the line Adams was splicing, energizing it. Adams was electrocuted when he cut the line...
===============

From:
http://www.ok.gov/health2/documents/PrevAtWork_Work_Electrocution_Deaths.pdf

A young adult electrician was working 20 feet off the ground on an
electrical pole wire that was thought to be
uncharged. The worker was electrocuted when an oil
well generator back fed and charged the line. His
coworker had to drive an ATV five miles to get help. The
electrician died at the scene.

 

[Gale Hawkins]

A current generator thread lead me to this old one where I saw a generator backfeed comment.



A quick search found a couple of backfeed incidents, one a home generator, the other industrial, and the sources aren't just "someone said it happened."

======================

From:
Pike Electric, Inc., Docket No. 01-0166

After Green left, Adams went up in an insulated lift to repair the damaged lines. Three of the lines (the neutral, the road phase, and the field phase) were broken. The fourth line (the central line) was sagging but intact (Tr. 61). Although Adams could have repaired the sagging central line without splicing it, he chose to cut the line. The line on which Adam was working was connected by a secondary line to a house at the end of Jackson Street (referred to at the hearing as 殿 doctor痴 house?. The homeowner had connected a portable generator to the house痴 circuitry which caused electrical energy to backfeed to the line Adams was splicing, energizing it. Adams was electrocuted when he cut the line...
===============

From:
http://www.ok.gov/health2/documents/PrevAtWork_Work_Electrocution_Deaths.pdf

A young adult electrician was working 20 feet off the ground on an
electrical pole wire that was thought to be
uncharged. The worker was electrocuted when an oil
well generator back fed and charged the line. His
coworker had to drive an ATV five miles to get help. The
electrician died at the scene.

These are sad cases you shared but as you read in the first chase this death was possible because of failures of the power company and staff. Assuming is often dangerous for the workers and code assumes there is going to be an unknown potential of a wire being HOT. The home owner was wrong for sure but that is to be expected by the professionals.

"Occupational Safety and Health Administration (OSHA) compliance officer Dale Schneider investigated Adams痴 death on July 13, 2005. As a result of his investigation, the Secretary issued two citations to Pike on January 6, 2006.
Citation no. 1 alleges a serious violation of 29 C.F.R ｧ 1910.269(a)(3) for failing to determine existing conditions related to the safety of the work to be performed before work on or near the power lines was started. The Secretary proposed a penalty of $ 7,000.00 for this item.
Item 1a of citation no. 2 alleges a willful violation of 29 C. F. R. ｧ 1910.269(m)(3)(ii) for failing to open all switches, disconnectors, jumpers, tags and other means through which known sources of electric energy may be supplied to the particular lines and equipment. Item 1b of citation no. 2 alleges a willful violation of 29 C. F. R. ｧ 1910.269(3) for failing to ensure temporary protective grounds were placed at such locations and arranged in such a manner as to prevent each employee from being exposed to hazardous differences in electrical potential. The Secretary proposed a grouped penalty of $ 70,000.00, for items 1a and 1b.
A hearing was held in this matter on July 6 and 7, and August 15, 2006, in Atlanta, Georgia. Pike stipulated jurisdiction and coverage (Tr. 4). The parties have filed post-hearing briefs.
Pike denies it violated the cited standards. It also asserts the affirmative defense of unpreventable employee misconduct on the part of Adams with regard to items 1a and 1b of citation no. 2.
For the reasons discussed below, item 1 of citation no. 1 and item 1a of citation no. 2 are affirmed as serious, and penalties of $ 5,000.00 and $ 7,000.00, respectively, are assessed. Item 1b of citation no. 2 is vacated."

 

[dave1949]

"The home [generator] owner was wrong for sure but ..."

So, those linemen would be alive if no generator had back fed the lines. That is all that really matters when discussing the use of interlocks. The rest, procedures, professional expectations, etc., is another issue entirely that applies with or without the generator issue.

 

[aczlan]

"The home [generator] owner was wrong for sure but ..."
So, those linemen would be alive if no generator had back fed the lines. That is all that really matters when discussing the use of interlocks. The rest, procedures, professional expectations, etc., is another issue entirely that applies with or without the generator issue.

Exactly. If I can (pretty much) guarantee that my generator will not be able to backfeed the lines for the $150 (or less) that a interlock costs, I will use an interlock. Legal liability would be nothing compared to having someone's life on my conscience for the rest of my life.

If there is a major outage, the linemen will probably be working 18+ hour days. When you work that long you are far more likely to make mistakes and I dont want to make their job any more dangerous than it already is.


Aaron Z

 

[dave1949]

Exactly. If I can (pretty much) guarantee that my generator will not be able to backfeed the lines for the $150 (or less) that a interlock costs, I will use an interlock. Legal liability would be nothing compared to having someone's life on my conscience for the rest of my life.

If there is a major outage, the linemen will probably be working 18+ hour days. When you work that long you are far more likely to make mistakes and I dont want to make their job any more dangerous than it already is.


Aaron Z

I agree. There is one way I can guarantee I and my generator will not contribute to the injury or death of a lineman, first responder, fire fighter, kids out after a storm with downed lines laying around, etc., etc.

Following an ice or wind storm, looking at a street that is a tangled mess of trees and lines, no way to know what is or could be going on electrically in that mess and connected generators only compound the problem.

I'm not sure why anyone would waste generator capacity energizing utility transformers in the first place, besides the safety issues.

 

[Gale Hawkins]

Even if one did not kill someone energizing the utility transformers when the power grid went hot from the utility one's generator could be a big ball of smoke perhaps.

 

[jejeosborne]

Even if one did not kill someone energizing the utility transformers when the power grid went hot from the utility one's generator could be a big ball of smoke perhaps.

Yes, very unlikely they would be at the same synch when they closed in. I doubt there would be any smoke though before the breaker would trip on the generator or panel. Maybe someone will go out today and make us a video and see what really happens.......

 

[Gale Hawkins]

I have not seen it but heard some expensive stories when I was in the Navy about going from ship to shore power when phase was not in sync.

Saw adding a generator shake some at KY Dam when it was not in totally in phase.