I'm sure it has happened, but it is not a rampant problem. Linemen are probably more likely to get robbed by a crackhead than electrocuted from a backfeed. I saw a POCO do a demo about back feeding a 25 kVA transformer from a 5000 watt generator. The first try, the in-rush tripped the breaker on the generator. The second try killed the engine completely. They had to fiddle around with the governor to over-rev the engine while throwing the transformer on line just to get going. Given that and the fact that there will be many neighboring services being energized at the same time, I bet it happens very rarely.
Power out and generator hookup.
- Thread starter qcroanoke
- Start date
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
Once is too often.
Of course. I'm not advocating that anyone do it without an interlock of some sort. I'm simply stating that these breathless claims of linemen dying left and right are nonsense.
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
Unfortunately not as rarely as you may think. And it endangers us, too.
Let's see some numbers. How many linemen a year are injured by back feeding?
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
Why? What's your acceptable number?
You're making a claim. I'm asking for substantiated figures. There is no number of persons killed by electricity that's acceptable, except maybe executions.
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
I have no idea, beyond it being more than zero. The point is that it is easily preventable.
The number is not important enough for me to research it. You're welcome to if you wish.
Oh, gee thanks. I don't think it is preventable. There are means to prevent it, but stupid people will always do stupid things. Until we outlaw generators and the sale of screwdrivers to the general public and then hire an army of police to enforce it, dumbassery will always exist .
ggunn
PE (Electrical), NABCEP certified
- Location
- Austin, TX, USA
- Occupation
- Consulting Electrical Engineer - Photovoltaic Systems
I'm pretty sure that he meant that is preventable by following the rules. If one does not follow the rules, then of course all bets are off.
qcroanoke
Sometimes I don't know if I'm the boxer or the bag
- Location
- Roanoke, VA.
- Occupation
- Sorta retired........
This is where Google and hacks collide.
- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
One anecdotal report, not clear from the report what the size of the generator was, but possibly not residential?
www.cdc.gov
FACE Program: In-house Report 90-05 | NIOSH | CDC
A construction crew consisting of a supervisor, three class A linemen (including the victim), a first class lineman, a groundman, and two truck drivers were assigned the task of correcting a malfunction in a de-energized three-phase powerline.
www.cdc.gov
Birken Vogt
Senior Member
- Location
- Grass Valley, Ca
If you can't see the big orange grounding jumpers with your own eyes, you don't touch the wires.
electrofelon
Senior Member
- Location
- Cherry Valley NY, Seattle, WA
I agree. These stores of "a downed line being flagged/marked/ tested as dead" is nonsense. It doesn't work that way when you working with medium voltage.
Seven-Delta-FortyOne
Goin’ Down In Flames........
- Location
- Humboldt
- Occupation
- EC and GC
When I was a Union Apprentice, we re-wired a small company town, owned by the pulp mill, which produced the power for the town.
We would put the jumpers on the line side of what we weee working on, obviously. I wonder if linemen these days ground both sides of the work area? I know I would be inclined to, if I did high line work.
kwired
Electron manager
- Location
- NE Nebraska
One those rules is if it isn't grounded it isn't dead, particularly the process with medium and high voltage. With low voltage secondaries they maybe don't connect bonding jumpers all that often, but generally there is more isolation of such lines as well.
If they are fixing up a downed service drop, they usually have meter pulled. In ordinary situations that keeps them from making connection with an active load present. Works both ways when it comes to potential back feed from a generator.
hillbilly1
Senior Member
- Location
- North Georgia mountains
- Occupation
- Owner/electrical contractor
Most around here are 5 or 10 kva. Very rare for the poco to put anything larger for residential.
That's true, but there are tons of other transformers in the utility circuit. Each of those will have refrigerators and pumps and A/C units all trying to start at the same time.