Generator Backfeeding, Suicide Cords

Hv&Lv

Senior Member
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Engineer/Technician
I think it is quite rare and really not much of a hazard. I am certainly not saying go ahead and do it improperly, but I think the risks are overblown. A generator connected in parallel with the live utility will likely just trip the breaker on the genny - I have seen it happen, it was disappointingly uneventful.

A suicide cord is certainly a shock hazard, but I think the chance of injury/fire/death from 120V to ground is quite small per instance, although if you have a few hundred thousand instances, there could be a few.

backfeeding dead utility lines could be a risk for lineman, but I think in most cases the generator would trip out from all the neighbors loads.
^^^^^^Here is the answer^^^^^
 

Hv&Lv

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Engineer/Technician
I’ve mentioned here before we have found a generator back feeding a tap behind fuses with no other transformers. Found a couple of them over the years.
I have personally thrown the fuse back in on one. The guy actually called in and wanted his generator replaced a couple of days later. Said we burnt out an IC board..

For the most part if a generator is back feeding a line that is on the ground the wires are generally twisted together creating a short. Tripped breaker. Or like electrofelon said, tripped on neighbors loads.

when we go out, rubber gloves and grounds get the guys home alive
 
I’ve mentioned here before we have found a generator back feeding a tap behind fuses with no other transformers. Found a couple of them over the years.
I have personally thrown the fuse back in on one. The guy actually called in and wanted his generator replaced a couple of days later. Said we burnt out an IC board..

For the most part if a generator is back feeding a line that is on the ground the wires are generally twisted together creating a short. Tripped breaker. Or like electrofelon said, tripped on neighbors loads.

when we go out, rubber gloves and grounds get the guys home alive
I think it was you who in another recent thread said if it's POCO vs customer equipment, POCO wins😂

So what are the protocols for working on lines that are disconnected? To be extra sure there isn't a generator backfeed somewhere, are the lines still assumed live, and/or shorted/grounded?
 

rnatalie

Senior Member
Location
Catawba, NC
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Retired Electrical Engineer
Not sure why it would affect solar. If there's no power on the grid, it makes no sense to backfeed power solar or genset provided.
In fact, the reverse metering really requires power there now in order to get the backfeed to work. It wants to lead the phase.
 

Hv&Lv

Senior Member
Location
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Occupation
Engineer/Technician
I think it was you who in another recent thread said if it's POCO vs customer equipment, POCO wins😂

So what are the protocols for working on lines that are disconnected? To be extra sure there isn't a generator backfeed somewhere, are the lines still assumed live, and/or shorted/grounded?
All lines either in the air or on the ground are assumed live unless they are verified de-energized AND grounded.
The saying here is “it isn’t dead unless it’s grounded”
 

Hv&Lv

Senior Member
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Occupation
Engineer/Technician
Not sure why it would affect solar. If there's no power on the grid, it makes no sense to backfeed power solar or genset provided.
In fact, the reverse metering really requires power there now in order to get the backfeed to work. It wants to lead the phase.
Industry mandated anti-islanding requires it
 

hillbilly1

Senior Member
Location
Atlanta,Ga
Occupation
Field coordinator/ technical support
Not sure why it would affect solar. If there's no power on the grid, it makes no sense to backfeed power solar or genset provided.
In fact, the reverse metering really requires power there now in order to get the backfeed to work. It wants to lead the phase.

The post that came from was about having a meter that blocks back feeds, even when live.
 

drcampbell

Senior Member
Location
The Motor City, Michigan USA
Occupation
Engineer
Not sure why it would affect solar. If there's no power on the grid, it makes no sense to backfeed power solar or genset provided. In fact, the reverse metering really requires power there now in order to get the backfeed to work. ...
It might make no sense, (and be a hazard) but there's nothing to prevent someone from using a simple portable generator and a "dryer cord" from doing so. And if the outage is localized enough (seven houses and mild temperatures, perhaps) the portable generator might put enough voltage onto the line to enable the solar inverter(s) to start contributing.
 

Hv&Lv

Senior Member
Location
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Occupation
Engineer/Technician
Smart meters could incorporate backfeed detection and disconnect from the POCO. And then the POCO could be really, really slow to "reconnect".
One wouldn’t think it would be too hard to add a directional control feature to the disconnect meters. The big issue is cost. We only install these $200+ meters on houses that are disconnected often or the houses that use our prepay option.
For everyone else we use a $80 meter.
Doesn’t sound like a big difference until you replace 45-60,000 meters.
Our solar accounts get an expensive meter also.
 

Sahib

Senior Member
Location
India
Maybe NESC, if not NEC, has some rule against backfeeding such as grounding the overhead lines before any lineman working on them.
 
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