Backfeed Generator?

[RT66DOC]

We live in hurricane country. As a matter of fact, Frances is plodding toward us now and Charley missed us by 85 miles. Our house is built like a fort - concrete block with corrugated metal shutters on all the glass; we're not in an evac zone because of distance from the beaches, elevation and really good drainage (hope I don't have to eat those words). Our biggest vulnerability is losing power for extended periods of time. Power drops out very easily around here - often during the monsoon season but is usually restored in a couple hours or less. In a hurricane situation the possibility of losing power for days to weeks is a very real.



I've been looking at generators and come up with a few thoughts on which I would appreciate feedback. A 15KW propane back-up generator with an auto transfer switch would be great... but they are in the neighborhood of $3000. Next option for $1300 would be a 7KW portable genset. (This is one of those deals where you're reluctant to spend the big bucks because the odds of really needing the thing are not great. )



This brings me to the question: Is it safe to backfeed the output from a portable generator to the main panel providing the main breaker is turned off? Several of my acquaintances around here do this. They run a 120/240V 30A pigtail to the dryer outlet, turn off the main breaker and turn on the panel circuits they want to feed.



It seems to make sense but I'm sure no electrician so I would really appreciate some info from those of you out in TDRland who know about this stuff. Thanks in advance.

 

[LandShark]

I know a number of people who have set up generators this way, Yes, it does work. Be absolutely sure the main breaker is off and lock the box and be very careful. I prefer to have a 220 outlet next to the breaker box and a test light across the mains to indicate when the main power comes back on.



Be aware that this method may not be legal and certainly not to code and you may kill someone if you screw it up.

 

[PJereb]

Sounds safe... . but it isn’t.



If the generator was running, and plugged into your dryer outlet everything would be A-ok, but if someone (maybe a "helpful" child) flipped the main breaker on it would be very bad. If you back fed the grid while line crews were out there working it is very possible you could kill or injure a lineman. If the grid was back and working, and the then the breaker got closed, your generator would be out of phase, and it would trip the dryer breaker and most likely destroy your generator.



If it was an emergency and you were going to be without power for days on end, then I would consider doing what you have described, but as an added safety buffer, remove the band and pull your electric meter from its socket, that way it is impossible to back feed.



Really you should consider a transfer switch, or if that is too expensive make up an extension cord out of heavy gauge cable, and lay it out so you can route it around your house to all important appliances, then outside to your generator. You can make up a cord with several outlets along its length with a little know-how and some cash. With some 12-4 sjoow cord you could make up a cord that would plug into your 240V receptacle on your generator. That way you would have two different 120v circuits in the same cord, and could evenly distribute the load between the two.



Peter

 

[jponder]

Exactly what I would say, pull the meter and set it somewhere inside. i've heard people say that it is illegal to pull a meter but you arenbt trying to steal anything, you are trying to be safe

 

[RT66DOC]

Thanks Gents



I think I'm leaning toward the extension-cords-running-around-the-house idea. The portable I've looked at is a Generac 7KW and is supplied with a cord - "Extenda Panel 30A Cord" - "Safely brings the full power of four heavy duty extension cords in one 25 ft length to bring power into the home. " Seems like a better way to go.



Only thing - how do you put a plug on the central A/C? Gets pretty muggy around here. Well, we do have a 120V 10K BTU window A/C in the bedroom.

 

[KMahnke]

A transfer switch is your best option of course--not the most inexpensive though. Pulling the meter is acceptable under emergency circumstances--your utility may argue with you about the definition of emergency. The open main breaker is a bad idea. Too many things to go wrong and you are putting peoples lives in jeopardy. Although we (linemen) are trained to test for and be aware of backfeed potential it does and can happen. Usually trips the breaker on the genset when you try to feed the whole neighborhood but if you live in a rural area and your particular line is isolated it will be a deadly setup for someone. The puled meter gives the utilityman a "visible" open point of isolation. It is something we use in everyday work to proof an isolation point while working on de energized lines. We will canvass an area for generators and contact the public before going in en mass to restore to be certain all sources of backfeed are isolated.



As a rule we don't work downstream of circuit breakers, enclosed switches etc unless a visible open point can be established and the circuit tested to be de energized and grounded. An open main breaker does not qualify.



Cutting a meter seal is not something you want to do under normal circumstances but a Hurricane pretty much qualifies. If you are questioned let them know you were attempting to protect their workers and you are aware of the danger. Just be sure to connect to the proper--load--side of the meter socket or main.



Be careful and good luck. The darn thing (Frances) has been sitting off our coast and

we have cabin fever from the house being shuttered up for three days now. Heading to the Keys for the day. The weathers great there!

 

[RT66DOC]

Thanks KM - Have fun in the Keys while we sit here waiting for Frances to ramp up and sit on us for the next two days. It's blowing about 50 now.

 

[KMahnke]

Wouldn't be so bad if the darn thing was moving quicker!!! We're geting more wind now than we were yesterday. Keep an eye out for "Ivan".



Kirk

 

[CChase]

My suggestion would be to put a disconnect box on the main service. Then you can throw the disconnect, lock it out, and then back feed the power into your house. The lockout would keep anybody but yourself from throwing the switch and backfeeding power to the grid.

 

[The patriot]

Yes, and

Make sure there is ONE set of keys for the lock, and you have them at ALL times.

I've thought of doing the dryer backfeed thing since I hooked up a dryer plug out in my shed, but I just run a 10 gauge 110 volt line to the house. I really just want to keep stuff in the refrigerator good, and a few lights.

Oh, BTW if nobody mentioned it, if you do the backfeed thing, make sure you run equal amounts of appliances off the two legs in the box. I'm not an electrician, this is the best I can explain it.

I'm nowhere near hurricane country, but we lose our electric a LOT here in South Jersey.

Eric

 

[lil red cummins]

i have a welder/generator plug in the garage. i DO backfeed the panel with the generator after the main has been turned off. in my house, the kids would never have thought about touching the breaker panel. i trained them well.



i also have a universal power supply (connected by insulated alligator clips, to the main lugs ahead of the main breaker) that outputs 12 volts dc. it is connected to a standard backup alarm like on a dozer. when the power comes back on, the alarm will beep. it is all mounted inside the breaker panel with only the 12 volts coming out to the beeper, so it is safe.



no it is not the safest thing in the world, but it works. a little common sense keeps it safe. if our power went out more that 2 times a year, i would consider a dedicated transfer system.



jim

 

[mazdarotary]

Why don't you go out and buy a gentran panel. They are around $300 I think and the way it works is you wire the circuits you want fed(they come in different amounts of circuits) to the gentran panel and then the gentran panel gets wired to the existing breakers. Under normal circumstances you have the switches in the gentran set in the commercial setting,and everything works normal. Then in an outage you plug the generator into the gentran panel,fire it up,and flip all the switches to emergancy mode. This will the turn on all the absolutly neccesary items you want on,like heat,fridge(gotta keep the beer cold),sump pump,lights,etc. This way there is no way of back feeding the grid,and when the power comes back on you will notice the other things will be back on,and then you can go shut the genset off. This is by no means automatic,but it is safe,and not really too expensive. Check out any local electrical distributor,or home cheap-o,loews,etc they should have one of these units. They vary in ranges from 4 circuits on up I think.

 

[RT66DOC]

After reading what all you guys have been saying I've been doing some more research and the manual transfer switch is what I've come up with as the best way to go.



Now my only problem is finding out how many watts our central A/C draws. Actually it's a heat pump - Trane XE 1200 - so I can figure what size gen to buy. Have 2 pamphlets that came with it but no info in those and no "data plate" on the unit either. Anybody have any ideas about that? Suppose I could call Trane and ask, eh?

 

[PJereb]

There should be a nameplate on the unit outside, and there should be a nameplate on the inside unit. If you can not find any information the best thing would be to get a clamp on ammeter and see how much current it draws while running. You will need a pretty good size generator to provide enough power to start that compressor motor; it probably takes a lot of current to start. The AC may only pull 10-25 amps while running (depending on the size of the unit), but it will probably take 2-4 times that amount to start the compressor.

 

[The patriot]

Volts X amps = watts.

Like PJereb said, you'll need 2-3X the running wattage to start it. Depends.

HTH

Eric

 

[RT66DOC]

Volts X amps = watts.

Like PJereb said, you'll need 2-3X the running wattage to start it. Depends.

HTH

Eric

No kidding - It's on a 240V 100A circuit and still dims the lights when it starts. My dad [RIP], the electrician, would have had disparaging remarks about that install. Doesn't seem right but I read in the Trane owner's manual that sometimes dimming the house lights when the compressor starts can be "normal". Whaddya think?



My personal acronym for remembering Ohm's Law has always been West Virginia [W=VA] Works for me. Hey, if it weren't for acronyms I'd be sweeping floors somewhere.

 

[mike r]

If you make a cord for the generator, make it out off 60 amp cable as a 7500 watt generator can supply enough surge load to start some decent sized compressors and you'll probably have to leave it a little distance from the house to account for voltage drop. A welder 50 amp plug is a good size plug as it is nearly twice the size of the dryer plug. Pulling the meter is not illegal in these instances as the lineman working your neighborhoods after the storms should be checking that there are no possible backfeeds on the transformers and branch they are working on if they are doing their job properly and most importantly, safely. The bigger problem is the inexperienced scouts that look over damaged areas before the crews get to the work area.

 

[The patriot]

No kidding - It's on a 240V 100A circuit and still dims the lights when it starts. My dad [RIP], the electrician, would have had disparaging remarks about that install. Doesn't seem right but I read in the Trane owner's manual that sometimes dimming the house lights when the compressor starts can be "normal". Whaddya think?



My personal acronym for remembering Ohm's Law has always been West Virginia [W=VA] Works for me. Hey, if it weren't for acronyms I'd be sweeping floors somewhere.

My 3 ton unit gives a slight flicker when it kicks on. I have 200 amp service.

Youre gonna need a pretty big gen set to run central A/C.

I had to memorise about 60 formulas two years back when I upgraded my engineers license. You cant take a notebook, ya gotta remember them.

Eric

 

[PJereb]

Some voltage flicker is normal.



Most utility companies engineer their system to deliver electricity as cheaply as possible. This means that they undersize conductor and transformers, and design the system so it is at or near its limits on a regular basis. This is all fine and dandy, but as the years go by, more homes get built and or remodeled, more people add and use AC, computers, fancy lighting, and all sorts of appliances add to the load on the system. Then during peak load bad things start happening, like severe voltage flicker (your lights dim when your neighbor turns on their AC), voltage drop (voltage at your outlet should be 120V+- 5%), and when things get really bad transformer fuses blow, conductors sag or fail, transformers and other equipment blows up.



If you have voltage problems call up your utility company and complain.



Insist that they send out some one to check on the problem.



They will install some sort of recording voltmeter on your electrical service, if it is out of compliance they are required by law to fix the problem, if it is on their end.



Usually that means that they will increase the size of the transformer that feeds you, or split up the circuit to two or more transformers, possibly sting new conductor, and replace any regulation equipment that is bad.







About the generator, you are going to need a whopper to fire off that AC, you may want to see if there is any sort of capacitor system that you could wire in, so that a smaller generator could start the AC compressor.



Peter

 

[The patriot]

They will install some sort of recording voltmeter on your electrical service, if it is out of compliance they are required by law to fix the problem, if it is on their end.











About the generator, you are going to need a whopper to fire off that AC, you may want to see if there is any sort of capacitor system that you could wire in, so that a smaller generator could start the AC compressor.



Peter

We have them at work. Well probably not exactly, but we record certain pumps running time, frequency of cycles, amps, etc.



About the capacitor, maybe some sort of solar UPS. Maybe one of the Hondas will work. They have both generator and inverter built into one unit.

BTW we also have UPS at work due to the sencitive (sp?) nature of chemicals in certain states. If theyre going through chemical changes, it's sometimes not good to stop it randomly. :-laf



Man this is getting more and more expensive. :-laf

Eric