electrical tech question, non-valk

[FryeVRCCDS0067]

I'm an industrial electrician but I'd like a 2'nd opinion on this.

I've got a small, 240Volt 30 amp generator. I'm planing on installing a 240 Volt weatherproof outlet on the back of my house. Then making up a "highly dangerous  ) 30 amp extension cord with two male ends.

My thinking is that during our frequent power outages (country living) I could shut off the main breaker on our breaker box and the breakers to most of the household circuits. Then use the male-to-male extension cord to power my breaker box with my generator, after making sure the main breaker is shut off.

This seems so simple I keep thinking there is something wrong with the idea I'm not seeing.

I understand that if I didn't turn off the main breaker I'd be trying to power the local grid and posing a hazard to utility workers, but as I said, I'd shut off the main breaker to prevent this.

I also understand that my puny generator couldn't power much, but by shutting off the correct breakers I could easily keep my load under 30 amps.

Am I missing something?

[Joe Hummer]

Hey Frye,

I done about the same with my generator...even with the breaker set up.  I have used it once or twice as needed and have not had a problem with it.  For the most part, I have only been able to power up my fridge and freezer and a few lights...but those are the main things I want to keep going during a prolonged outage. 

I rely on seeing the neighbor's lights on to tell me that I have power again.  I need to hook up a light to the incoming power to to indicate when power is back on. 

Joe

[98valk]

I'm not an electrician by trade but need to know enough when working with 440v that powers the equipment I work on and I did stay at a holiday inn once.  
I suggest that u need to install a power transfer switch most local codes require it.

some reading
this sounds like what u want to do. backfeeding from the utility when they restore power is the danger.
http://www.electricgeneratorsdirect.com/stories/13-How-NOT-to-Connect-a-Portable-Generator.html

http://www.electricgeneratorsdirect.com/stories/59-How-to-Connect-a-Portable-Generator-to-a-Home.html

power inlet box needed also per most codes.
http://www.electricgeneratorsdirect.com/stories/2-How-to-Pick-the-Perfect-Power-Inlet-Box.html

[Dr Bobs Patient]

Hey Frye don't fry!

The tranfer switch is the better and safer way to go.  What you propose can be done as long as the utility power is disconnected from your home.  I have a small generater just big enough to run the frig and TV.  That's really all I need and I use extension cords run to the outside to the genny to do this.

Transfer switches will not allow both the utility and genny power to be on at the same time.

DBP

[tank_post142]

far be it from me to advise you to do anything not compliant with code. but please remember you will have to feed into the panel below the main breaker probably through a 50 amp (or larger)double pole breaker.insure you run wiring and plug capable of handling much higher amps than you are feeding it. that way when you upgrade to a bigger generator you don't need to do it over. you will upgrade your gen set guaranteed.

[Dorkman]

Presume you are also being careful about properly grounding your system.  You will be picking off 120v each side to neutral.   Also, is the power of the generator clean enough to run the TV?  The frig and lights should be no problem, but electronics don't like surges or dirty power. 

Transfer switches also depend upon the generator getting up to speed before the transfer occurs, i.e. starting automatically in most cases.  Is your generator capable of this if you decide to go the transfer switch route?  If not, you probably need a manual switch between your generator and the panel and/or be real careful with the household breakers, i.e everything off when you power up.

I also stayed at a Holiday Inn once.  So have other Valkyrie owners.  Definitely related.

[valky1500]

Presume you are also being careful about properly grounding your system.  You will be picking off 120v each side to neutral.   Also, is the power of the generator clean enough to run the TV?  The frig and lights should be no problem, but electronics don't like surges or dirty power. 

Transfer switches also depend upon the generator getting up to speed before the transfer occurs, i.e. starting automatically in most cases.  Is your generator capable of this if you decide to go the transfer switch route?  If not, you probably need a manual switch between your generator and the panel and/or be real careful with the household breakers, i.e everything off when you power up.

I also stayed at a Holiday Inn once.  So have other Valkyrie owners.  Definitely related.

A transfer switch, by design, does not allow the generator to backfeed through the main. It doesn't rely on you to remember to switch anything. The transfer switch mechanically either allows your selected house circuits to get power from the main or to get power from the generator, but not both at the same time. It is dummy proof.

Another reason to have a transfer switch is so you can manage your loads. For example, if you have a 6 circuit transfer switch. One leg of the 240 feeds circuits 1-3, and the other leg feeds circuits 4-6. You balance the draw when you assign those circuits, and you have 2 meters on the transfer switch to view the draw off of each leg. In order to run a 240, you tie circuits #3 and #4 together so you are drawing from both legs.

A real danger with the proposed method is having 30 amps at 240V on the end of a male plug. There's a reason why the powered side of an outlet or cord is female.

Spend the money and have a transfer switch installed, or run extension cords.

I use this setup: http://powerequipment.honda.com/generators/connecting-a-generator-to-your-home

Those house circuits already provide the proper grounding.   

[valky1500]

Bear in mind that utilities take back feeding very seriously. If they find voltage on a line which is supposed to be dead, (1) they will search the neighborhood for houses which are lit up, ask to see your transfer switch, and if you don't produce, (2) they will report you to code enforcement.

If one of their men is injured, skip step two, and go directly to lawyers. The burden of proof is on you, and your liability is nearly unlimited, to the extent of your net worth.   

[6tigo]

Easiest and most economical approved method is a generator interlock kit.  Very sinple (I  like that) and safe.

You install a generator feed breaker under your current main breaker.  After install in order to power your panel you turn off your main, you then slide a plate provided in the kit that blocks the main from being switched on. At the same time it moves out of the way of the feed breaker allowing it to be turned on.

Google Generator Interlock, lots of info.

[FryeVRCCDS0067]

Thanks guys. 

[FryeVRCCDS0067]

Easiest and most economical approved method is a generator interlock kit.  Very sinple (I  like that) and safe.

You install a generator feed breaker under your current main breaker.  After install in order to power your panel you turn off your main, you then slide a plate provided in the kit that blocks the main from being switched on. At the same time it moves out of the way of the feed breaker allowing it to be turned on.

Google Generator Interlock, lots of info.

Basically the very same thing I was going to do. Thanks.

[Jess from VA]

Frye, I have that very setup.  5000W generator (Coleman Vantage overhead valve, cast iron sleeve, low oil shutoff) in the shed, handmade (from electrical supply) dual male 4-prong 220 twist ends on a flexible heavyweight extension (8-10 gauge?) (about 40 feet).  

15yo, I had a full 200Amp heavy-up to the house to replace my antiquated 100amp screw-in fuse service by a licensed contractor.  Had them do some custom work, run 220 circuit to deck, and had them wire me in an outdoor 220 four prong female box which is located exactly outside the house from the 220 box in my basement utility room.  What I cannot explain is how they routed the generator feed to the main 220 box, though I have been told they backfeed the 220 generator line to the box by splitting it into two 110 amp circuits inside the box.  

They did not install a transfer switch, and they did pull a permit, thou in my county, permits are just for revenue, the county never did come out and actually inspect any of the extensive work.

My start sequence is:  drag heavy-ass generator out in front of open shed door (exhaust aimed out), gas and start generator, go inside and knock off the main, all 220s, and half the rest of the house.  First plug extension onto the back feed on the back of my house, and last plug in the extension into the generator.  

Then I go back in the house, and slowly bring up the rest of the house, but no 220s.  I had some brown out issues on my upstairs circuits when I first did this by leaving the whole house on (minus the 220s) when I first plugged in the generator to house circuit.  I run dual surge protection to all of my electronics, TV, FIOS, computer, etc at all times.  This setup allows me to run about everything in the house (two fridges, 250W constant - 450 surge), TV, computer, lights inside and out, gas furnace, but I do not run things like ceramic heaters, coffeemaker, microwave or other high draws while on the generator.

Only way I can tell when power is returned to the neighborhood is to see lights coming on in neighbors houses.  This usually happens in big ice/rain/wind storms at night so having one of those headband mounted LED lights is a must for stumbling around in the pitch black soaking storm while playing with 220.      

[FryeVRCCDS0067]

Frye, I have that very setup.  5000W generator (Coleman Vantage overhead valve, cast iron sleeve, low oil shutoff) in the shed, handmade (from electrical supply) dual male 4-prong 220 twist ends on a flexible heavyweight extension (8-10 gauge?) (about 40 feet).  

15yo, I had a full 200Amp heavy-up to the house to replace my antiquated 100amp screw-in fuse service by a licensed contractor.  Had them do some custom work, run 220 circuit to deck, and had them wire me in an outdoor 220 four prong female box which is located exactly outside the house from the 220 box in my basement utility room.  What I cannot explain is how they routed the generator feed to the main 220 box, though I have been told they backfeed the 220 generator line to the box by splitting it into two 110 amp circuits inside the box.  

They did not install a transfer switch, and they did pull a permit, thou in my county, permits are just for revenue, the county never did come out and actually inspect any of the extensive work.

My start sequence is:  drag heavy-ass generator out in front of open shed door (exhaust aimed out), gas and start generator, go inside and knock off the main, all 220s, and half the rest of the house.  First plug extension onto the back feed on the back of my house, and last plug in the extension into the generator.  

Then I go back in the house, and slowly bring up the rest of the house, but no 220s.  I had some brown out issues on my upstairs circuits when I first did this by leaving the whole house on (minus the 220s) when I first plugged in the generator to house circuit.  I run dual surge protection to all of my electronics, TV, FIOS, computer, etc at all times.  This setup allows me to run about everything in the house (two fridges, 250W constant - 450 surge), TV, computer, lights inside and out, gas furnace, but I do not run things like ceramic heaters, coffeemaker, microwave or other high draws while on the generator.

Only way I can tell when power is returned to the neighborhood is to see lights coming on in neighbors houses.  This usually happens in big ice/rain/wind storms at night so having one of those headband mounted LED lights is a must for stumbling around in the pitch black soaking storm while playing with 220.      

Thanks Jess, that's exactly the info I was looking for. It looked to me like it should work but I wanted to hear from someone who was doing it.
Thanks again,
Frye

[Patrick]

I basically do as you want to. I turn off the main house feed breaker and back feed from the barn thru a welding plug and shop breaker panel so it ends up being routed thru 2 sets of breakers.

[Jeff K]

I do the same thing I have the death plug with two male ends. I added a small beeper to the main line with a switch to let me know when the power came back on.

Just be 100% sure you have the main shut off so you don't light up the guys working on the line. I do it all the time.

[Patrick]

" Death plug " , interesting name.  I do the same, 30 amp male to a 50 amp male.  The 'beeper' in the main line is a good idea, I'll look for one..

[98valk]

to eliminate the "DP", consider a "power inlet". 

here is one i.e.
http://www.amazon.com/ParkPower-150BBIWRV-White-Power-Inlet/dp/B002QALLOQ

they are available in different amps.

[JP in SC]

I'm an industrial electrician but I'd like a 2'nd opinion on this. ...


...This seems so simple I keep thinking there is something wrong with the idea I'm not seeing.

I understand that if I didn't turn off the main breaker I'd be trying to power the local grid and posing a hazard to utility workers, but as I said, I'd shut off the main breaker to prevent this.

I also understand that my puny generator couldn't power much, but by shutting off the correct breakers I could easily keep my load under 30 amps.

Am I missing something?

As an electrician you already know that it will work and I'm guessing you already know that it's not the right way to do it since you're asking the question.

It's one thing to try something that may bite you, but there's a tremendous liability when it can put others at risk. Are you ready to live with the consequences if things do fubar and you hurt or kill a utility worker repairing the lines?

Is the money saved by taking shortcuts worth the potential for harm?

I have to agree with what has already been stated.

Spend the money and have a transfer switch installed, or run extension cords.

[Robert]

I have a 16k generator does the whole house and is wired permanently in. Most panels make a breaker interlock panel just for your make and model panel. You can just get a breaker, wire that into a 4 prong outlet and use that as the inlet for the gen hookup. The wiring of course has to be the right gauge for the run and power a outside outlet requires a weather proof outlet but it can be virtually anywhere. Being a electrician it will be easy for you to pull permit to make it legit and the interlock panel is legal in most states as long as its made for that panel is certified and sometimes has to be the panels mfg only. My gen did come with a transfer switch and I decided not to go that route. Although it would make it fully automatic it would have required a new panel and substantial rewiring which after having new 200 amp service put in I was not so wiling to change. The transfer switch was 100 amp and would have required only wiring certain circuits to it. With the way I have it set up now the gen is wired into a breaker that can only be turned on by mechanically shutting off the main then flipping the breaker. One or the other can only be on. The mechanical interlock is nothing more than a piece of metal that mechanically stops the the main and links one other breaker of choice.  The other breakers are not affected and this way it powers the whole house, I don't have to be selective on the circuits I turn on and I have full control of when the gen flips on. I really don't need to have the automatic feature I would rather turn it on myself. Its really a pain to pull out certain circuits to wire into a transfer switch and although they make a panel and switch in one usually its a panel then the transfer switch in another panel and it gets to be a bit messy. The way you are thinking is ok but the mechanical interlock is the way to go. There are many on line companies that make them if your panel is old and will even custom make them with the certification needed or like I did just order one from the mfg of the panel. They are pretty common easy,cheap, usually meet code and easy to install takes all the guess and chance out of the equation.

[Gavin_Sons]

Hey frye, whatever you do, do not back feed to your electric service. The electric company will own everything you have if someone working on the lines gets hurt or killed. My best friends dad got killed from someone that was back feeding one of their lines when he was working on it. Best way is to have a seperate panel for your generator with each breaker you want to feed jumped to that panel from the existing one. Make sure all yor breakets are off including the main breaker so there is no chance in back feeding the service. Then all you have to do is fire up the generator and flip your switches in the new box on.

[FryeVRCCDS0067]

I'm an industrial electrician but I'd like a 2'nd opinion on this. ...


...This seems so simple I keep thinking there is something wrong with the idea I'm not seeing.

I understand that if I didn't turn off the main breaker I'd be trying to power the local grid and posing a hazard to utility workers, but as I said, I'd shut off the main breaker to prevent this.

I also understand that my puny generator couldn't power much, but by shutting off the correct breakers I could easily keep my load under 30 amps.

Am I missing something?

As an electrician you already know that it will work and I'm guessing you already know that it's not the right way to do it since you're asking the question.

It's one thing to try something that may bite you, but there's a tremendous liability when it can put others at risk. Are you ready to live with the consequences if things do fubar and you hurt or kill a utility worker repairing the lines?

Is the money saved by taking shortcuts worth the potential for harm?

I have to agree with what has already been stated.

Spend the money and have a transfer switch installed, or run extension cords.

Every day, my life and the lives of my co-workers depends on me knowing how to identify, shut-off and lock out the correct breakers. Along with making sure I can't be killed by superheated steam or crushed by stored mechanical energy.

I see absolutely nothing wrong with this method but was so amazed at how much money people spend on idiot proofing such a simple thing that I thought perhaps there was a problem with the ground still being common with the grid. I was wondering specifically if these special switches break the ground to the grid in addition to the two feed legs or if there was some other odd quark concerning electron flow which I was missing.

Obviously if I was a lineman I'd feel better knowing that the guy who can't change his own oil has some kind of lockout device to protect me from his mistakes if he's running a generator. It's exactly the same reason that I keep my lockout key in my pocket when I'm working on something that could kill me if it was started. It's to protect me from them.

I'd also virtually guarantee you that those same lineman hook up their own generators in much the same way I asked about.

I know we have a lot of technical expertise on this board and that's what I was looking for. Purely to verify my understanding of electron flow.

By the way, I really like the "death cord" thing.

Thanks,
Frye

[Gryphon Rider]

It might not always be you playing with your setup.  Make it foolproof for the next homeowner, or for the person house-sitting while you're on vacation, or for your your ___ who is at home when the power goes out when you are in the hospital recovering from ___.

[Jess from VA]

The principle reason for my setup is because after three days of rain (groundwater to 18" from surface), my very nicely finished basement will flood if the sump pump is inoperable (like from power loss).

I can trust NO ONE to run my system.  All trips are planned around long range weather reports. 

[Tx Bohemian]

I'm not an electrician by trade but need to know enough when working with 440v that powers the equipment I work on and I did stay at a holiday inn once.  

Not sure I'd listen to this guy, he was supposed to stay at a holiday inn EXPRESS to qualify!!!







Ok, just joshing ya!

This topic is very intresting to me as I heard that this can be done and was thinking about rigging my house up for this also. 
A few years ago I did buy a 5500 watt generator for power loss and haven't had to use it yet. (knockin on wood)

However we very seldom lose power for any length of time so I'm thinking I'll just run extension cords when/if it does happen. 

[Patrick]

We do have winter house-sitters, but, I have specific written directions and have them perform the required operations and make sure they are comfortable and correct with it. The written directions have to be used as a 'pre-flight/ post-flight' checklist. I used this method, but, the friends haven't yet. I don't have a problem if the power is out for a couple days if we are away and usually it isn't out for that long anyway. Frye does have a good point regarding grounds though, even though I don't think there is a problem if everything is wired correctly.

[Jess from VA]

OK, while we're on the subject, perhaps someone can answer this.

In addition to the risk to lineman, I have heard it said that if you leave the main on or turn it on while the setup is operating, and the power is restored to the house, it would smoke/destroy your generator in a few seconds.  True?

[98valk]

OK, while we're on the subject, perhaps someone can answer this.

In addition to the risk to lineman, I have heard it said that if you leave the main on or turn it on while the setup is operating, and the power is restored to the house, it would smoke/destroy your generator in a few seconds.  True?

read the first link I posted
"As near as we could figure from piecing together the story (and the molten pieces of equipment) when the electrical service was re-energized by the utility it took them three tries to get their fuse and switch to hold in; but by that time the generator had melted/shorted 'shooting' flames out from the alternator windings! "

[Jess from VA]

I thought so...... I will never be testing this however. 

Fifteen or more years with my system and no issue, other than the carb getting gummed up in a generator used 0-4 times per year.  It is now drained of fuel, tank and bowl, after each use.   

[FryeVRCCDS0067]

OK, while we're on the subject, perhaps someone can answer this.

In addition to the risk to lineman, I have heard it said that if you leave the main on or turn it on while the setup is operating, and the power is restored to the house, it would smoke/destroy your generator in a few seconds.  True?

If it didn't blow the generators circuit protector soon enough then it would indeed let the smoke out of it. The reason is that your generators power would be "out of phase" with the power company's supply.

If you take two wires from the same buss-bar on your breaker-box and connect them together nothing will happen. (but I still wouldn't do it!) because they're both on the same phase so there is no voltage potential between them. If you did the same from one buss bar to the other you'd make a loud boom and a lot of sparks because the two legs of 120 volts are 180 degrees out of phase with each other. That's were 220 comes from. If they were some variant of 180 degrees out of phase then you'd have some odd voltage potential between them which could be predicted mathematically if you knew the phase relationship.

If your generator wasn't in exact phase with the power company (not a chance of that happening) it would be the same as shorting the bus bars together. If you've ever noticed burn marks on a breaker-panels bus bars then you know someone had an exciting day.   

My sump pump and freezer are my concerns too. In past years I've been several days without power and wound up with wasted venison and a flooded basement. I've got a new heat-pump down there now and can't afford to buy another one.

[Jess from VA]

Thanks, I only have a general idea what you're talking about, but I get it.  I'm not bad with simple harry homeowner house electric (wired my two sheds), but I really suck at auto electric...... I have let the smoke out of enough wires, I don't even try anymore.  I have a circuit tester, but a wet finger is nearly as good for me.   

I had a weeks' leave from CA to find a home here in VA ('92), and I chose poorly.  Guy said the basement never leaked, but he lied.  It took about 6 months for the first extended rain, and one night I had to lug everything (worth anything) up the stairs and wet dry vac the floor for 15 hours. 

My neighborhood was built in '59-60, and they used the absolute cheapest materials available for every single part of the builds.  The terra cotta drain system had long since crumbled, and did not take water to the sump hole; so it came up inside the cement block foundation (to 18" from surface), found cracks, ran down the finished walls and out the baseboard. 

So I stripped the basement, and had the crew that uses electric jackhammers cut the floor out 18" all around the exterior walls, hand dig to the footers, and put in a proper french drain with 6" PVC and large gravel, backfill, and repair the concrete.  The block foundation can still leak, but a drip edge attacked to a seam crack left in the floor (inside the finished wall) takes any water back to the drain system.  Nothing like having a major industrial project inside your home.  That basement is the family room, the best living space in the house.  Dry as a bone since the repair.

The foundation had been wet for many years, and caused the single story slab to my three level split to crack down the middle, and the one story part of the house to separate from the two story side, just slightly.  All dry now for many years, and most things repaired (not the slab).  But I can never let a power outage take out my sump system after a multiday rain, or I will flood again. Thus the generator project.

I actually tried finding my seller, who moved to Fl, but I think he knew I would be looking for him, so he hid really well.  He said he had painted the interior before he sold....... he did, take two gals of latex and mix it with 15gal of water and painted.  It was my first and only home (lived in military housing before that), and I have learned a lot in 20 years........ enough that I want to move to a pole barn on a slab if I ever move again.     

[FryeVRCCDS0067]

but I really suck at auto electric...... I have let the smoke out of enough wires, I don't even try anymore.  I have a circuit tester, but a wet finger is nearly as good for me.

Auto and motorcycle electric is way harder than home and most industrial as far as I'm concerned. I usually just keep the bike running while I shake, push and pull stuff till I find the problem. 

[Mr.BubblesVRCCDS0008]

I have a 5500 watt generator and a cord just like you're talking about. If you throw the main and the heavy user breakers A/C, electric stove, hot water heater it will work. I ran for two weeks on this set up after Ike and everything worked ok. I back fed my from a welding plug in the garage. I did find out because it was about 75 feet from garage to breakerbox and back to garage that the drop was too much to run the washer, gas dryer. I had to run them straight off the gen. I ran 9 ceiling fans and one freezer and two fridge and all the lights we needed off this set-up. At night just a few fans and lights and a small window air conditioner.  I also run my camper with this gen and cord. The copper thieves cut my cord off my trailer so I mounted a plug inside the trailer so I can open the little door and plug the cord in where it is out of the weather. I always plug the dead end into the outlet  before powering up the gen.  I'm not saying it is code but it will work.

[valky1500]

I have a 5500 watt generator and a cord just like you're talking about. If you throw the main and the heavy user breakers A/C, electric stove, hot water heater it will work. I ran for two weeks on this set up after Ike and everything worked ok. I back fed my from a welding plug in the garage. I did find out because it was about 75 feet from garage to breakerbox and back to garage that the drop was too much to run the washer, gas dryer. I had to run them straight off the gen. I ran 9 ceiling fans and one freezer and two fridge and all the lights we needed off this set-up. At night just a few fans and lights and a small window air conditioner.  I also run my camper with this gen and cord. The copper thieves cut my cord off my trailer so I mounted a plug inside the trailer so I can open the little door and plug the cord in where it is out of the weather. I always plug the dead end into the outlet  before powering up the gen.  I'm not saying it is code but it will work.

For that size generator to avoid the unwanted voltage drop your feed wire should be within 30 feet of the generator and inlet box. Shorter is better.

Connecting a generator by wire such as this to a camper is fine but for your house Do everybody a favor and just run extension cords until you can do this right.   

[Mr.BubblesVRCCDS0008]

I now have a plug in a box right next to the breakerbox no problem at all.

[paps350]

OK. I'll try to answer some of these questions and address some of the comments. I can speak to this topic as I was an electrical lineman for 37 years.
1. The initial post said he wanted to connect a 30 amp generator through his panel box. A generator that size will not run too many things but would be fine to run the essentials. ( frig. furnace blower if a gas furnace, a few lights. Anything with a motor uses whats called start up current which consider if your frig. uses 7 amps running current the start up may be 11 amps. That said you don't know when the motor on frig. or furnace will be starting or if they could start at the same time.
2. As to the double male cord the reason its called a death plug is the exposed prongs on the house end will be hot. If the cord worked loose and layed there and someone contacted it or fell against something metal a fire could be the result.
3. I could go on and on but sometimes too much info is bad. I have been up and down the eastern United States after all types of storms and there have been way too many FATALITIES caused by improper use of a generator. The cause of them is when connected to a house electrical sytem and is not isolated from the power grid it sends 120 volts onto the grid and transformers normaly lower the voltage from primary volts 23000 down to 120 volts but if a generator feeds 120 volts backwards through it then it sends 23000 volts onto the grid. So even though we test for backfeeds from generators we can't take for granted someone improperly connected a generator after the test.
4. Anytime I heard a generator running i approached the homeowner and asked to verify the connection many take exception to the inquiry. ( engineers are the worst).

 I hope I have shed some light ( no pun intended) on this topic but the best way is always the right way. Even though there are manys ways to connect to your house the right way is an automatic  transfer switch or use extension cords. Unless you have a decent sized generator stick with cords.

[Joe Hummer]

OK. I'll try to answer some of these questions and address some of the comments. I can speak to this topic as I was an electrical lineman for 37 years.
1. The initial post said he wanted to connect a 30 amp generator through his panel box. A generator that size will not run too many things but would be fine to run the essentials. ( frig. furnace blower if a gas furnace, a few lights. Anything with a motor uses whats called start up current which consider if your frig. uses 7 amps running current the start up may be 11 amps. That said you don't know when the motor on frig. or furnace will be starting or if they could start at the same time.
2. As to the double male cord the reason its called a death plug is the exposed prongs on the house end will be hot. If the cord worked loose and layed there and someone contacted it or fell against something metal a fire could be the result.
3. I could go on and on but sometimes too much info is bad. I have been up and down the eastern United States after all types of storms and there have been way too many FATALITIES caused by improper use of a generator. The cause of them is when connected to a house electrical sytem and is not isolated from the power grid it sends 120 volts onto the grid and transformers normaly lower the voltage from primary volts 23000 down to 120 volts but if a generator feeds 120 volts backwards through it then it sends 23000 volts onto the grid. So even though we test for backfeeds from generators we can't take for granted someone improperly connected a generator after the test.
4. Anytime I heard a generator running i approached the homeowner and asked to verify the connection many take exception to the inquiry. ( engineers are the worst).

 I hope I have shed some light ( no pun intended) on this topic but the best way is always the right way. Even though there are manys ways to connect to your house the right way is an automatic  transfer switch or use extension cords. Unless you have a decent sized generator stick with cords.

Hey Paps...

First a comment...excellent post...and very interesting information. 

I have a question...If you isolate the main breaker on the panel...does that stop the possibility of back-feeding the grid? 

Joe

[valky1500]

OK. I'll try to answer some of these questions and address some of the comments. I can speak to this topic as I was an electrical lineman for 37 years.
1. The initial post said he wanted to connect a 30 amp generator through his panel box. A generator that size will not run too many things but would be fine to run the essentials. ( frig. furnace blower if a gas furnace, a few lights. Anything with a motor uses whats called start up current which consider if your frig. uses 7 amps running current the start up may be 11 amps. That said you don't know when the motor on frig. or furnace will be starting or if they could start at the same time.
2. As to the double male cord the reason its called a death plug is the exposed prongs on the house end will be hot. If the cord worked loose and layed there and someone contacted it or fell against something metal a fire could be the result.
3. I could go on and on but sometimes too much info is bad. I have been up and down the eastern United States after all types of storms and there have been way too many FATALITIES caused by improper use of a generator. The cause of them is when connected to a house electrical sytem and is not isolated from the power grid it sends 120 volts onto the grid and transformers normaly lower the voltage from primary volts 23000 down to 120 volts but if a generator feeds 120 volts backwards through it then it sends 23000 volts onto the grid. So even though we test for backfeeds from generators we can't take for granted someone improperly connected a generator after the test.
4. Anytime I heard a generator running i approached the homeowner and asked to verify the connection many take exception to the inquiry. ( engineers are the worst).

 I hope I have shed some light ( no pun intended) on this topic but the best way is always the right way. Even though there are manys ways to connect to your house the right way is an automatic  transfer switch or use extension cords. Unless you have a decent sized generator stick with cords.

Hey Paps...

First a comment...excellent post...and very interesting information. 

I have a question...If you isolate the main breaker on the panel...does that stop the possibility of back-feeding the grid? 

Joe

When a transfer switch is incorporated...

and was installed by a verifiable licensed electrician...

There can be no possibility of back feeding in the grid on either side.

... and Yes it does remove the liability on your part which is the whole point of it all.

It includes the fires or any other damage that may occur as the result of using your generator as were mentioned in the statement above.

[FryeVRCCDS0067]

OK. I'll try to answer some of these questions and address some of the comments. I can speak to this topic as I was an electrical lineman for 37 years.
1. The initial post said he wanted to connect a 30 amp generator through his panel box. A generator that size will not run too many things but would be fine to run the essentials. ( frig. furnace blower if a gas furnace, a few lights. Anything with a motor uses whats called start up current which consider if your frig. uses 7 amps running current the start up may be 11 amps. That said you don't know when the motor on frig. or furnace will be starting or if they could start at the same time.
2. As to the double male cord the reason its called a death plug is the exposed prongs on the house end will be hot. If the cord worked loose and layed there and someone contacted it or fell against something metal a fire could be the result.
3. I could go on and on but sometimes too much info is bad. I have been up and down the eastern United States after all types of storms and there have been way too many FATALITIES caused by improper use of a generator. The cause of them is when connected to a house electrical sytem and is not isolated from the power grid it sends 120 volts onto the grid and transformers normaly lower the voltage from primary volts 23000 down to 120 volts but if a generator feeds 120 volts backwards through it then it sends 23000 volts onto the grid. So even though we test for backfeeds from generators we can't take for granted someone improperly connected a generator after the test.
4. Anytime I heard a generator running i approached the homeowner and asked to verify the connection many take exception to the inquiry. ( engineers are the worst).

 I hope I have shed some light ( no pun intended) on this topic but the best way is always the right way. Even though there are manys ways to connect to your house the right way is an automatic  transfer switch or use extension cords. Unless you have a decent sized generator stick with cords.

Hey Paps...

First a comment...excellent post...and very interesting information. 

I have a question...If you isolate the main breaker on the panel...does that stop the possibility of back-feeding the grid? 

Joe

Yep. Good info, it's easy to forget transformers work both ways. But, the real question is, does shutting off the main breaker isolate the home from the grid?

[valky1500]

OK. I'll try to answer some of these questions and address some of the comments. I can speak to this topic as I was an electrical lineman for 37 years.
1. The initial post said he wanted to connect a 30 amp generator through his panel box. A generator that size will not run too many things but would be fine to run the essentials. ( frig. furnace blower if a gas furnace, a few lights. Anything with a motor uses whats called start up current which consider if your frig. uses 7 amps running current the start up may be 11 amps. That said you don't know when the motor on frig. or furnace will be starting or if they could start at the same time.
2. As to the double male cord the reason its called a death plug is the exposed prongs on the house end will be hot. If the cord worked loose and layed there and someone contacted it or fell against something metal a fire could be the result.
3. I could go on and on but sometimes too much info is bad. I have been up and down the eastern United States after all types of storms and there have been way too many FATALITIES caused by improper use of a generator. The cause of them is when connected to a house electrical sytem and is not isolated from the power grid it sends 120 volts onto the grid and transformers normaly lower the voltage from primary volts 23000 down to 120 volts but if a generator feeds 120 volts backwards through it then it sends 23000 volts onto the grid. So even though we test for backfeeds from generators we can't take for granted someone improperly connected a generator after the test.
4. Anytime I heard a generator running i approached the homeowner and asked to verify the connection many take exception to the inquiry. ( engineers are the worst).

 I hope I have shed some light ( no pun intended) on this topic but the best way is always the right way. Even though there are manys ways to connect to your house the right way is an automatic  transfer switch or use extension cords. Unless you have a decent sized generator stick with cords.

Hey Paps...

First a comment...excellent post...and very interesting information. 

I have a question...If you isolate the main breaker on the panel...does that stop the possibility of back-feeding the grid? 

Joe

Yep. Good info, it's easy to forget transformers work both ways. But, the real question is, does shutting off the main breaker isolate the home from the grid?

It seems that his reasoning has eluded you somewhere with what the retired lineman said.

The transformer is what isolates from the grid (substation). No power goes back out and past the transformer, it's one way in.

The whole point of the matter and where the danger lies at is when the lines are light up andhot because an illegally connected generator that causes a back-feed anywhere and up to and in between transformers. Not after that. It can be several city blocks served by those transformers. 

[Gryphon Rider]

The transformer is what isolates from the grid (substation). No power goes back out and past the transformer, it's one way in.

So, what prevents a step-down transformer from working in reverse, becoming a step-up transformer?