# Wiring a Generator



## walhondingnashua (Jan 9, 2020)

I am figuring on wiring a generator with one of the outdoor boxes and a switch in my garage breaker box.  I want this to run back into my house to my main box to power the house in power outages.  It will be extremely convenient for my to just role the generator out of the garage, plug it in and I'm good in minutes.  It will be much more of a struggle to have to move the generator around my house near the house breaker box and run it there.   

Here is what I have already...
6/3 wire running from the garage into the house box (220; 50amp)
7800 watt generator
Outdoor 30amp 10/4 4 prong generator cord

I am looking for verification that I have to correct set up, what else I need (breaker box switch, plug, etc) and to see what other people have done to hook a generator up to their house. 

Thanks in advance...


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## Highbeam (Jan 9, 2020)

I have a similar legal, permitted setup in my home. I used all 30 amp gear for the generator inlet circuit. 

You need to install an interlock on your main panel between the main inlet breaker and the generator 50 amp breaker. 

You do have a problem at the generator inlet. As you note, the 30 amp connection is undersized. You need to use one of the higher amperage connections to match your generator inlet circuit. 50 amp stuff. You'll melt the 30 amp plug when you or someone else tries to put 50 amps through it.


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## walhondingnashua (Jan 9, 2020)

So unlike the 30amp set up you have, I should use 50 amps for everything?


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## Medic21 (Jan 9, 2020)

Highbeam said:


> I have a similar legal, permitted setup in my home. I used all 30 amp gear for the generator inlet circuit.
> 
> You need to install an interlock on your main panel between the main inlet breaker and the generator 50 amp breaker.
> 
> You do have a problem at the generator inlet. As you note, the 30 amp connection is undersized. You need to use one of the higher amperage connections to match your generator inlet circuit. 50 amp stuff. You'll melt the 30 amp plug when you or someone else tries to put 50 amps through it.


the generator breaker will open up, 7800 watt generator isn’t capable of 50amp.  

Sounds like it’s a decent easy set up.  Don’t forget to shut off the main breaker so you don’t backfeed the transformer.


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## Highbeam (Jan 9, 2020)

Medic21 said:


> the generator breaker will open up, 7800 watt generator isn’t capable of 50amp.
> 
> Sounds like it’s a decent easy set up.  Don’t forget to shut off the main breaker so you don’t backfeed the transformer.



see the mistake? You’ll burn up the 30 amp plug at 31 amps and start your house on fire before the 50 amp breaker pops.


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## Highbeam (Jan 9, 2020)

One more fun trick. Not sure if you can use an interlock to backfeed a sub panel. If you shut the main breaker off at the sub then you won’t get power back to the house main panel.

you’re into high end electrical theory here. Lots of ways to do it wrong and I’m sure you want this to be legal and code compliant.


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## Medic21 (Jan 9, 2020)

Highbeam said:


> see the mistake? You’ll burn up the 30 amp plug at 31 amps and start your house on fire before the 50 amp breaker pops.



my 8000w has a 30amp breaker man.  Your looking at a 15k to get to the 50amp range.  30amp generator plug is enough for a 7800watt generator.


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## Medic21 (Jan 9, 2020)

As far as my hook up.  I 220 outlet for the air compressor in the garage.  I just made a double male end chord with the generator plug on one end.  All I do is shut off main breaker and plug it in and fire it up.  
To disconnect it is very important to shut the breaker off and shut the generator off when it’s disconnected.  Mine is wired for a 30amp outlet for the air compressor and the small mig welder.  

8k will run the fridge, a few lights, the furnace fan, and the boiler and pumps no problem.  I have the well on so we have water but, it the well is running and the microwave is started it will trip the breaker.  8k is about the smallest to do the necessities.


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## Highbeam (Jan 9, 2020)

Medic21 said:


> my 8000w has a 30amp breaker man.  Your looking at a 15k to get to the 50amp range.  30amp generator plug is enough for a 7800watt generator.



Sorry man but do the math. 30 amps at 240 volts is just ... 7200 watts. That 7800 watt input exceeds the rating. Regardless, someone else may hook up a larger generator to the unsafe and non compliant generator circuit and burn the house down as well.

The 50 amp breaker is irrelevant when the weak link is the undersized 30 amp plug.


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## Medic21 (Jan 9, 2020)

Highbeam said:


> Sorry man but do the math. 30 amps at 240 volts is just ... 7200 watts. That 7800 watt input exceeds the rating. Regardless, someone else may hook up a larger generator to the unsafe and non compliant generator circuit and burn the house down as well.
> 
> The 50 amp breaker is irrelevant when the weak link is the undersized 30 amp plug.


When the generator has a 30amp breaker on it it doesn’t need anything larger in the circuit than 10/3 wire, if your worried about those 2.5 amps run 10ga thhn it’s rated for 35amps.  

That generator will have a 30amp breaker on it.  If you want to plan for bigger later that’s fine.  But, what he has is 30amp.  7800/240=32.5.  That’s a 30amp generator.


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## Medic21 (Jan 9, 2020)

You can run service wire rated for 200amp and put a 20amp breaker on it and it’s a very expensive 20amp circuit.  When the power source that feeds it is only capable of 30amps anything larger in the wiring is just wasting money.


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## Highbeam (Jan 9, 2020)

Medic21 said:


> When the generator has a 30amp breaker on it it doesn’t need anything larger in the circuit than 10/3 wire, if your worried about those 2.5 amps run 10ga thhn it’s rated for 35amps.
> 
> That generator will have a 30amp breaker on it.  If you want to plan for bigger later that’s fine.  But, what he has is 30amp.  7800/240=32.5.  That’s a 30amp generator.



I understand what you’re saying. You’re right about the generator. The problem is the illegal and unsafe use of 30 amp components (the plug and section of 10/3 )on a circuit protected by a 50 amp breaker.  One way to make it less illegal is to use a 30 amp breaker at the panel for this generator inlet circuit.


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## Medic21 (Jan 9, 2020)

Highbeam said:


> I understand what you’re saying. You’re right about the generator. The problem is the illegal and unsafe use of 30 amp components (the plug and section of 10/3 )on a circuit protected by a 50 amp breaker.  One way to make it less illegal is to use a 30 amp breaker at the panel for this generator inlet circuit.


It’s not protected by a 50amp breaker.  It’s a sub panel that has a 50amp circuit feeding it.  It’s protected by the 30 amp breaker on the generator.


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## Highbeam (Jan 9, 2020)

Medic21 said:


> It’s not protected by a 50amp breaker.  It’s a sub panel that has a 50amp circuit feeding it.  It’s protected by the 30 amp breaker on the generator.



nope. Breaker in the panel protects the circuit. The next guy could use a 10k watt generator so codes are written this way.


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## Medic21 (Jan 9, 2020)

Highbeam said:


> nope. Breaker in the panel protects the circuit. The next guy could use a 10k watt generator so codes are written this way.


Whatever, I’m done, you don’t understand and you surely aren’t an electrician.  I’ve installed and serviced Whole home generators and transfer switches

He is asking about everything outside the walls.  The chord going from the generator to the hookup.  




walhondingnashua said:


> Here is what I have already...
> 6/3 wire running from the garage into the house box (220; 50amp)
> 7800 watt generator
> Outdoor 30amp 10/4 4 prong generator cord



this setup is safe and will do fine. A 50amp generator chord will not plug into this type of plug So there is the safety. The generator output is protected With a breaker on every part able generator. Try to pull more than it’s rated and it pops at the generator and power goes out. That is the protection on the whole damn system when using a portable generator. A whole home generator is hard wired into the main breaker and more times than not it’s 1/2 or less than the rated amps of the main. It’s wired at the output of the generator not the rating of the main breaker.  There is a breaker in the generator that becomes the main when it’s running.


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## Highbeam (Jan 9, 2020)

Medic21 said:


> Whatever, I’m done, you don’t understand and you surely aren’t an electrician.  I’ve installed and serviced Whole home generators and transfer switches
> 
> He is asking about everything outside the walls.  The chord going from the generator to the hookup.
> 
> ...


I do understand that depending on a cheap breaker on the actual portable generator is not appropriate and is a red flag on all of your advice. 

I think you’re right about one thing, I didn’t see that only the cord was 10 gauge. That’s better. reading carefully, we don’t know exactly how this thing is wired.I think maybe neither of us actually understand this guy’s setup.

you’re obviously not an electrician either! You don’t have 220 you have 240! I bet your air compressor circuit is undersized too if it’s a typical 5 hp motor. Some people get by with illegal work but recommending it to others is risky. A suicide cord!


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## Medic21 (Jan 9, 2020)

A 5hp 240v motor is 25 amps.  It’s on a 30amp circuit.  Try again.  I will depend on the breaker everyday.  They are used stand alone all the time.


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## Medic21 (Jan 9, 2020)

And actually the ratings for a motor are 208v and 230v  if you ever actually sized one.  And our power is 228v normally.


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## Highbeam (Jan 9, 2020)

Medic21 said:


> A 5hp 240v motor is 25 amps.  It’s on a 30amp circuit.  Try again.  I will depend on the breaker everyday.  They are used stand alone all the time.


Another mistake. You size a motor circuit for the HP rating of the motor. There’s a whole section in the code that you’ve never seen.


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## Highbeam (Jan 9, 2020)

I suppose a lot depends on whether you want to follow code or you want to do something that is may be good enough. We have some electricians on this forum that are very good and helpful at giving actual code compliant advice.

I would welcome one of them pointing out my mistakes and getting the op asafe and legal generator hookup.

My generator inlet, that was permitted, also uses a 10 gauge 30 amp circuit with a 30 amp inlet plugon the house. Fed by a 30 amp cord. All the numbers match.


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## Medic21 (Jan 10, 2020)

Highbeam said:


> I suppose a lot depends on whether you want to follow code or you want to do something that is may be good enough. We have some electricians on this forum that are very good and helpful at giving actual code compliant advice.
> 
> I would welcome one of them pointing out my mistakes and getting the op asafe and legal generator hookup.
> 
> My generator inlet, that was permitted, also uses a 10 gauge 30 amp circuit with a 30 amp inlet plugon the house. Fed by a 30 amp cord. All the numbers match.



thats exactly what he has Dumbass

Unless the electrician works in your area their code advise is mute.


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## walhondingnashua (Jan 10, 2020)

I actually don't have the entire set up yet.  I don't have the plug to accept the 10/4 from the generator yet or the switch over in the breaker box that allows the generator feed into the system.
I just want to make sure I get as much advice as I can get.  Seems like I'm on the right track and I appreciate the advice.  I will make sure that I switch the main feed from the power company off when I run the generator.  (I'll probably make a reminder on the garage breaker box since the main feed is in the house)


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## zrock (Jan 10, 2020)

I will agree on the 30/50 amp plug debate up their.. Go with a 50 amp rated plug running just a few amps close to 30 plus or minus if you have to use for a extended time will melt the plug and short.. The last several years i have worked at a RV park every single 30 amp plug has been replaced several times over the years as customers were running close to the 30 amp but not enough to pop the beaker.  30 amp may be fine for a day or so but if you ever have a situation where you need to run for more days you may find yourself down as the plug overheated...  And you will be running close to the limit of that plug


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## Highbeam (Jan 10, 2020)

Medic21 said:


> thats exactly what he has Dumbass
> 
> Unless the electrician works in your area their code advise is mute.



Calm down. We’re all here to help.

oh, and it’s moot not mute.


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## Sodbuster (Jan 27, 2020)

I backfeed often, because the power in our area is sketchy. My first step is to throw the main. Then I hook up my generator to a welder outlet. with the neutrals  and the and the grounds all attached to the same bar how can this push current back into the line?


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## Medic21 (Jan 28, 2020)

The neutral and ground are bonded in the same bar to provide a safety if something happens to the neutral line.  That way you don’t become the ground path conductor.


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## Highbeam (Jan 28, 2020)

Sodbuster said:


> I backfeed often, because the power in our area is sketchy. My first step is to throw the main. Then I hook up my generator to a welder outlet. with the neutrals  and the and the grounds all attached to the same bar how can this push current back into the line?



As long as you remember to throw that main, it's fine and safe but not legal. The interlock simply forces you to shut off the main before engaging the inlet circuit and makes the backfeed legal. The inlet circuit has just a male plug. which can be used with a regular extension cord from your genset that has female receptacles.


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## semipro (Feb 1, 2020)

Highbeam said:


> As long as you remember to throw that main, it's fine and safe but not legal. The interlock simply forces you to shut off the main before engaging the inlet circuit and makes the backfeed legal. The inlet circuit has just a male plug. which can be used with a regular extension cord from your genset that has female receptacles.


I may not always be around to make sure that things are done right when the grid goes down.  I plan like I'll have to explain how to do it to my wife by text or phone call.  I also have written instructions.  
Still, the last thing I want to do is injure or kill someone that is working, likely long hours and in poor conditions, to restore my power. 
Why risk it?  An interlock just makes sense.


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## DouglasB12 (Feb 6, 2020)

walhondingnashua said:


> .....I will make sure that I switch the main feed from the power company off when I run the generator.  (I'll probably make a reminder on the garage breaker box since the main feed is in the house)



This to me is the biggest red flag issue I'm seeing. If I'm understanding it correctly - his plan requires him to *remember* to turn off his main breaker to avoid energizing the power grid. This is inherently risky. A breaker interchange panel automatically disengages your house from the electrical grid. You can draw power from the grid OR from your generator.  There is no way to have both connected at the same time. 

I don't see how he can safely hook this up by backfeeding a generator into a sub panel in the garage. The generator interchange has to be connected between the electrical meter and the main breaker panel. He can still use the idea of keeping the generator in the garage, but he would need a cord capable of reaching from the garage to the interchange panel that is between the meter and main breaker panel.

I'm sure it doesn't matter where you live, having any system that requires human intervention to avoid accidentally energizing the grid is going to be illegal and likely fatal to the lineworkers who are out trying to fix the power outage in the first place.


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## DouglasB12 (Feb 6, 2020)

Something like this is only $140 bucks and could save a life and allow you to hook up your system legally and safely.






						Reliance Generator Transfer Switch  100 Amp, 240 Volt, Model# TCA1006D | Northern Tool
					

This economical single-load transfer panel provides safe single-load transfer from generator to an office, garage or farm building ...




					www.northerntool.com


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## walhondingnashua (Feb 6, 2020)

I like that idea.  Maybe I will just install one of those and move the generator just outside the house.  For the amount of times I will be using it, it shouldn't be that big of a hassle.


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## Medic21 (Feb 6, 2020)

DouglasB12 said:


> This to me is the biggest red flag issue I'm seeing. If I'm understanding it correctly - his plan requires him to *remember* to turn off his main breaker to avoid energizing the power grid. This is inherently risky. A breaker interchange panel automatically disengages your house from the electrical grid. You can draw power from the grid OR from your generator.  There is no way to have both connected at the same time.
> 
> I don't see how he can safely hook this up by backfeeding a generator into a sub panel in the garage. The generator interchange has to be connected between the electrical meter and the main breaker panel. He can still use the idea of keeping the generator in the garage, but he would need a cord capable of reaching from the garage to the interchange panel that is between the meter and main breaker panel.
> 
> I'm sure it doesn't matter where you live, having any system that requires human intervention to avoid accidentally energizing the grid is going to be illegal and likely fatal to the lineworkers who are out trying to fix the power outage in the first place.



line workers actually ground the system they are wiring on or treat it as live.  They run into this constantly and plan for it.


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## DouglasB12 (Feb 6, 2020)

walhondingnashua said:


> I like that idea.  Maybe I will just install one of those and move the generator just outside the house.  For the amount of times I will be using it, it shouldn't be that big of a hassle.



That's why I like that idea. It is far simpler than other options that include powering select circuits in your house. I bought a Predator Generator from Harbor Freight that puts out 8750 watts. That should be more than enough to run my 1400 sf house and the well. I have to run some more numbers, but I think I can even run the central AC as well - as long as the dishwasher or dryer isn't run.


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## burnham (Feb 6, 2020)

Medic21 said:


> line workers actually ground the system they are wiring on or treat it as live.  They run into this constantly and plan for it.




 No, we don't.


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## Medic21 (Feb 7, 2020)

burnham said:


> No, we don't.


Every accident scene I have ever been on where a pole was taken down, there have been hundreds is 25 years, they have grounded the wires after isolating the circuit.  All before we could do our thing.  Specifically for the possibility of a generator coming on.  

I figured that was an industry standard since it was two different companies.


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## semipro (Feb 7, 2020)

Medic21 said:


> Every accident scene I have ever been on where a pole was taken down


At least where we live, the outages are rarely caused by a pole being taken down.  Usually, its ice/wind/trees taking down some wires or causing a short.


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## burnham (Feb 7, 2020)

Medic21 said:


> Every accident scene I have ever been on where a pole was taken down, there have been hundreds is 25 years, they have grounded the wires after isolating the circuit.  All before we could do our thing.  Specifically for the possibility of a generator coming on.
> 
> I figured that was an industry standard since it was two different companies.



On an accident pole, yes, usually.  During a storm, not always.   It's two very different situations.  Yes, we are always supposed to either work something like it's live, or ground it.  That works on an accident pole, or during the first couple days of a storm.   But after working three or four sixteen hour days in a row, a lot of that goes out the window.   Guys are still wearing rubber gloves, but end up coming in contact with wires, or handling wires on the ground that aren't grounded.  I'm not saying it's right, but that is what happens.   In a storm situation we're trying to restore power to as many people as fast as we can.  You're always thinking of those who don't have heat, or water.  Or someone with kids, who's losing a freezer full of meat.   We always will de-energize, test, and ground a circuit before police/fire have to extract someone, or work on them in a car.  

  I see a lot of people who don't really know what they're doing hooking up generators.  A lot of them are of the opinion that the lineman is just going to plan for a backfeed.  That's not always the case, and it's a poor attitude.  Nevermind the fact that they can backfeed lines on the ground that the general public has to deal with.   

 When I was a kid, we didn't have a generator, and lost power often. It wasn't a big deal before the internet came along.  Now everybody under the sun has enough money for a 65" TV on the wall, and a generator.  Nobody wants to pony up for a proper transfer switch to run the generator.   I can't count how many people I've talked to who know just enough to be dangerous.


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## Medic21 (Feb 8, 2020)

burnham said:


> On an accident pole, yes, usually.  During a storm, not always.   It's two very different situations.  Yes, we are always supposed to either work something like it's live, or ground it.  That works on an accident pole, or during the first couple days of a storm.   But after working three or four sixteen hour days in a row, a lot of that goes out the window.   Guys are still wearing rubber gloves, but end up coming in contact with wires, or handling wires on the ground that aren't grounded.  I'm not saying it's right, but that is what happens.   In a storm situation we're trying to restore power to as many people as fast as we can.  You're always thinking of those who don't have heat, or water.  Or someone with kids, who's losing a freezer full of meat.   We always will de-energize, test, and ground a circuit before police/fire have to extract someone, or work on them in a car.
> .



Really? You just admitted that the safety rules are ignored when your busy. That would be like me just jumping in because I think power is dead. Not too smart.

and you proved what I said was right.  You’re supposed to do it but, you don’t...

The reason I have a job in emergency services...


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## DouglasB12 (Feb 8, 2020)

Medic21 said:


> Really? You just admitted that the safety rules are ignored when your busy. That would be like me just jumping in because I think power is dead. Not too smart.
> 
> and you proved what I said was right.  You’re supposed to do it but, you don’t...
> 
> The reason I have a job in emergency services...



May I point out that Burnman was talking about introducing human error after working long hours, day and night, in harsh weather conditions. Mistakes can and do happen.  We are also talking about human error that can happen when a generator is back fed into a homes power supply. To condemn one situation, but excuse the other one is..... beyond stupid.  Especially when people are back feeding because they are either too lazy or cheap to hook up their generator properly.

Really - what *valid* justification is there for someone to not hook their generator up properly and safely?


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## Medic21 (Feb 9, 2020)

DouglasB12 said:


> May I point out that Burnman was talking about introducing human error after working long hours, day and night, in harsh weather conditions. Mistakes can and do happen.  We are also talking about human error that can happen when a generator is back fed into a homes power supply. To condemn one situation, but excuse the other one is..... beyond stupid.  Especially when people are back feeding because they are either too lazy or cheap to hook up their generator properly.
> 
> Really - what *valid* justification is there for someone to not hook their generator up properly and safely?


I didn’t read human error.  I read being lazy not following safety rules, and trying to justify it. When in the end all it is is a way to get yourself killed. I showed this to a local lineman and his response, And he’s a safety manager, was it that was one of his employees he be fired for a post like that.

That would be no different than me as a firefighter ignoring safety practices because I’m tired and don’t wanna follow them during overhaul.  As a chief that would’ve been an automatic suspension. There is never an excuse to bypass safety.


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## Medic21 (Feb 9, 2020)

Not to mention OSHA is not gonna blame the dumbass homeowner.  They’re going to fine the company, blame the employee, and good luck getting any benefits out of it


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## burnham (Feb 9, 2020)

Medic21 said:


> Really? You just admitted that the safety rules are ignored when your busy. That would be like me just jumping in because I think power is dead. Not too smart.
> 
> and you proved what I said was right.  You’re supposed to do it but, you don’t...
> 
> The reason I have a job in emergency services...




Aren't you the one here stating you backfeed your service by opening the main, and using a double male cord (not chord)?   You know your set-up is not legal, and they refer to that as a suicide cord for a reason?

 I'm not ignoring any safety rules, and what I do would be nothing like _you jumping in because you thought the power is dead _ because I know what I'm doing, and you know just enough to be dangerous.    Even a grounded line can have potential during a backfeed or a fault, because the ground is just a parallel path.


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## Medic21 (Feb 9, 2020)

burnham said:


> Aren't you the one here stating you backfeed your service by opening the main, and using a double male cord (not chord)?   You know your set-up is not legal, and they refer to that as a suicide cord for a reason?
> 
> I'm not ignoring any safety rules, and what I do would be nothing like _you jumping in because you thought the power is dead _ because I know what I'm doing, and you know just enough to be dangerous.    Even a grounded line can have potential during a backfeed or a fault, because the ground is just a parallel path.



I do use a double male cord.  I have a switch to kill the outlet I plug it into.  And it feeds the circuit I need fed to have heat and the fridge work.  I don’t need to open the main since I open the breaker
For that circuit.  As long as I shut off the outlet and the generator at the same time it’s safe.  It’s not about legal or illegal it’s about code.  There are no laws about it.  

I installed a dual lug meter base this fall with a 100amp sub panel in my basement. Yes, I installed it because I do know what I’m doing. Plans are to move the essential circuits and switch to a standby generator with automatic transfer switch.

As far as your choice to violate safety rules, because “you know what you’re doing.”  I had an EMS run a few years back.  By the time we got him down from the bucket and to the trauma center he lost both arms and had died on me three times. I’m sure he knew what he was doing also But, that was an accident, Equipment failure, not willful disregard for set standard safety rules.  I’m sure you check your gloves and equipment everyday right?  But it wouldn’t matter since you admitted you know what your doing and choose to not treat downed lines as live, after a few shifts that is.


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## walhondingnashua (Jun 12, 2020)

I'm researching the kits or the parts I'm going to need to set up this system.  I can generally search for a switch and an outdoor plug but I don't specifically what I need.  My main breaker box is in the house.  I want the plug outside and will run a wire into the transfer switch.  Would anyone that has set up this system mind sending me some pictures of your set up or what you bought?


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## moresnow (Jun 25, 2020)

Great discussion guys. Thank gad we are socially distancing via the net! 
To the op. Do this once. Do it correctly. No worries! Carry on.


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