Generator connection

[ScottA]

After the ice storm this week and power outage we started thinking we need to build in a quick way to tie in a generator to the house. Since I'm still at the rough in stage now would be the time to do it. Anyone know a good way to do this?

[Mike 870]

I have this book below that has a section on adding a plug to connect your generator to your electric panel.  I have done some of the more basic projects in the book and it seems to be pretty good, however I have not triend the generator project.

http://www.amazon.com/Ultimate-Guide-Wiring-Complete-Projects/dp/1580113508/ref=sr_1_7?ie=UTF8&s=books&qid=1233328190&sr=1-7

[Terry]

Scott, We have a "Guardian" generator connected to our house in town. It runs on natural gas or butane to start. We chose natural gas because it was readily available. The generator comes with everything you need to install and comes with a video showing you how to install. We chose to have the electrician install it for us.....we don't mess with electricity    The electrician said it was simple to install....we just had to decide which circuits we wanted on when the power went off. It will run everything except our electric heat (I guess that circuit is too large) 

It was a little pricey $2000.00 at HD; however it sure comes in handy when the power goes off.
When we build the cabin, hubby said he was going to use a generator that can be plugged directly into the special meters that our coop is now offering.

Good luck

[MountainDon]

In order to do this safely and correctly according to NEC you would need a transfer switch wired in. They can be manual or automatic. Automatic are most convenient but cost more.

The switch isolates the power grid when the switch is thrown to allow generator power into the house system. Basically foolproof. Relying on the house master breaker to do this is not a good idea as sooner or later it will be forgotten and your generator power will flow out into the grid. As well as the potential danger to power company workers who believe the lines to be dead, the power will flow to your neighbors and overload the generator.

For the actual connection between the portable generator and the house you could use an RV type of '"shore power" plug.

[glenn kangiser]

I just strip a couple pieces of wire back a couple inches - fold the ends back and jamb them in the little holes.

No - that's not a recommendation.

For on grid people they want to be sure the house is disconnected from the grid before applying power and electrocuting a lineman.  There are special transfer switches that take care of this and parts of the house can be run through it to be wired up.

Oh - I see Don said that too.  At least he didn't get the wire part.

[MountainDon]

I just strip a couple pieces of wire back a couple inches - fold the ends back and jamb them in the little holes.

......... At least he didn't get the wire part.

An old extension cord with one end snipped off works.    Done it once in a "pinch"  NOT recommended at all.       Hmmm. Actually the cabin was "wired" that way for a week or two. 

[MountainDon]

An economical automatic transfer switch can be obtained through RV suppliers. They are NOT NEC approved; if is that's a factor don't bother with this.

Iota Engineering makes a 30, 50 and a 100 amp automatic transfer switch that is used by many RV manufacturers. I've used one for years; very reliable.

One source...

http://www.solarseller.com/iota_automatic_transfer_switches__iota_power_distribution_panels__inverter_load_.htm#its___30_r

[Brandon]

Scott,

First thing to determine is what size of generator- wattage and voltage 120/220.  I have found the following people to be the authority on transfer panels http://www.gen-tran.com/.  Call them because they found me a panel that they dont advertise on their site and it saved me considerably.

Personal experience- I only opted to wire essential circuits on mine while some people want to run nearly everything like my father then complain how much gas it uses.  I have a 3000w 30amp 110volt Yamaha that is extremely quiet and with the gas furnace, refrig, tv and lights it will run nearly 24hours before fill up on 3.5 gallons.

If any one is interested I have made an aux tank out of an outboard motor gas tank which adds considerably to run times, which can be very helpful if you are without power for extended periods.  Mine will run 2.5 days between fill ups. 

Watch the exhaust people here seem to kill themselves regualrly with kero heaters in the house and generators below and open window.

[ScottA]

Thanks for all the good info. What I may do to keep the cost down is add a generator circut with maybe 2 plugs in the house wired to a pigtail outside. Maybe one by the kitchen and the other by my wifes desk. I didn't think about needing to kill the mains when the generator is on. I'm sure the transfer switch isn't cheap. I need to discuss it with the wife and see how far she wants to go. I'd need a 15kw generator to power the whole house.

[rdzone]

I have a similar setup as Brandon at my house. I run a yamaha 6600 watt generator with a gen-tran transfer panel.  It is enough power to run the whole main living area of my house (bedrooms, bathroom, kitchen) and my furnace.  If I want to run an extension cord I can even plug in my freezer.

I am the only one in my fairly large neighborhood who has any power during an outage.  I have had lots of neighbors come ask after why I have power after the power comes back on, but no one has upgraded. 

[Redoverfarm]

Scott I am one of the ones " I told you not to do that" and will probably get my hands smacked by MD but I did exactly what he said not to.  I set a 50 Amp breaker in the panel box. Run a heavy wire to an OS recp and then a pig tail to the generator.  I have a checklist on my panel box of the steps to set up and shut down.  # 1 is shutting off the main.  When the generator is running I flip the generator breaker on and then select what circuits I want power to go to.  The rest are shut off. 

The biggest problem is that I do not have any neighbors to see when the power comes back on thus I have trial & error on when it is back on.  The power Co. here will call back and let you know when they have restored power so I rely on that some. 

There are no codes applicable here so I can get by with it.  The transfer switch is a good idea but one that I didn't have to comply with nor the expense associated.  You gripe and complain about the cost of grid electric.  At one time I had to run mine for 9 days.  The grid power then was about $2.60 per day.  The generator cost my $6-8 a day not to mention hauling gas. 

[MountainDon]

Lots of if's...

If you read your instructions and follow the steps precisely on how to switch power I suppose you are okay without a transfer switch.         


I personally believe if you don't want a generator big enough to run the whole house the house/cabin should be wired in two pieces, two panels. The essentials that you can support off the generator go on the small panel, a sub of the main. The balance of the house, workshop, etc. goes off the main panel. This would more than likely be a max of a 30 amp load. If so, you could use one of the Iota 30 amp auto transfer switches on the sub. The generator connected to it. The 30 amp is only $55. When you lose main power fire up the genset. When the switch sees genset power it switches to supply genset power to that sub panel. When the grid comes back up you will have power appear at the main panels and those things will come back on. Go turn off the genset and the transfer switch goes back to taking power from the grid.

The above is cheap enough and is fine if their are no NEC inspections.



If you have a genset, keep at least a weeks worth of fuel on hand with Sta-Bil added at time of purchase. Rotate it into the car/truck every year.

[Redoverfarm]

Sort of Ironic in a way.  I no more than hit the send button on my post and the power went out.  .  Just stayed off long enough to get the hurricane lamp lite and a few candles.  Luckily the DW had just taken a pizza out of the oven so it was candle light supper for a few minutes. This will be my last post concerning power tonight.. 

[Don_P]

You are never ok powering the panel without a transfer switch, this is essentially the same as taking the safety off and pointing a rifle at a lineman. Sure I trust your finger, but not that much. My neighbor did it and had a communication breakdown between his wife and him, she threw the breaker, luckily into a live line and killed the generator. A transformer works both ways, you are not feeding 240 volts back at the lineman, he is unwittingly getting hit by over 10,000 volts. Don't do it, you can run drop cords inside and plug in appliances to a strip if necessary.

Siemens makes a breaker panel with a transfer switch in it, all in one unit. Might be worth looking at if you haven't installed your panel. I just quickly googled it up here, I'd shop if it gets serious.
http://www.homepowersystems.net/catalog.asp?prodid=566600

[glenn kangiser]

That's an interesting thought, Don P.  I see exactly what you are talking about --

Thge transformer changes 10000 volts to 240 but that little generator going backwards through the transformer makes 240 back into 10000.  My granddad was a lineman in Wisconsin and I heard of him getting fried one time ---makes nasty smoking black holes in the flesh.

[Blake]

Hello, new to the forum but thought I would chime in on this one.  I am younger,  but have been in the power generation industry for over 6 yrs. now.  4 of which were w/ a generac dealer.  Generac makes the "budget" line of guardians which were described above.  I would recommend going w/ a reliance transfer switch panel from northern tool that is sized to your needs. Unless you are willing to take a plunge for an automatic transfer switch,  it will be hard to beat the price on these.  I currently work for cummins/onan,  but while I was with the generac dealer,  I saw many diy, homemade disasters.  You need to have a lockout safety of somekind to keep the generator from backfeeding the grid.  I would strongly recommend you stay away from the guardian line of gens.  The engines are made very cheaply by generac w/ no tolerances whatsoever.  I have not installed one in my house yet, but a couple of co-workers have done theirs.  For less than $1k,  you can get a new panel from northern,  and an used onan rv takeout genset.  The onan's are far superior and if you are a maintenance freak the little motor will last you forever.  Another option is a reputable brand portable, such as honda, yamaha, etc.  If I can help you in anyway let me know.

[Don_P]

Blake, I'm new but welcome and thanks for responding. I have an older '70's exRV onan genset in my Red Green pile that will need some TLC when I get the funds to set it back up. Do you have a link to authorized centers or online parts/ manual supplies? And yes that thing was a jewel, we neglected it for years at a time and always managed to get her to life when needed. I wonder how many are out there with just a couple hundred hours on them.

After some checking I 'zaggerated, the typical incoming residential line is running at 7,200 volts, enough to give one unnaturally curly hair  .

[Blake]

After some checking I 'zaggerated, the typical incoming residential line is running at 7,200 volts, enough to give one unnaturally curly hair  .

You can log onto cumminsonan.com for service and parts dealers in your area.  The operators manuals on rv units include a small troubleshooting section,  check your model @ http://www.cumminsonan.com/rv/support/manuals,  they could possibly have it in their database.  It is an older one, so someone at your dealer should be able to help you locate the manual you need if you don't find it. And yes, you sir have a gem.  They do not make the onan engines like they did many years ago, before I was around .  I only work w/ industrial applications now,  but I do have great contacts and information if you need anything. 

As for the 7200 volts,  while going on those service calls, the generator ac voltage would never make it pass the transformer.  Problem being is the linemen could possibly get a hold of that side of the transformer. When utility meets your genset,  it turns the generator end into a ac motor,  and goes the opposite way of the engine and I've seen all kinds of nasty come from that.

Side note to those interested:  All circuits run from your generator need to be protected by their own dedicated breaker.  That is why a breaker panel is recommended on perm. applications.  The main breaker(mlcb) on the generator set will not always prevent damage to your equipment.  I have noticed some cheaper gensets breakers go as high 160% of their rated amps.

[Redoverfarm]

Blake I sent you an E-mail to your net address listed.

[ScottA]

Thanks for the reply Blake. Good info.