• This Forum is for adults 18 years of age or over. By continuing to use this Forum you are confirming that you are 18 or older. No content shall be viewed by any person under 18 in California.

Backup Generators

Handy chart to calculate what size generator you

http://kohlerpower.com/residential/...onNumber=13561&nodeNumber=1&contentNumber=103
lightman said:
And last but not least, hook it up correctly. Use a transfer switch!!! Forget all of the Bubba methods of double ended cords and all of that BS! Those are dangerous and are also against the National Electric Code.
Click to expand...

And as a lineman you surely had a BIG concern wanting transfer switches!
I've been told : The transformers on the poles that step say 8,000 volts down to 220 volts to run to a home do exactly the opposite also. You run your improperly connected generator without a transfer switch and that 220 volts goes BACK to that transformer and it then converts your 220 colts back to say the 8,000 volts. If this is indeed factual it must present an interesting feeling to a lineman working on an alleged 'dead' line!

Note: I said "I've been told", I am sure someone on this site could indeed verify if it is a fact or not.
 
You are correct, this is a fact. A transformer is a device with windings that changes one voltage into another. Distribution transformers are usually "step down" transformers although you do have "step up" transformers in industry. If you run 8000 volts into a transformer and get 240/120 out of it you will also get 8000 volts out of it if you run 240/120 into it. I have a small dry type transformer in my shop thats hooked up backwards so that I get 480 volts for testing motor controls with.

Lineman have safety rules and work procedures that help protect us from backfeeds once we are actually working. But the greater danger is before we get to the job site. To us and the public. The wire laying on the ground, across fences, in trees, across driveways, ect poses a hazard to anyone walking around the area. I've seen dead pets in customers yards that got on wires or touched fences that were energized. These could have easily been a person.
 
lightman said:
I'm a retired Electrical Lineman who was also a licensed Master Electrician. I live and worked in a small town. When I had to retire just about everyone in town that could afford to bought generators. They knew that I would not be replaced and that they would be served from another location, perhaps 50 miles or more away. Longer response times, longer outages, more outages, ect. Most of them bought 20kw Generacs. The newer ones are 22kw. Most have been trouble free and dependable. All except for mine! :( Mine had a bad control board and could not be programed. When that was replaced the motor threw a rod through the side of the crankcase the first time it started. (yes it had oil in it) Then the transfer switch failed. Then it started running rough and loping and had the throttle body replaced. All of this was under warranty, although it was a slow process.

I looked at all of the options really hard. I have a diesel pickup with 2 batteries and looked at inverters. The bigger ones that you see on work trucks. I have a diesel tractor and looked at PTO driven models. I've installed a few large diesel generators and seriously considered a diesel model. But a diesel is expensive to service. And they can be hard to start when its cold. I didn't want to be out in the weather connecting generators, running cords, monitoring and ordering fuel, ect and decided on the 22kw Generac running on NG. Its nice for it to start up and switch over without me having to do anything. And it does it even when we are away! I think mine was about $5000 for the generator, 200 amp transfer switch and the concrete pad. I hooked it up myself for probably $300 in material. I think the plumber charged me a few hundred dollars to connect the gas.

The guys that did the warranty work on mine told me that they work on other brands and the Generac has no more problems than the other brands. We have a Farm store here that sells Generac so thats the reason that everyone chose Generac. They also stock filters, spark plugs and a few parts for them.

And last but not least, hook it up correctly. Use a transfer switch!!! Forget all of the Bubba methods of double ended cords and all of that BS! Those are dangerous and are also against the National Electric Code.
Click to expand...
Good info lightman. Thanks
 
Papa Charlie said:
Here is a link that outlines the fuel consumption of Generac 22KW through 48KW gensets for different fuels at 25%, 50%, 75% and 100% loads. Most generators once everything is running, if sized properly will be in the 50%-75% load range. Any thing below 50% for long periods of time will cause them to load up in the cylinders.

https://assurancepower.com/aps-blog/entry/generac-home-generator-fuel-consumption
Click to expand...
thats good info to know and i could use that to help size my gas line, though I wont need to cause ill just run a 1" pipe about 3 to 5 feet and i know that will do it. Im not one to borederline size stuff. Sizing a generator is easy stuff for me.. When i said i need to bone up I meant I want to learn more about the design of generators. I just like to know how things work. Good info about the loading to- i need to keep that in mind.
Thanks for your help sparky
 
hoz53 said:
thats good info to know and i could use that to help size my gas line, though I wont need to cause ill just run a 1" pipe about 3 to 5 feet and i know that will do it. Im not one to borederline size stuff. Sizing a generator is easy stuff for me.. When i said i need to bone up I meant I want to learn more about the design of generators. I just like to know how things work. Good info about the loading to- i need to keep that in mind.
Thanks for your help sparky
Click to expand...
Look at your gas meter. If there's a pressure regulator at the inlet side, you'll have what can be considered an infinite supply. You can replace the meter with a bigger one and get a greater flow capacity. If on the other hand, there is no pressure regulator, your gas supply is limited by the size of the inlet pipe back to where it finds either a pressure regulator or a larger pipe. In the case of a 22 kW generator, that would need to be sized for 342 cuft/h of NG. This is about four to five times the demand of a typical home furnace. Natural gas has a very low delivery pressure, so large flows require large diameter and short pipes. This is something everyone kept stressing when I set up my system. The QD fittings and gas hose cost as much as the rest of the dual fuel conversion kit and I actually bought a size smaller than suggested.
 
DRNewcomb said:
Look at your gas meter. If there's a pressure regulator at the inlet side, you'll have what can be considered an infinite supply. You can replace the meter with a bigger one and get a greater flow capacity. If on the other hand, there is no pressure regulator, your gas supply is limited by the size of the inlet pipe back to where it finds either a pressure regulator or a larger pipe. In the case of a 22 kW generator, that would need to be sized for 342 cuft/h of NG. This is about four to five times the demand of a typical home furnace. Natural gas has a very low delivery pressure, so large flows require large diameter and short pipes. This is something everyone kept stressing when I set up my system. The QD fittings and gas hose cost as much as the rest of the dual fuel conversion kit and I actually bought a size smaller than suggested.
Click to expand...
DR youre a pretty sharp fellow. Basically two things i have done in my life to earn a living and that was that i was in the HVAC business for 10 years and was an electrician the rest of it. I dont know much about running motors with propane or nat gas though. So i ran alot of gasline and in my day it was all Black steel pipe. The black pipe we get these days made in india or somewhere isnt worth a crap IME. Still i got some rigid threaders for my gas pipe needs. Got some of that flexible stuff in my house that was here when we bought it and im gonna tear it out and replace with black pipe. My meters here do have a regulator before the meter. At the house my meter is rated at 250 cfh which is 250,000 btuh. my furnace is 50,000 btuh input and my water heater is 40,000. there is gas pipe going to the stove and dryer areas but i dont use those right now. 1" gas main pipe going into the house which is rated at 387 cfh for 10 feet or 387,000 btuh. Youre right looking in the chart papacharlie provided me a link to, a Generac RG022 (22kw) generator needs 324 cfh at 100% load like you said. Thats more than i expected. thats like a 324,000 btuh furnace as far as gas useage goes. Anyway a piece of 1" black pipe will handle the 22kw generator load. It will be setting out there near the gas meter and ill have to get the utility to put in a bigger meter. Next size up is 800cfh so that will handle the load. And Ill be piping it hopefully with some US made pipe if i can find some. I would have thought of checking all this stuff eventually but you brought my attention to it now which was a good thing. Thanks much for the help.

Edit:: good possibility i wont be using that big of a generator to start with. (22kw)
 
Last edited:
You must log in or register to reply here.

Upgrades & Donations

This Forum's expenses are primarily paid by member contributions. You can upgrade your Forum membership in seconds. Gold and Silver members get unlimited FREE classifieds for one year. Gold members can upload custom avatars.


Click Upgrade Membership Button ABOVE to get Gold or Silver Status.

You can also donate any amount, large or small, with the button below. Include your Forum Name in the PayPal Notes field.


To DONATE by CHECK, or make a recurring donation, CLICK HERE to learn how.

Classified Ads

Forum statistics

Threads
165,853
Messages
2,204,648
Members
79,160
Latest member
Zardek

Share This Page

Back
Top