DAMN sometimes I am dense---genset hookup

-

67Dart273

Well-Known Member
Joined
Oct 14, 2010
Messages
60,035
Reaction score
33,289
Location
Idaho
After the recent windstorm I decided to GUARANTEE myself that I would NEVER need a generator again. How? Simple. Get it all hooked up "ready" and you "will never need it again" LOL

I finally decided to buy (and had to ebay, nobody local carries them) one of these sliding metal interlocks. This Allows you to legally backfeed a breaker from the genset into your fuse panel, and mechanically interlocks the fuse panel "main" to OFF while the genset is allowed ON

Bought a breaker and few pieces, STILL need a box-mount MALE receptacle to hook the genset output cord to the fuse panel. Finally orded one like this, a 20A, matches the cord I have:

4 pin, 20A, 120/240V

s-l400.jpg


AND THEN I GOT TO OVERTHINKING that "20a is not enough" (I might "someday" get a larger generator than I have now)

Until I SUDDENLY REALIZED (dummy) this is just like the 240 coming from the pole--IT HAS TWO 120V hot legs which will SHARE the load and therefore this connector can handle 40A at 120...Each connector terminal is 20A and they will add, one each leg

BUT...but bu bu b b b b b b b b b b b b but you say THERE IS ONLY ONE NEUTRAL. Well the fuse panel will take care of that just as it does from "shore" power.....some of the loads are on "one side" and some of them are on "the other." So the neutral never sees "full" return current.

So, starting at lower left I will shoe-horn the weatherflex into the genset housing to bring out to a box with the new receptacle at top center. This will mount on the frame of the genset and mate to the "thrift store cord" (4X no10) at right and the cord will fit the ebay connector to be mounted on the fuse panel on the house

genseta.jpg


The interlock. Nobody stocks these in town. You turn off the main, slide the interlock up, and that allows the genset breaker to be engaged. Since the panel is now being fed 220 just like on house power, this means any breaker can be engaged and "get juice." There will be no actual 220 loads, as the genset is not heavy enough to run the range or water heater. "I suppose" that if things got dire, it would run one burner if other loads are shed. And if all loads "except" were shed, AND I disconnected one element, "it might" heat water too LOL

gensetb.jpg
 
Last edited:
You just saved a life I'm sure of it. More than one lineman has taken a hit because of back fed power while making repairs.

Nicely done!!!
 
“DAMN sometimes I am dense”

That is why I love coming here-all you guys have outstanding advice and are fairly patient. Everyone knows something here, and many men know quite a large range of knowledge. I am grateful RRR brought me to this site. You guys are the best.
 
ideally if your panel is properly balanced the neutral to your generator would carry no current, or just a small current.

you can probably get away with one burner on the stove but the most efficient device to heat water (food) is usually your microwave. if outages are a problem, get a coleman stove and some fuel for it so you can make some warm grub if needed.
 
So, it's not legal unless you have an interlock that LOCKS the main at the same time it UNLOCKS the generator breaker. Is that right? Whoops.
 
I thought that to do it right you have to have a disconnect that opens both feeds and the neutral. If you just open the main breaker there is still a path to the transformer through the neutral wire
 
After the recent windstorm I decided to GUARANTEE myself that I would NEVER need a generator again. How? Simple. Get it all hooked up "ready" and you "will never need it again" LOL

I finally decided to buy (and had to ebay, nobody local carries them) one of these sliding metal interlocks. This Allows you to legally backfeed a breaker from the genset into your fuse panel, and mechanically interlocks the fuse panel "main" to OFF while the genset is allowed ON

Bought a breaker and few pieces, STILL need a box-mount MALE receptacle to hook the genset output cord to the fuse panel. Finally orded one like this, a 20A, matches the cord I have:

4 pin, 20A, 120/240V

View attachment 1715689329

AND THEN I GOT TO OVERTHINKING that "20a is not enough" (I might "someday" get a larger generator than I have now)

Until I SUDDENLY REALIZED (dummy) this is just like the 240 coming from the pole--IT HAS TWO 120V hot legs which will SHARE the load and therefore this connector can handle 40A at 120...Each connector terminal is 20A and they will add, one each leg

BUT...but bu bu b b b b b b b b b b b b but you say THERE IS ONLY ONE NEUTRAL. Well the fuse panel will take care of that just as it does from "shore" power.....some of the loads are on "one side" and some of them are on "the other." So the neutral never sees "full" return current.

So, starting at lower left I will shoe-horn the weatherflex into the genset housing to bring out to a box with the new receptacle at top center. This will mount on the frame of the genset and mate to the "thrift store cord" (4X no10) at right and the cord will fit the ebay connector to be mounted on the fuse panel on the house

View attachment 1715689328

The interlock. Nobody stocks these in town. You turn off the main, slide the interlock up, and that allows the genset breaker to be engaged. Since the panel is now being fed 220 just like on house power, this means any breaker can be engaged and "get juice." There will be no actual 220 loads, as the genset is not heavy enough to run the range or water heater. "I suppose" that if things got dire, it would run one burner if other loads are shed. And if all loads "except" were shed, AND I disconnected one element, "it might" heat water too LOL

View attachment 1715689330
I hate to burst your bubble but your connection setup is less than adequate for what you are trying to accomplish. I can not recommend "back feeding" any electrical panel under any circumstances.
There is only one way to safely and reliable connect an auxiliary power source to load and that is through the use of a UL approved Transfer switch manual or automatic that is installed by a qualified Electrician.
I know, people have been back feeding for years and all kinds of gizmos and non UL gadgets available, none of it meets NEMA codes and is not safe.
As a Sales Engineer for CAT and Cummins Power Systems I oversaw the installation of hundreds of generator applications, trust me you are playing with fire.
Contact a local Electrician who has performed generator work and get some professional assistance. The life you save may be your own.
 
OK, here are screen pictures I had to take since it's -10 F outside.
An electrical permit was pulled for the install & signed off on by the inspector.
And really this is interesting & kind of belongs on this sight as the Onan 30SK generator is SLANT 6 powered, that's right leaning tower of power! I will again take pictures of pictures I have of the set & post.

image000000 (72).jpg


image000000 (73).jpg


image000000 (74).jpg


image000000 (75).jpg
 
The registered Trademark Interlock sells alot of their products... We do printing for them and I see the quantities and it's an item that works for people.... And yes, in our area it will pass code. Is it the absolute right way for a different to re-power you Panels I am not sure just based on the design of how panels are powered from the poles.

One of the tricks to them that I have seen (I have installed a few for people) is the breaker schedule and if you have enough wire to move breakers around. But at the end of the day it pretty much takes injuring lines workers out of the equation. Everything else after that is above my paygrade... But they do exactly what they are intended for..

JW
 
Damn you made this way to hard. Until you have a whole house generator. Like I eventually wound up with. I now have a 20k standby by with automatic transfer switch. But before that I would turn off the main when I lost power and made up a double male heavy extension cord and plugged it into the wall socket of the circuit I wanted power in. Fridge during the day. My bedroom at night to run my C Pap and Window AC unit so I could sleep. I had a 5500 generator then.
 
I hate to burst your bubble but your connection setup is less than adequate for what you are trying to accomplish. I can not recommend "back feeding" any electrical panel under any circumstances.
There is only one way to safely and reliable connect an auxiliary power source to load and that is through the use of a UL approved Transfer switch manual or automatic that is installed by a qualified Electrician.
I know, people have been back feeding for years and all kinds of gizmos and non UL gadgets available, none of it meets NEMA codes and is not safe.
As a Sales Engineer for CAT and Cummins Power Systems I oversaw the installation of hundreds of generator applications, trust me you are playing with fire.
Contact a local Electrician who has performed generator work and get some professional assistance. The life you save may be your own.

This IS legal. The interlock prevents the main and genset breaker from being simultaneously engaged.
 
I thought that to do it right you have to have a disconnect that opens both feeds and the neutral. If you just open the main breaker there is still a path to the transformer through the neutral wire

There is no such thing as a (dedicated) neutral to the transformer. The neutral and ground amount to the same thing when it leaves the box. Actual dirt ground, "the ground stake," the neutral buss in the box, the green grounding bus, the metal box of the fuse panel, are ALL connected to the bare neutral/ ground wire going to the transformer, which is grounded to "ground" by means of a conductor down the pole. There is in fact NO POSSIBLE WAY to isolate the neutral from the green ground at the main panel. It is NEVER switched, and NEVER fused or breakered
 
So, it's not legal unless you have an interlock that LOCKS the main at the same time it UNLOCKS the generator breaker. Is that right? Whoops.
Yes and my understanding is that these interlocks are not accepted in all jurisdictions. "Local codes" and all that.
 
So, it's not legal unless you have an interlock that LOCKS the main at the same time it UNLOCKS the generator breaker. Is that right? Whoops.

Correct. Most applications I’ve seen use a transfer switch but the OP’s appears to use an interlock and only allows either the main breaker or the generator backfeed breaker to be on at the same time.

This of course, is so you do not backfeed the utility and fry some poor unsuspecting lineman. Besides that your generator would be instantly overloaded from trying to energize the neighborhood.
 
Damn you made this way to hard. Until you have a whole house generator. Like I eventually wound up with. I now have a 20k standby by with automatic transfer switch.
Is that 20K the power rating, or the price tag?
 
And to the OP, your inlet appears to be a NEMA L14-20, which as you stated is two hots and a neutral. That said, if the overcurrent protection device on your generator is higher than 20 amps, I would recommend you upgrade the inlet receptacle and associated wiring to match the generator output, especially considering it appears to be feeding a 50 amp breaker. If the generator OCPD is greater than 20 amps your inlet and wiring (assuming 12ga) is not adequately protected.
 
That's not too bad
I take it it runs of the house' gas line?
Runs on LP. And a lot of it. First time I used it it went thru 111 gal in 48 hours! Fl is the highest priced in LP! Sometimes by three times as much. After that I learned to run it on and off.
 
This IS legal. The interlock prevents the main and genset breaker from being simultaneously engaged.
"legal"
So is pissing in public as long as no one sees you.
The point I was trying to make is that the only equipment that should be in your electrical distribution system should be UL and or EU tested and approved for use, that it meet all NEMA, National, State, and Local codes, any thing elses is second rate and subject to saftey and reliablity issues.
When it comes to electrical applications I play by the rules and I suggest everyone else do the same.
Good luck
 
-
Back
Top