Generator circuit protection

[Roy Suomi]

I've got a question about circuit protection for my old Homelite generator and home appliances. I want to run a total of 4 cords to 4 separate recepticals to power up the furnace, freezer, fridge, and some low wattage lights. I have some double pole- double throw 32 amp knife switches. China buggers but covered and insulated. I want to tie these in to the house wiring for the furnace. The connection box on the furnace is plumb full of wires and not big enough to add this switch to it. I was going to cut and tie into the power lead going to the furnace, switching both the power and neutral and tying the grounds together. [ making all connections inside a work box ]. I have 12 ga. wire [cords] on the switches with a 15 amp male plug on one lead for generator cord , center connections to furnace and the other lead connect back to utility power [ house breaker] that I cut into. Doing it this way I don't have to worry about back feeding and killing some poor lineman somewhere. My issue is I'd like to fuse or breaker each individual circuit that the generator is hooked up to. What's my best way of doing this ? I can't find fuse holders that will support tube style 15 amp fuses and don't want to go the 220 route. Thanks..

 

[buickanddeere]

Trying to save money and make this project simple
Is making it costly and impractical .
Just install an interlock between the main breaker and the top right breaker on the main panel .
Connect the generator . Flip the interlock and beakers . Open the breakers to the electric water heater , electric clothes dryer and electric kitchen stove .
Good to go without a mess of extension cords , complex switching , dark rooms and dead receptacles .
Lower cost , simpler and will work better .

 

[MarkB_MI]

Why don't you want to "go the 220 route"? Is your generator 120V-only?

There are few things more aggravating than 120V extension cords running all over the place. One of the best things I ever did was to upgrade to a 6500W 240V generator and install a whole-house transfer switch. If you're on well water, getting power to your pump is as important as running the furnace.

 

[John T]

Roy, lots of questions and as its electrical you will likely get a ton of responses, but for now at least I will ONLY address one critical safety issue, maybe later discuss how to properly connect and provide overcurrent protection.

You state: I was going to cut and tie into the power lead going to the furnace, switching both the power and neutral and tying the grounds together.

BE AWARE

1) In the event you choose to switch the UnGrounded (Hot) Conductor as well as the Grounded (Neutral) Conductor and configure your genny as a "Separate Derived Source" it needs to have a Bonded Neutral (many come from factory with a Floating Neutral) PLUS it requires bonding to a proper "Grounding Electrode" including but not limited to a "Made Electrode" such as driven into the earth ground rods.

2) There can ONLY BE ONE Neutral/Ground Bond. If you were to tie the utility and genny grounds together and your home service already has a Neutral/Ground Bond and you do as the above YOU MAY BE IN VIOLATION OF THE NEC

BOTTOM LINE you need to do it one way or the other IE The genny configured as a Separate Derived Source' OR NOT If its NOT configured as a Separate Derived Source and you ONLY switch the UnGrounded (Hot) and Bond the Grounded (Neutral) Conductors THEN THE GENNY NEEDS A FLOATING NEUTRAL PLUS the home/utility Equipment GroundING Conductor must be bonded to the gennys case/frame !!!!!!!!!!!

NOTE Its extremely important to determine if the genny should be configured with a Bonded or a Floating Neutral !!!!!!!!!!!!

HOW TO CONNECT A good proper safe and NEC approved method would be to use a proper transfer method (eliminates any possible backfeed) versus running several extension cords and perhaps a sub panel or other method to power the furnace in case of a power outage. There can be different methods all approved and its YOUR money YOUR home YOUR safety and YOUR choice but please do it safely. DO NOT take my word for this, Im rusty being a long retired power distribution design engineer so consult trained professional electrical engineers and electricians is my advice when it comes to fire and life safety

Its NOT that expensive or rocket science and SAFE to use a proper safe approved TRANSFER METHOD (stand alone switch or onboard slide out interlock) and use a SUB PANEL to feed critical circuits such as a furnace or freezer etc with proper connection to a generator having EITHER a Bonded or a Floating Neutral as required SUBJECT TO the NEC rules. (see above)

Best wishes, be safe

John T

 

[Dusty MI]

Another way, and this will only transfer the circuits that you want to run with your generator.
A transfer switch is a double pole double throw switch.
Add a sub panel beside your main panel. Put a main in it, addd a 2 pole breaker, sized to protect your generator, add an inter lock linkage to the main and generator breakers. Then add the circuits that you want to be able to power up with the generator.

Dusty

 

[bc]

The alternative you have would be plug in a coffee pot and the tv into the generator. Have a generator big enough to run an 80 inch TV. Then have a supply of Boston Irish Cream liquor for a mix. Grab a blanket or two and watch the Chiefs win again. Be just like you were sitting in the top row of Arrowhead Stadium. The louder you yell and the more you drink, the less you will notice the cold. Have a good day. Chiefs play at noon central time today.

 

[Billy Shafer]

Trying to save money can cost you. I have seen that to many time. As
you say. Do it the proper way or don't do it.

 

[John T]

Great plan my electrician sparky friend. A sub panel for chosen critical circuits (fridge, water pump, freezer etc) is a simple easy and
affordable way to provide backup genny power in an outage plus coupled with a safe proper no backfeed transfer switch is straight forward
method. You in Zephyrhills ?? Im in High Springs now then Bushnell working my way south

John T

 

[Russ from MN]

When we had a gas furnace installed I just wired it with a heavy cord, they don't use that much power. Maybe 2 times in the 15 years we lived in that house we had extended power outages, I can step over a cord once in awhile, it worked fine for us. A cord to the furnace, coffee pot, and a lamp, fridge and freezer if the power is off for very long. Keep it simple!

 

[ss55]

In the long run you will wind up either removing or re-doing the shortcut before you sell the property. Unless potential buyers plan to raze the building, any cobbled up, kludged, farmerized, work-arounds raise all kinds of red flags causing buyers to question everything else about the property and to look for other half-fixed problems.

Is the problem that you want to hook up more loads than the generator can run if they all turn on at the same time?

 

[Dusty MI]

(quoted from post at 07:53:22 12/13/20) Great plan my electrician sparky friend. A sub panel for chosen critical circuits (fridge, water pump, freezer etc) is a simple easy and
affordable way to provide backup genny power in an outage plus coupled with a safe proper no backfeed transfer switch is straight forward
method. You in Zephyrhills ?? Im in High Springs now then Bushnell working my way south

John T

John,
We are staying home until this nnalert thing is under control.

Dusty

 

[Roy Suomi]

OK.. I got it. I didn't want to do this, but I guess I'll have to go transfer switching box and go a bigger genny.. Thanks..

 

[MarkB_MI]

> OK.. I got it. I didn't want to do this, but I guess I'll have to go transfer switching box and go a bigger genny.. Thanks..

Well, you don't HAVE to do anything. But once it's in, you won't regret installing a transfer switch.

 

[Billy Shafer]

When the power goes off and you have no backup. And the wife is on your butt. You will really understand.

 

[John T]

Good choice safety wise speaking even if sure other (even if perhaps NOT code approved) methods could work and get you by. Its still important to correctly choose a Floating versus a Bonded Neutral, but that's not difficult and there's no real cost either way.

Glad to help and thanks for the feedback

John T

 

[buickanddeere]

(quoted from post at 13:30:17 12/13/20) OK.. I got it. I didn't want to do this, but I guess I'll have to go transfer switching box and go a bigger genny.. Thanks..

Dont have to go with a larger generator . Just the transfer switch is critical .

In my personal experience . A transfer switch for the entire panel works better , costs less , takes less time and is less complicated . Just open the breakers to the high demand loads .
Just out of curiosity , what is the existing generator ?
120V can be supplied into a 240V transfer switch without a problem .

 

[PJH]

Russ - I wired our heat system with a #12-3 cord too. It plugs into an outlet in the basement and unplugs easily if generator power is needed. I also power our refrigerator wall outlet the same way. I can unplug it in the basement too. Our generator is only 3500 watts, so I have to manage our power consumption.

We've had two extended power outages since 1998.

 

[Dusty MI]

By having a sub panel for just the circuits that need to run off the generator. If you are not home or laid up, Almost anyone could start the generator and switch to the sub panel run by the it. Which keeps from over loading the generator.

Dusty

 

[buickanddeere]

(quoted from post at 16:35:55 12/13/20)
By having a sub panel for just the circuits that need to run off the generator. If you are not home or laid up, Almost anyone could start the generator and switch to the sub panel run by the it. Which keeps from over loading the generator.

Dusty

Not a fan of the sub panel as this requires yanking wires out of original panel . Some wires are too short and require junction boxes .
Also the number of circuits are limited. This leaves low demand but important circuits as room lights, smoke detectors and most receptacles non functional.
Far simpler to just transfer the entire panel. Less disturbance to the wiring. Just switch the breakers off for the high demand loads such as the electric clothes dryer, electric water heater and the electric kitchen range .
Bonous is that if someday a larger generator is obtained. The home electrical system is not bottlenecked with a rinkydink sub panel.

 

[Roy Suomi]

Question.. What is a bonded neutral as opposed to a floating neutral.. This is Greek to me.. I always thought a neutral was just a white wire that attached to the breaker box neutral bar.

 

[Roy Suomi]

No , we watch the "Brownies" here..

 

[JayinNY]

I put in a transfer switch, easy to install, safe and no problems with it,

I only have to plug one cord into the generator, then pick which circuits i need to run.

 

[John T]

Some gennys come from the factory with a Bonded, others a Floating Neutral.

If its Bonded, if you use an ohm meter or a continuity tester at a 120 Volt receptacle, the Neutral and Ground are connected (closed circuit, low near zero resistance)

If its Floating, a continuity or ohm meter will show an OPEN connection from the Ground to the Neutral in a receptacle. They are NOT bonded

The way a generator should be wired depends on if your transfer switch switches BOTH the Hot and Neutral orrrrrrrrr if you only switch the Hot and bond the Genny and utility Neutrals together (in that case the genny needs a Floating non bonded Neutral and the utility Ground bonds to the gennys case/frame). If you switch BOTH Hot & Neutral the genny should have a Bonded Neutral and its case/frame tied to a ground rod.

Sooooooooooo the answer depends on what Transfer switch you use (how many poles) and if you switch the Neutral or not. If not switched and genny and utility Neutrals are tied together FLOAT THE NEUTRAL ON THE GENNY dont bond it to case/frame.

Clear as mud Im sure lol but most non electricians and non engineers dont understand this so dont feel bad

John T NO Warranty Im long retired as an EE and rusty on the latest codes