Generator to panel

[Wpala]

Hi
I ave a question to competent electrician to verify my logic in connecting generator to main service panel

I have a diesel heavy duty 5000 W generator, that I would like to use in case of power outage (we had few of those in last 2 years) to power some essential circuits in my home
my plan is to ground the generator with the rod to the ground, run 4 /10 wire with a female twist lock to the outdoor inlet RV type twist male outlet from there to my transfer switch all the wires to transfer switch from there only 2 hot wires to main panel where interlocking switch will be installed, my question is since the generator has neutral bonded to ground at the generator head I will run all 4 wires to the inlet at the house and to the transfer switch from there only 2 hot to main panel to break the bond, my understanding is in case there is a short the ground wire will cover the first 2 connection (inlet and transfer switch) since the main service panel has its own ground and neutral (bonded) only 2 hot wires are required to supply current please feel free to chime in if there is a problem
Thanks
Paul. W

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[aandpdan]

As shown no current will flow - unless you're running strictly 240 volt loads. You need a neutral at the panel from the generator for 120.

An interlock serves as a transfer switch so why both?

Is there any way you can remove the n/g bond at the generator?

 

[pattenp]

Just use the interlock only. Unbond the neutral and ground at gen and run 10/3 w/g wire straight from the outside power inlet to the added breaker in the service panel. This is the setup I use.

 

[ishiboo]

Hi
I ave a question to competent electrician to verify my logic in connecting generator to main service panel

I have a diesel heavy duty 5000 W generator, that I would like to use in case of power outage (we had few of those in last 2 years) to power some essential circuits in my home
my plan is to ground the generator with the rod to the ground, run 4 /10 wire with a female twist lock to the outdoor inlet RV type twist male outlet from there to my transfer switch all the wires to transfer switch from there only 2 hot wires to main panel where interlocking switch will be installed, my question is since the generator has neutral bonded to ground at the generator head I will run all 4 wires to the inlet at the house and to the transfer switch from there only 2 hot to main panel to break the bond, my understanding is in case there is a short the ground wire will cover the first 2 connection (inlet and transfer switch) since the main service panel has its own ground and neutral (bonded) only 2 hot wires are required to supply current please feel free to chime in if there is a problem
Thanks
Paul. W

[/IMG]

I wouldn't install a ground rod specific to the generator, unless it is permanently installed. And, personally, if it was right next to the house (not out on its own where it is more probable it is struck by lightning) I would still not.

The transfer switch is not needed, and all four wires including neutral/ground need to be continuous to the main panel. Use the interlock as pattenp said. If permanently installed, definitely remove the bond.

If it is not permanently installed, I would leave the neutral/ground bond at the generator (despite this being "incorrect") so it can continue to be used portably.

 

[theoldwizard1]

Just use the interlock only. Unbond the neutral and ground at gen and run 10/3 w/g wire straight from the outside power inlet to the added breaker in the service panel. This is the setup I use.

+1 !

 

[chops101]

Just use the interlock only. Unbond the neutral and ground at gen and run 10/3 w/g wire straight from the outside power inlet to the added breaker in the service panel. This is the setup I use.

+2
A 5kw genset is a small unit, no need to over complicate the design.

 

[wyliesdiesels]

I wouldn't install a ground rod specific to the generator, unless it is permanently installed. And, personally, if it was right next to the house (not out on its own where it is more probable it is struck by lightning) I would still not.

The transfer switch is not needed, and all four wires including neutral/ground need to be continuous to the main panel. Use the interlock as pattenp said. If permanently installed, definitely remove the bond.

If it is not permanently installed, I would leave the neutral/ground bond at the generator (despite this being "incorrect") so it can continue to be used portably.

No no. Thats incorrect as u said AND bad advice.

U dont want the N to G bond in two places. This can be dangerous!

How hard is it/how long does it take to remove and restore the bond? 5mins

So you feel 5mins is too mich time to spend to correct a potentially dangerous wiring setup?

 

[1/2 Cup]

As above, we are not permitted to bond the neutral and earths in the gen set nor have an earth stake in a situation that the OP has described in Australia.

Regards

 

[ishiboo]

No no. Thats incorrect as u said AND bad advice.

U dont want the N to G bond in two places. This can be dangerous!

How hard is it/how long does it take to remove and restore the bond? 5mins

So you feel 5mins is too mich time to spend to correct a potentially dangerous wiring setup?

It's all about math and statistics, which is why this situation is in the NEC in the first place. It's EXTREMELY unlikely to cause a problem. I'd rather have the additional bond in place when connected to mains for the few hours a year I need my generator attached to the house, than forget to have it in place when using it as a portable generator and having NO grounding connection to something.

Do you know exactly what makes this dangerous, and the likelihood thereof? Can you give a single example of it occurring documented anywhere? We're taught code is law and all these scenarios for death, but you really have to look at some things practically. I am willing to bet 95% of portable generators used for whole-home backup are set up with their own N-G bond, despite it being incorrect. I'd love an example of it causing injury, death or property damage. Theorize and thump code all day. There are portions of the NEC that are critical, and portions that are not. Just like there are portions of the NEC solidly grounded in science, and portions under debate.

 

[ishiboo]

As above, we are not permitted to bond the neutral and earths in the gen set nor have an earth stake in a situation that the OP has described in Australia.

Regards

No earth stake! People must be dying left and right! Such a third world country.

I am, of course, being sarcastic.

 

[wyliesdiesels]

It's all about math and statistics, which is why this situation is in the NEC in the first place. It's EXTREMELY unlikely to cause a problem. I'd rather have the additional bond in place when connected to mains for the few hours a year I need my generator attached to the house, than forget to have it in place when using it as a portable generator and having NO grounding connection to something.

Do you know exactly what makes this dangerous, and the likelihood thereof? Can you give a single example of it occurring documented anywhere? We're taught code is law and all these scenarios for death, but you really have to look at some things practically. I am willing to bet 95% of portable generators used for whole-home backup are set up with their own N-G bond, despite it being incorrect. I'd love an example of it causing injury, death or property damage. Theorize and thump code all day. There are portions of the NEC that are critical, and portions that are not. Just like there are portions of the NEC solidly grounded in science, and portions under debate.

Yes i know exactly why.

It is because of parallel metallic pathways. Just the reason why 3-wire feeders are no longer allowed.

I have no document readily available that i could point u to.

But i have seen it happen in the field.

Neutral connection became poor and because of the improper N-G bond there was potential on metal including water lines, a metal awning and the frame of an RV trailer.

The current was returning via metallic pathways instead of the insulated neutral.

Sure its rare that it happens but it does happen!

 

[Thezapper]

Well just a idea , you could leave the generator neutral and ground bonded and buy a generator 30amp or 60amp panel that will work with a bonded neutral or without

http://www.homedepot.ca/product/30-...nel-with-18-spaces-36-circuits-maximum/992420

Have it both ways, why remove the bonded neutral if its not a permanent setup, this is how I set up my temporary setup, because with 5000 watts, there's no need to go crazy as 5000 watts is not much when trying to power up a house, the panels are nice have look, Siemens makes some too

 

[olytdi]

My understanding is to bond at the genset for independent portable "field" use and not bonded for use feeding a panel for which the neutral and ground are bonded at the panel.

In other words, don't "confuse" your system with two locations for ground.

 

[1/2 Cup]

No earth stake! People must be dying left and right! Such a third world country.

I am, of course, being sarcastic.

To clarify, the earth stake and main earth connect to the Multiple Earth Neutral point in the Main Switchboard, the generator is then connected to earth at this point as well.



Regards

 

[Wpala]

Just use the interlock only. Unbond the neutral and ground at gen and run 10/3 w/g wire straight from the outside power inlet to the added breaker in the service panel. This is the setup I use.

In your diagram if you un-bond neutral from the generator head how would you ground the generator ? and your inlet connection? and have a neutral available if you only run 10/3 wire?
Paul

 

[Wpala]

It's all about math and statistics, which is why this situation is in the NEC in the first place. It's EXTREMELY unlikely to cause a problem. I'd rather have the additional bond in place when connected to mains for the few hours a year I need my generator attached to the house, than forget to have it in place when using it as a portable generator and having NO grounding connection to something.

Do you know exactly what makes this dangerous, and the likelihood thereof? Can you give a single example of it occurring documented anywhere? We're taught code is law and all these scenarios for death, but you really have to look at some things practically. I am willing to bet 95% of portable generators used for whole-home backup are set up with their own N-G bond, despite it being incorrect. I'd love an example of it causing injury, death or property damage. Theorize and thump code all day. There are portions of the NEC that are critical, and portions that are not. Just like there are portions of the NEC solidly grounded in science, and portions under debate.

Yes I read that too that for years this is how it was done and no single fatality was reported the changes came about few years back when a generators were required to have GFI protection.
Obviously this would be the simplest and easiest solution, I'm not planing on runing entire house on this and one correction to my drawing that is not a transfer switch but custom generator panel with volt meters and amp meters, the interlock switch at the main would be way to switch off main to run panel.

Here is an interesting read from someone on different forum about this

"While there are people that will vehemently disagree with me I do not see this as a huge safety factor as long as certain precautions are taken.

When a "neutral to equipment ground" bond is in place at both the generator and the service panel the "return path "(neutral currents) will return to the generator on BOTH the neutral AND the equipment grounding conductors of the generator interconnect cable. This is, by definition a code discrepancy as the equipment grounding conductor is to carry current ONLY under "fault" conditions.

Using a transfer switch (single circuit) or a transfer panel (multiple circuits) that switches the neutral-equipment ground bond from the utility service panel to the generator is one way to overcome this problem and it is the code compliant method. Unfortunately most transfer switches and panels installed and currently on the market do NOT switch the boding point.

My advice is NOT code compliant but it IS relatively safe, definitely safer than having the the parallel currents on the neutral and equipment grounds of the interconnect cable. All you need to do is NOT connect the generator equipment ground at the transfer switch/panel. What this will do is keep all the same ground fault protections offered by the service panel neutral-to-equipment ground bond in the house. You DO lose "line (hot lead) to ground fault protection ON THE INTERCONNECT CABLE between the transfer switch/panel and the generator but the actuality of a fault in this cable is very low PROVIDED you do nothing that may injure the cable such as laying it across a driveway and then running the car over it."

 

[Charles (in GA)]

In your diagram if you un-bond neutral from the generator head how would you ground the generator ? and your inlet connection? and have a neutral available if you only run 10/3 wire?
Paul

10/3 with ground.................. 4 wires total.

Charles

 

[Thezapper]

the panel that I linked on post #12 switches the neutral as well so when you switch it to generator, you can leave it un bonded at panel and leave it bonded at the genset. like I said this is a great way to keep things code compliant and safe

 

[pattenp]

In your diagram if you un-bond neutral from the generator head how would you ground the generator ? and your inlet connection? and have a neutral available if you only run 10/3 wire?
Paul

I was referring to 10/3 NM from the inlet to the panel which is 4 wires. The generator cord would be 10/4. The conductor numbering for building wire vs. cord is different. The ground is counted in cord.

 

[pattenp]

the panel that I linked on post #12 switches the neutral as well so when you switch it to generator, you can leave it un bonded at panel and leave it bonded at the genset. like I said this is a great way to keep things code compliant and safe

That panel is a solution to not un-bonding at the gen but it's $194 plus the cost of moving circuits. I just made up a bonding plug that I plug into one to the gen's outlets to reestablish the bond if I use the gen as a portable. It cost me a whole $5. I'll stick with my interlock.

 

[wyliesdiesels]

I like pattenp way the best!! Safe and easy to change!

Disabling the EGC is no better or safer than having 2 neutral bonds...

 

[Wpala]

I like your idea and sorry had a brain fart with the wires was thinking of the generator wire which is 10/4 including insulated ground, after much searching I will install heavy duty switch at the generator to bond un-bond generator for dual purpose usage and run 10/4 wire to panel with interlock switch along the way I'm making a generator sub-panel that will have volt meters installed and amp meters to monitor to hot lines see what they suppling and amp draw
Thanks
Paul