Kohler Generator Back feed?

[Matt N]

If the utility power is brought into the transfer switch and the back-up power is feeding the enitre 200-amp meter-main, what stops the utility wires from being back fed--from the load side of the meter--back into the wires that run to the transfer switch? What am I missing?

 

[infinity]

The transfer switch is like a multi-pole 3-way switch, in one position it connects the utility supply to the load in the other position it disconnects the utility supply and connects to the generator supply.

 

[Matt N]

The transfer switch is like a multi-pole 3-way switch, in one position it connects the utility supply to the load in the other position it disconnects the utility supply and connects to the generator supply.

I get that. But when the generator load powers up my main load center at the house, it will back feed the wires that carry the utility wires to the transfer switch. Right!?

 

[roger]

I get that. But when the generator load powers up my main load center at the house, it will back feed the wires that carry the utility wires to the transfer switch. Right!?

No, it will not. See the diagram below and notice the utility leads are completely disconnected when the generator leads are energized.



Roger

 

[infinity]

I get that. But when the generator load powers up my main load center at the house, it will back feed the wires that carry the utility wires to the transfer switch. Right!?

As Roger stated no. That's why I used the example of a 3-way switch where you can change positions but cannot have all three terminals connected at one time.

 

[Little Bill]

I get that. But when the generator load powers up my main load center at the house, it will back feed the wires that carry the utility wires to the transfer switch. Right!?

You said "meter main", just how is this all wired?
It should be:
meter main to transfer switch
Generator to transfer switch
load from transfer switch to panel
load being fed from either utility/meter or generator
Can't be back fed

 

[Frank56]

You should have a service rated transfer switch which is after your meter (load side) to the line side of your transfer switch. There is a coil between utility and generator that will sense if the utility side has power this coil will not allow back feed from the generator . Hope this helps



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[LarryFine]

If the utility power is brought into the transfer switch and the back-up power is feeding the enitre 200-amp meter-main, what stops the utility wires from being back fed--from the load side of the meter--back into the wires that run to the transfer switch? What am I missing?

You're missing exactly what a transfer switch is,and what it does.

The generator and the utility physically can not ever be connected to each other.

 

[LarryFine]

I get that. But when the generator load powers up my main load center at the house, it will back feed the wires that carry the utility wires to the transfer switch. Right!?

The correct place (electrically speaking) for the transfer switch to be inserted is between the meter and the main breaker.

Since you have a meter-main, this requires modifying the assembly by removing factory wires, considered to be a no-no.

 

[Frank56]

Are you a home owner doing electrical work if you are I would suggest hiring a Licensed Electrician before you blow yourself up.


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[roger]

Are you a home owner doing electrical work if you are I would suggest hiring a Licensed Electrician before you blow yourself up.


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Matt is an electrician and has been posting for a couple of years. Unfortunately the forum has lost profile information (including yours) in the transition to the new software.

Roger

 

[Frank56]

No problem, don’t want anyone to get hurt.


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[Matt N]

You're missing exactly what a transfer switch is,and what it does.

The generator and the utility physically can not ever be connected to each other.

No, it will not. See the diagram below and notice the utility leads are completely disconnected when the generator leads are energized.

View attachment 2551419

Roger

I completely understand how the transfer switch works. I just thought that when the generator power energizes my main panel--that it will energize my new lugs on the load side of the meter--which runs to the transfer switch.

 

[hillbilly1]

As others have said, the transferswitch is between the main at the meter, and the panel, which may or may not have a main. The three way switch analogy is right on how a transferswitch works. Look at as the common (black) screw goes to the load, while the traveler screws have the utility on one screw, with the generator on the other screw. So only one source can feed the load at a time. If it is a utility supplied meter ring type, then the switching is done inside it, choosing between the utility meter or the inlet the generator plugs into.

 

[ggunn]

I completely understand how the transfer switch works.

It doesn't seem to me that you do. The transfer switch sits between your main panel and your meter, and when the generator powers up your main panel, the transfer switch has the panel and the generator isolated from your meter. It connects the main panel to the generator and disconnects it from your meter. The transfer switch ensures that your main panel can only be connected to the generator or the grid, never both at the same time.

 

[LarryFine]

I completely understand how the transfer switch works. I just thought that when the generator power energizes my main panel--that it will energize my new lugs on the load side of the meter--which runs to the transfer switch.

Only if you wire it incorrectly. A proper installation is wired thusly:

1. Wires from meter to main breaker are interrupted, and re-routed to the T/S utility terminals.
2. New wires are run from the T/S load terminals, restoring power under normal conditions.
3. Wires from generator are run to T/S generator terminals.
4. Under normal conditions, power is routed from the utility terminals to the load terminals.
5. Upon power loss, the load terminals are switched from the utility terminals to the generator terminals.
6. The load terminals receive power from either the utility OR the generator.
7. Under no conditions are the utility and generator terminals ever connected to each other.

What "new lugs" on the meter?

 

[LarryFine]

Picture a 3-way switch. Utility is connected to one traveler terminal. Generator is connected to other traveler terminal.

Load is taken from common terminal. The two traveler terminals never connect to each other

Thus, utility and generator never connect to each other.

 

[Little Bill]

The correct place (electrically speaking) for the transfer switch to be inserted is between the meter and the main breaker.

Since you have a meter-main, this requires modifying the assembly by removing factory wires, considered to be a no-no.

Not necessarily, I just installed a genny on a service with a meter main. This was a little different set-up due to the customer's wishes to have the transfer switch and panel in the basement. So here is how I hooked it up........

Meter/main outside
Conductors from load side of MM into basement and landed on the utility side of the TS
Generator on the other side of the house, conductors from genny to generator side of TS
Load conductors from TS over to (sub)panel that was installed next to the TS

 

[LarryFine]

Yes, a standard installation can be done after the main with no problem as long as there's a sub-panel, which wasn't mentioned.

My last two generator installs involved existing mains and sub-panels; one was the ATS after the main, the other one replaced it.

 

[Matt N]

No, it will not. See the diagram below and notice the utility leads are completely disconnected when the generator leads are energized.

View attachment 2551419

Roger

Only if you wire it incorrectly. A proper installation is wired thusly:

1. Wires from meter to main breaker are interrupted, and re-routed to the T/S utility terminals.
2. New wires are run from the T/S load terminals, restoring power under normal conditions.
3. Wires from generator are run to T/S generator terminals.
4. Under normal conditions, power is routed from the utility terminals to the load terminals.
5. Upon power loss, the load terminals are switched from the utility terminals to the generator terminals.
6. The load terminals receive power from either the utility OR the generator.
7. Under no conditions are the utility and generator terminals ever connected to each other.

What "new lugs" on the meter?

Thanks for the detailed explanation.