Is this safe???!!!

[wade0000]

Hello,
I am in the process of running a completely separate circuit from my unattached garage that has the solar system in it, into my house.

This separate circuit will only have 2 or 3 outlets inside the house and will be used only for emergency lighting, emergency fans, etc.

HOWEVER.... I was just thinking, that since the power from the batteries is relatively small, could I hook up my small gas generator (2000W) and as an option if the power is going to be out long or the panels are covered up by heavy snowstorm... that I instead run the 2000W gas generator INTO THIS DEDICATED CIRCUIT.

There is obviously a switch between the power connect so it would not back feed the breaker and inverter. I know I would need to be careful and not have both on at once.. .but wanted to hear what you fine people thought about the idea.. Any yes, I know that a male with male cord is not the ideal. Grounding would have to be double checked with regard to the generator for sure.

Here is a sketch...

 

[GLC]

Yes, as long as there is a disconnect switch between the inverter and where the generator is hooked up so there would be no possibility of both on at the same time. I would though add an ac breaker or a fuse between the generator and the outlets in the house.

Question though. What about the ground from the generator and your receptacles? Does the generator have a bonded neutral? Is your generator grounded? Matter of fact is your inverter grounded? If so where and how?

 

[Rider]

The problem with reverse feeding is forgetting to open or close a switch. There is no safety other than your memory.
If you're going to run wiring inside for multiple outlets, do it right and put in a breaker panel. It can be small, just a couple of breakers. Wire the inverter as tho it were the grid feed, and wire the generator thru the breaker panel on an interlock breaker. The genny can never provide power at the same time the inverter could.

Yes, it's a few $ more to do it this way, but you're sure there will never be a conflict between inverter and genny, no chance of damage to any devices. It also provides you with an upgrade path if you want a bigger genny, bigger inverter, more outlets.

 

[GLC]

I actually installed a manual transfer switch like this on my setup between the house, generator and solar inverter.
Manual transfer switch

 

[FilterGuy]

Theoretically what you describe is doable, but I certainly would not call it safe.

1) The plug on the cable from the generator would have to be a male plug. This would leave 120V exposed across the plug.

2) if you ever forgot to turn of the switch in the garage and hooked up the generator it would be very bad

3) There might be a problem if the switch was on an the generator was plugged in but not running.

A much better solution would be to put a transfer switch in that selects between the inverter and generator.



You could even do a red-neck transfer switch like I did at a cabin once

 

[boondox]

Yup, do it so that the inverter and genny can't be hooked up at the same time. FG's way is good and cheap, since you have to do a manual switch in order for it to work at all.

And some legit questions have been asked about ground/neutral bonding and there is no ground rod in your drawing. These issues must be addressed as well. The ground and neutral should be bonded in only one place. Check and see if your inverter and/or genny have a bond between them.

 

[FilterGuy]

Yup, do it so that the inverter and genny can't be hooked up at the same time. FG's way is good and cheap, since you have to do a manual switch in order for it to work at all.

And some legit questions have been asked about ground/neutral bonding and there is no ground rod in your drawing. These issues must be addressed as well. The ground and neutral should be bonded in only one place. Check and see if your inverter and/or genny have a bond between them.

Good point about the ground bonding.

 

[wade0000]

Good point about the ground bonding.

You all are the best.

The main solar system is of course grounded... but I see now that I would need to make sure this circuit is also has it's protection since it is split off... but would have still been grounded in my original drawing since the ground passes in, thru and to the grounding bar of the solar power system.

Need to think on this. Must study more... THANKS!~

 

[snoobler]

If the inverter isn't an inverter/charger, replace it with one.



Now the genny can charge the batteries and supplement them as needed.

 

[FilterGuy]

That works too!

 

[GLC]

You all are the best.

The main solar system is of course grounded... but I see now that I would need to make sure this circuit is also has it's protection since it is split off... but would have still been grounded in my original drawing since the ground passes in, thru and to the grounding bar of the solar power system.

Need to think on this. Must study more... THANKS!~

Remember even though the generator may have a ground lug on the frame, it may not have a bonded neutral. Without a bonded neutral, hooking up a ground wire to the ground lug is pointless and will not ground the unit in case of shock. Also without a bonded neutral, It will not activate any breakers or fuses on the generator if it does not have a bonded neutral. You can check this by, without the generator running, put a meter connecting / touching the neutral and the ground in the electric receptacle to see if there is continuity or checking connection between the neutral on a elec plug and the grounded lug on the generator. Now if you do have a bonded neutral on your generator, great. You can use a grounded rod to ground your generator using the lug on the frame and everything will be ok. If you do not have a bonded neutral, you can simply purchase a male plug that will plug into a elec receptacle that will make it have a bonded neutral or you can make one yourself. Just use a male plug and place a wire connecting the common to the ground. This you do not screw up. Only connect the neutral to the ground. Do not hook up ground to the load / hot wire on the male plug. Like I said, DON'T HOOK UP THE GROUND TO THE LOAD/ HOT WIRE ONLY TO THE NEUTRAL! If you are confused about this, let someone else qualified to make this plug or just purchase a plug.

 

[wade0000]

It's a Pulsar 1800/2300 portable unit. It shows it has a ground connection bottom left... But I'll study the owners manual the specs on that...

 

[GLC]

Yes pretty well all generators do. The problem still is, does it have a bonded neutral, meaning is the ground lug on the frame and ground prong on the receptacle tied to the neutral somewhere in the wiring? If not you will need to create it.

 

[FilterGuy]

Remember even though the generator may have a ground lug on the frame, it may not have a bonded neutral. Without a bonded neutral, hooking up a ground wire to the ground lug is pointless and will not ground the unit in case of shock. Also without a bonded neutral, It will not activate any breakers or fuses on the generator if it does not have a bonded neutral. You can check this by, without the generator running, put a meter connecting / touching the neutral and the ground in the electric receptacle to see if there is continuity or checking connection between the neutral on a elec plug and the grounded lug on the generator. Now if you do have a bonded neutral on your generator, great. You can use a grounded rod to ground your generator using the lug on the frame and everything will be ok. If you do not have a bonded neutral, you can simply purchase a male plug that will plug into a elec receptacle that will make it have a bonded neutral or you can make one yourself. Just use a male plug and place a wire connecting the common to the ground. This you do not screw up. Only connect the neutral to the ground. Do not hook up ground to the load / hot wire on the male plug. Like I said, DON'T HOOK UP THE GROUND TO THE LOAD/ HOT WIRE ONLY TO THE NEUTRAL! If you are confused about this, let someone else qualified to make this plug or just purchase a plug.

Actually, it is more nuanced than that. (And there is a lot of confusion out their about this)

https://www.csemag.com/articles/choosing-between-3-pole-and-4-pole-transfer-switches/

If a power source ties neutral to ground, it is considered a 'separately derived' source.
If a power source does not tie neutral to ground it is *not* considered a separately derived source.
You can tie a non seperatly derived source to the system through a transfer switch without bonding neutral and ground as long as the other source has neutral and ground permanently bonded.

If a generator does not bond Neutral and ground, it is not considered 'separately derived' In this case you bond Neutral and ground at inverter and your transfer switch only switches the Hot wire.

If a generator does bond neutral and ground, it is not considered 'separately derived' In this case you bond Neutral and ground at inverter and your transfer switch switches both the Hot and Neutral wires.

The ground wire is never switched.

 

[GLC]

Actually, it is more nuanced than that. (And there is a lot of confusion out their about this)

https://www.csemag.com/articles/choosing-between-3-pole-and-4-pole-transfer-switches/

If a power source ties neutral to ground, it is considered a 'separately derived' source.
If a power source does not tie neutral to ground it is *not* considered a separately derived source.
You can tie a non seperatly derived source to the system through a transfer switch without bonding neutral and ground as long as the other source has neutral and ground permanently bonded.

If a generator does not bond Neutral and ground, it is not considered 'separately derived' In this case you bond Neutral and ground at inverter and your transfer switch only switches the Hot wire.

If a generator does bond neutral and ground, it is not considered 'separately derived' In this case you bond Neutral and ground at inverter and your transfer switch switches both the Hot and Neutral wires.

The ground wire is never switched.

You are correct but I bet he will not understand you terminology.

 

[wade0000]

You are correct but I bet he will not understand you terminology.

I'd have to study this with a fine toothed comb to understand. man, that is confusing.

 

[FilterGuy]

Here is a simplified explanation that should work for you.

1) Make sure your ground is permanently tied to neutral at the inverter
2) Is the ground tied to neutral on the generator?
No: Your transfer switch needs to switch the Hot between the generator and the inverter. The neutral and ground should not be switched.
YES: Your transfer switch needs to switch the Hot and Neutral between the generator and the inverter. The ground should not be switched.

How to check to see if ground is tied to Neutral at the generator:
With nothing hooked to the generator and the generator not running put an ohm meter between the ground pin and Neutral. If there is little or no resistance then ground is tied to Neutral.

Edit: added the 'not' to the 'yes' case sentence

 

[Rider]

With nothing hooked to the generator and the generator not running put an ohm meter between the ground pin and Neutral. If there is little or no resistance then ground is tied to Neutral.

If there is no commonality between the two, it will also show no resistance. Most meters don't distinguish between infinite resistance and a dead short, both show 0 ohms.

If the meter has an audible tone setting for shorted probes (continuity), a sound indicates neutral/ground is common. No tone means they are not common.

 

[BiduleOhm]

Most meters don't distinguish between infinite resistance and a dead short, both show 0 ohms.

I never saw a meter doing that (even a 5$ one).

They'll show 0 (or close to 0) Ohms for a short, and OL (for overload) or another similar symbol for an open circuit.

 

[boondox]

I never saw a meter doing that (even a 5$ one).

They'll show 0 (or close to 0) Ohms for a short, and OL (for overload) or another similar symbol for an open circuit.

Same here, from my Fluke to the one I got from HF.