More backup generator discussion: Backing up well pump in a different structure

[rbstern]

How about a simple automatic transfer switch that only feeds the well? Normal power comes from the old house and when the power goes out the transfer switch switches to a circuit off the generator.
You won’t need any of the gen start features in the transfer switch as that will be handles by the “main” transfer switch.
I’ve never done this nor have I studied code enough to see if an isolated circuit can be fed by a separate service entrance. But if that’s truly code this would be a work around that I assume would meet code.
If code isn’t an issue (and I don’t think it is) I’ll stand by my first thought in one of the first posts in the thread.

I think, from what I've read and what grsthegreat posted above, that's a code (and/or utility co.) prohibited approach. Even isolated with a dedicated ATS, the generator is effectively providing backup power to two separately metered services. That's why a number of people have suggested the pump has to be completely isolated from the existing house circuitry, so utility or backup power for the pump only comes from one metered service.

 

[CobyRupert]

I think, from what I've read and what grsthegreat posted above, that's a code (and/or utility co.) prohibited approach. Even isolated with a dedicated ATS, the generator is effectively providing backup power to two separately metered services. That's why a number of people have suggested the pump has to be completely isolated from the existing house circuitry, so utility or backup power for the pump only comes from one metered service.

The pump can be completely isolated from the existing house utility circuitry (including the neutral) by a transfer switch at the old house. All this means is that the transfer switch has to be 3 pole (2-hots & N) instead of just 2 pole (2- hots).

A slicker way is running a circuit from the new house panel to the old house transfer switch. This way, in the rare case that new house still has utility power but old house doesn't, pump still runs and genny is not needed; but if new house loses power, then new house panel still gets energized by genny and power still goes to pump.

 

[RNeumann]

I think, from what I've read and what grsthegreat posted above, that's a code (and/or utility co.) prohibited approach. Even isolated with a dedicated ATS, the generator is effectively providing backup power to two separately metered services. That's why a number of people have suggested the pump has to be completely isolated from the existing house circuitry, so utility or backup power for the pump only comes from one metered service.

Now I’m confused. Are some saying a Backup Gen can’t power more than one metered service? If your barn and house have two meters they can’t share a gen?

It sounds like you are thinking of doing what I recommended in my first post? Now I’m curious and going to have to dive into the code books. I don’t see that as an issue but will need to verify.

 

[rbstern]

According to your diagram, they are in parallel as long as there are no check valves or closed valves that would isolate the water system normally. Your bladder tank in the old house will function in conjunction with the one in your new house.

Pump up you water pressure and turn the pump off. Open a faucet in the old house and you can run down the pressure to both houses. Do it again but this time open a faucet in the new house. Same result in a parallel system. It's no different than doing the same thing in a single house using two different faucets in separate tests.

There won't be a bladder tank in the new house. The new house is treated as a fixture off the existing tank.

As to the well specs, If you should have only a 1/2 hp pump, you're only using a fraction of the wire size capacity. Voltage drop wouldn't be large in this instance. A 2 hp pump would be a different story. If you need to stay with a 30 amp circuit, check some online voltage calculators and find what wire size is acceptable for a 30A 450 foot run.

One example:

Voltage Drop Calculator

Thanks for the link. I need to get the pump specs on my next visit to the property.

 

[Jcoon]

Distracting from OP once again, but : You may be to Code under a (IMHO) rarely used exception.
The 2017 Code (Article 250.35) allows an exception: No ground conductor is required from main panel, and bonding of ground/neutral at sub panels is allowed if "there are no continuous metallic paths..." between the buildings that connected their ground systems. Essentially they allow you not to have a ground conductor (or thinking of it another way, you can use the neutral conductor for a ground fault conductor back to the transformer) if there's no way normal neutral current can use a parallel continuous metallic "ground" path.

I assume you don't use metal conduits to sub panels?
While this exception is allowed, the problem of using this comes if a future metallic connection (water, gas pipes, duct work, etc..) is installed after the inspector leaves, or years down the road and normal neutral current uses it as a path.

Yes that is the reason I知 allowed, no metallic anywhere between any buildings and never will be.

 

[rbstern]

Now I’m confused. Are some saying a Backup Gen can’t power more than one metered service? If your barn and house have two meters they can’t share a gen?

That's what grsthegreat posted, and he seems to have hands-on experience in the same scenario. I've found similar statements from others during my research.

It sounds like you are thinking of doing what I recommended in my first post? Now I’m curious and going to have to dive into the code books. I don’t see that as an issue but will need to verify.

Yep. Basically what Jcoon proposed in post #3.

 

[fried1765]

I like redundicy, I have 2 HVAC system on a house that only needs one. I have 3 generators, 2 freezers, ect.

If I were in this situation, I would install another well for the new house and run a pipe between the houses with necessary valves to feed both houses from either well in the event of a failure.

I would keep them independent and only tie together in an emergency.

Around here, a 4" well with pump and 80 gal tank is around $4500.
Not unreasonable if you are building a new house.

I do understand that wells can be considerably higher depending on geographic location. And this option may not be feasible for everyone.

It would definitely solve your backup power issue though!

Depending on well depth/drilling conditions, a well can cost up to $30/ft.
Drilling a second well @$30/ft. (mine was 337') would cost over $10,000 just for the hole.
Then add pump, drop pipe, wire, trenching, misc, and labor, that 2nd well could cost $13,000.
That option would certainly not work for me.

 

[grsthegreat]

Why four wires? If the well pump is isolated as a single branch circuit from the new house, wouldn't it just be the two hot 120v legs and ground?

not if there is a heater or lights in the well house. most well house panels ive seen have 120 circuits there also. if they are not [present, then yes only 3 wires would be needed.

 

[grsthegreat]

Now I’m confused. Are some saying a Backup Gen can’t power more than one metered service? If your barn and house have two meters they can’t share a gen?

It sounds like you are thinking of doing what I recommended in my first post? Now I’m curious and going to have to dive into the code books. I don’t see that as an issue but will need to verify.

i have never seen an installation allowing 2 different structures, each having their own meter, to share a generator. this would mean both houses are going to also share a neutral seeing as residential transfer switches do not switch the neutral. i once asked an inspector about doing just this scenario and he adamantly stated no way. if there was a way to isolate the neutrals, then that would be a different story. you can have multiple transfer switches fed off of a single generator, but all have to be on same system.

one other thing to consider, the 150 foot run between generator and original house. the voltage drop needed to carry the generators load will need pretty large wires. then you have to consider the fact that the NEC requires that an automatic standby generator that automatically switches over to a whole house switch be capable of supplying the load without shutting down. now youve just added 2 houses to the load calcs. good luck getting the largest air cooled genny (96 amps at 240 v) to power 2 houses and meet code. if you have to switch to liquid cooled or diesel, $$$$$$

 

[dragoneggs]

Also a little off topic, curious to why are you burying your propane tank? Seems just to add cost and a bigger headache for maintenance. Is there no place to hide out of the way above ground?