New system layout issues / q's.

[hpeyerl]

I have an existing home in the forest. I recently acquired a portable office type building with an integrated 20kW 3phase-208 diesel generator. I rewired the taps on the generator so it is now split-phase 240.

Currently we experience approximately 10-15 grid outages per year, some of them as short as a few seconds, some as long as one or two days. The generator works great except it consumes a lot of diesel. Our base load is obviously nowhere near the generator's capacity so while we're asleep, our base load is on the order of 1000-1500watts (furnace fan, computers, clocks, yard light, etc).

Also, currently, I don't have an actual transfer switch; which is bad. Before I start the generator, I have to walk to the pole, turn off the main breaker at the meter, then walk 100m to turn on the generator. I hope to fix that.

I have access to telecom batteries (that are still good but get swapped out prophylactically by the cellphone provider. My friend 'disposes' of them by giving them to me).

What I think I want to do is buy something like an LVX6048, wire the grid to "AC Input", and wire my loads to "AC Output" and connect the batteries to the built in charger.

This is where the problem comes in.

My site layout looks like this:



Because the generator is integrated into my Workshop building (and weighs 1300lbs, and is noisy), I can't really move/separate it from the workshop. Thus it is presently at the end of an underground cable that goes to the Garage which is itself at the end of an underground cable that originates at the meter on the same line as my garage/office loads. This works fine in the current scenario because if I disconnect the grid at the pole and start the generator, it powers everything, including the house.

So I have thought of a number of options, none of them ideal:

1) move the generator. Yuck.
2) dig another trench or daylight the existing trench to add a dedicated generator circuit. Yuck.
3) A second inverter for just the Garage/Workshop/Generator and a transfer switch that can switch its AC Output to the AC Input of the main inverter on demand. (yuck).

If I choose option (3), then I can run off-grid when the grid goes down, using the internal transfer switch on the LVX6048. For long outages, when my batteries get low on charge, I can turn off the main breaker at the meter base, hit the transfer switch to move that whole segment onto the AC Input, start the generator, charge the batteries, shut down the generator, move the transfer switch back, turn the main breaker back on again. This will typically happen once per year.

Note: I do have a disconnect at the generator as well so I can run the generator isolated from any power circuits, for maintenance purposes. That disconnect is usually in the disconnected position anyway.

Is there a better idea I haven't thought of?

 

[John Frum]

Where is the main(service entrance panel)?

 

[hpeyerl]

Where is the main(service entrance panel)?

I'm not sure specifically what you mean so let me describe the layout in more detail.

Overhead power from the street comes to the top of a pole in my yard where there is a transformer. A line comes down from the transformer to a meter base. In the same housing as the meter base is a 200A breaker. Below that, in the same housing is where my two underground lines terminate. One from the house, and one from the garage.

Inside the house, I have a 200A panel, and a 100A sub-panel. Technically the 200A panel is a sub because the bonding screw has been removed.

Inside the garage, I have a 100A panel also with bonding screw removed. In this panel is a 60A breaker for the line that runs to the office.

Inside the office, is a 60A panel. The generator can feed that panel and consequently the line back to the garage.

 

[John Frum]

By main(service entrance) panel, I mean the one with the neutral bonded to ground.

 

[hpeyerl]

By main(service entrance) panel, I mean the one with the neutral bonded to ground.

Ok. That's at the meter base on the pole and where my main 200A breaker is.

 

[John Frum]

Does office = garage?

 

[hpeyerl]

Office is a separate building located past the garage and is fed with its own line that comes from the garage. In the diagram it is labelled as 'Workshop' and for that confusion I apologize.

 

[John Frum]

As I see it you have 3 runs of buried cable.

1: pole to house
2: pole to garage
3: garage to workshop

What awg are each of these runs?
Are you planning to put the core of the system in the workshop?

 

[hpeyerl]

Does office = garage?

Incidentally, this is where the bonding is done, at the bottom of the meter base and housing, below the 200A breaker provided by the utilitiy.

New item by H P

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[John Frum]

Is that buried wire aluminum?

 

[hpeyerl]

As I see it you have 3 runs of buried cable.

1: pole to house
2: pole to garage
3: garage to workshop

What awg are each of these runs?
Are you planning to put the core of the system in the workshop?

1) USEB-90. (4/0? 2/0?)
2) I'm not sure the gauge. It pre-dates me.
3) AWG6

My plan is to construct an outbuilding approximately 5m from the pole and have the utility move the meter base to that small building, then trench to the pole so I can connect to (1) and (2) above. I've been speaking with the utility already but need to book them in for a site visit to discuss the details. I wanted to get the rest of my ducks in a row with this posting before doing that.

I'm in the planning/investigation stages as you can tell.

Is that wire aluminum?

Yes. I periodically ensure it is torqued.

 

[John Frum]

I think 6 awg aluminum is undersized for a 100 amp sub panel.

https://media.distributordatasolutions.com/ThomasAndBetts/v2/part2/files/File_7437_emAlbumalbumsOcal20(USA)oc_1_g_nec31016pdfClickHerea.pdf

 

[John Frum]

Anyways I was trying to figure out if you could re-purpose one on the buried wires.
I was going to suggest you build the system in proximity to the generator and make that the main panel.

 

[hpeyerl]

the 6 going to the Workshop is to a 60A panel.

 

[hpeyerl]

Anyways I was trying to figure out if you could re-purpose one on the buried wires.
I was going to suggest you build the system in proximity to the generator and make that the main panel.

well, I have 3" conduit from workshop to garage panel so I can drop some more conductors into that. But the underground line from garage to pole doesn't have conduit; it's just direct burial. So yeah, I'd love to build everything out near the garage especially since that's where my big section of south-facing roof currently is as well. and I also suppose since the system would be limited by the inverter size, I could put the inverter/batteries in the garage. However, then I have a transfer-switch problem with the 200A service to the house.

If there was such a thing as a remote transfer switch (and I could afford it if it existed) then that'd be terrific...

 

[John Frum]

If there was such a thing as a remote transfer switch (and I could afford it if it existed) then that'd be terrific...

I suspect there is.

 

[iamrich]

I haven't had enough coffee this morning to understand your goals Are you trying to power everything (Workshop, garage, house)?

 

[hpeyerl]

I haven't had enough coffee this morning to understand your goals Are you trying to power everything (Workshop, garage, house)?

Yes. Though I have enough UPSes on critical stuff that I can handle a few minutes of outage while I switch stuff over if necessary.

 

[John Frum]

The generator, utility and inverters need to be mutually exclusive.
I think what you want to do is energize the buried cable from workshop to main disconnect from either end depending on which power source is available.
I imagine that would need a switch at either end that has to have a very reliable mechanism to keep them synchronized to avoid any problems.
I've not seen that done.

Am I correct?

 

[hpeyerl]

The generator, utility and inverters need to be mutually exclusive.
I think what you want to do is energize the buried cable from workshop to main disconnect from either end depending on which power source is available.
I imagine that would need a switch at either end that has to have a very reliable mechanism to keep them synchronized to avoid any problems.
I've not seen that done.

Am I correct?

I think you're correct, yes.

One other option is to not use the LVX6048 because it doesn't have a generator input, but use something else like an Outback or Victron or other thing I don't know about that has a generator input. Then on the relatively rare occasions where I need to start the generator to charge the batteries, I can use another transfer switch to switch the garage-line over to the generator input from the load-side of the inverter.. Since that would only be on longer outages, it would be an acceptable manual process.

?

(I need to run out to get my oil changed. I'll be online later in the day).