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Underground wire grid tie recommendations & breaker

chocoheadfred

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Oct 25, 2021
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I've gotten to the point where I'm ready to connect my tiny house to the grid.

For AirBNB purposes, I think it's unique to say it's off-grid yet I think it's way more cool to ensure our guests don't run out of power.

Plus we eventually set up net metering as we are generating way more power than we can store today.

The math doesn't seem to support adding another $2k battery relative to the cost of adding grid tie, and I just sleep better at night knowing that there is backup.

So with that said, I'm looking between 4-4-4-4 direct burial vs 10/4 SJOOW. Both are about the same cost at 250' but I'm wondering what pros/cons of each are, or if you'd recommend another type of wire. The purpose is to charge the batteries if they need it, direct support of loads in the tiny house, and net metering in the future. I'd like to get away from using conduit because of cost and complexity of pulling wire that long of a distance, but will do it if needed.

Also, I'm wondering what size breaker I should get as well. I think there is a minimum voltage amount needed to charge the batteries yet don't understand pros/cons of charging them quicker/slower. I have the tiny house connected via a traditional 3 prong RV charger that I'll connect into.

Last thing is my breaker doesn't have a main disconnect. I've never installed a breaker and looks like you can do it with the power on yet best to turn it off. Any recommendations here as well? Also for the negative and ground, I'll connect them to the same bus bar, right (as shown in img_1262.jpg) as the other breakers are wired currently.
 

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Don’t put breakers in hot if there’s a way to de-energize the system.

And what’s the distance in feet, the specs of the charger amps/volts input, and have you considered the factors of integrating/isolating grid from the off-grid system to keep the bare/green safety ground properly handled?
 
Don’t put breakers in hot if there’s a way to de-energize the system.

And what’s the distance in feet, the specs of the charger amps/volts input, and have you considered the factors of integrating/isolating grid from the off-grid system to keep the bare/green safety ground properly handled?
Understood about breakers, thanks. I don't how to de-energize the system though without a main disconnect.

250' is the distance. Below are the specs of the charging amps/volts:
Growatt SPF 5000ES - Google Drive 2022-01-19 10-28-48.png
So, I think this means I need 230 volts AC @ 80 amps minimum to charge the batteries.

And no I don't what the factors are with "integrating/isolating grid from the off-grid system to keep the bare/green safety ground properly handled?" Can you help me understand these factors?
 
I've gotten to the point where I'm ready to connect my tiny house to the grid.

For AirBNB purposes, I think it's unique to say it's off-grid yet I think it's way more cool to ensure our guests don't run out of power.

Plus we eventually set up net metering as we are generating way more power than we can store today.

The math doesn't seem to support adding another $2k battery relative to the cost of adding grid tie, and I just sleep better at night knowing that there is backup.

So with that said, I'm looking between 4-4-4-4 direct burial vs 10/4 SJOOW. Both are about the same cost at 250' but I'm wondering what pros/cons of each are, or if you'd recommend another type of wire. The purpose is to charge the batteries if they need it, direct support of loads in the tiny house, and net metering in the future. I'd like to get away from using conduit because of cost and complexity of pulling wire that long of a distance, but will do it if needed.

Also, I'm wondering what size breaker I should get as well. I think there is a minimum voltage amount needed to charge the batteries yet don't understand pros/cons of charging them quicker/slower. I have the tiny house connected via a traditional 3 prong RV charger that I'll connect into.

Last thing is my breaker doesn't have a main disconnect. I've never installed a breaker and looks like you can do it with the power on yet best to turn it off. Any recommendations here as well? Also for the negative and ground, I'll connect them to the same bus bar, right (as shown in img_1262.jpg) as the other breakers are wired currently.
I may be mistaken but SJ would not be rated for direct burial and may not be rated for conduit.
 
I may be mistaken but SJ would not be rated for direct burial and may not be rated for conduit.
I did a quick Google and looks like SJ/SOOW isn't rated for direct burial so looks like that option is out. Thanks!

What wire would you recommend then for my needs?
 
I like direct burial.
The last time I looked into this was also for a campground and I recommended the same product or at least very similar from the same vendor.
 
I like direct burial.
The last time I looked into this was also for a campground and I recommended the same product or at least very similar from the same vendor.
Thanks. Did you have any issue connecting 4 gauge into your breaker? I've never worked with wiring that thick and don't know if it will fit and if so how hard it is to get in there.
 
Thanks. Did you have any issue connecting 4 gauge into your breaker?
I didn't do it, I just make suggestions on the forum to a user that needs to distribute power.
Check the breaker to see if it has mechanical lugs big enough to support the wire.
The breaker's primary job is to protect the wire so you should be able to find one to fit.
 
I don't how to de-energize the system though without a main disconnect.
There’s always a way to disconnect. Nothing should be hardwired without a breaker, ever!
So, I think this means I need 230 volts AC @ 80 amps minimum to charge the batteries.
You are in USA? I don’t think that is the droid you are looking for.

Please remind us of the inverter/charger/SCC you have.
And what country you are in.
 
So, I think this means I need 230 volts AC @ 80 amps minimum to charge the batteries.
That is 80 amps at dc charging voltage which will be ~56.8 volts.
To supply that you will need...
80 amps * 56.8 volts / .8 conversion factor = 5680 ac watts
5680 ac watts / 230VAC = 24.695652174 ac amps
 
If the panel doesn’t have a main breaker check by the meter socket sometimes they have a combo box with the disconnect located there. I also agree that there is a way to denergize your panel, you just haven’t found it yet.
 
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