Using 110v romex wiring with 24v DC system; connecting inverter to electrical panel

[DPCabin]

I wired my entire cabin (~1200 sq. ft) for 110v 20 years ago thinking I'd connect to the grid some day. But, now I'd rather not. Until I put in a whole house solar system, I'm setting up a small system (400 ah 24V batteries & 600w solar panels). My reason for choosing to go with 24v is that I'd like to use some of the circuits already in place connected with 12 AWG romex wire. Some circuits would be DC and some AC via an inverter. All I plan to run on DC are LED lights, a few DC ceiling fans, maybe a few more things as I figure out the system and learn more about limits.

First question: Is this a reasonable approach? Any problem with using existing romex wiring for DC circuits with DC fixtures? I'm doing it now on a small scale with 12v and have had no problems (breakers tripping).

Second question: Is it possible to run a wire directly from the inverter (e.g. the 2000 watt sin inverter Will mentions on his website for a 24v off-grid system) to the AC breaker box/panel? I am confused by the inverters having 3 pronged plugs which are not very applicable to circuits. Should I just cut a 3 pronged extension cord of an appropriate gauge and wire it to the AC panel on one end and plug it into the inverter? Or, are there connections to direct wire the inverter to AC circuits? I don't have the inverter in hand yet.

Thanks.

 

[Bob142]

Second question: Is it possible to run a wire directly from the inverter (e.g. the 2000 watt sin inverter Will mentions on his website for a 24v off-grid system) to the AC breaker box/panel? I am confused by the inverters having 3 pronged plugs which are not very applicable to circuits. Should I just cut a 3 pronged extension cord of an appropriate gauge and wire it to the AC panel on one end and plug it into the inverter? Or, are there connections to direct wire the inverter to AC circuits? I don't have the inverter in hand yet.

I suggest you find an inverter (or inverter/charger) that you can hard wire. There are a lot of manufacturers and models out there for that use case.
Just some examples. Not intended to steer you towards a product, just giving you a flavor of what you can find out there.

This 24V Samlex inverter that has both outlets AND can be hardwired:

3000 Watt 24V Power Inverter | PST-3000-24 | Samlex America

Industrial Grade 3000W 24V DC-AC Pure Sine Wave Power Inverter. Converts 24VDC to 120VAC. Robust, heavy-duty power for tools, appliances and electronics.

www.samlexamerica.com

This 24V Samlex inverter/charger is for hardwiring:

2200 Watt 24V Pure Sine Inverter/Charger | EVO-2224 | Samlex America

2000W 24V Pure Sine Wave Inverter/Charger with 70A Battery Charger + 40A Transfer Switch. Marine grade, heavy-duty power for rv, boat & off-grid. Lithium compatible.

www.samlexamerica.com

Guys like @Steve_S and @JeepHammer (and others) have a ton of experience living off-grid. You may want to reach out to them directly to get advice on the best way to leverage what you already have.

 

[JeepHammer]

Respectfully,
I went the AC/DC in the home route, and unless you just have a crap ton of DC powered stuff, it doesn't make a lot of sense to dual wire the entire house.
I'm glad I figured that out before we built the house...

You CAN go with a 240 Vac inverter, use a common breaker box and be just like everyone else.
I did just that. Your 120 Vac wiring will simply plug into a 240 Vac breaker box like everyone else, and the 240 Vac inverter will power that.
The breaker panel doesn't care where the 'Source' comes from as long as it's 240 Vac (or there about).

With any whole house system, it's more efficient to use a 240 vac inverter, simply because you are like anyone else, you can use all the 120 Vac hardware that plentiful and inexpensive, and 240 Vac inverters run more efficiently.

*IF* you run a split/dual system, DO NOT use common 120 Vac receptacles, use a DC rated receptacles.
It's a different plug arrangement, you can't mix the two up.

*IF* your existing inverter is 120 vac, you can use a 'Side Panel' breaker box for that 120 Vac power and wire your 120 Vac side just like everyone else.
Keep in mind the common small inverters have about 15 Amp 'Plug In' circuits, so you will be limited to about 15 Amps on any feed to a breaker panel.

AC wiring is a little different, It will have one 'Line' (Hot) wire, usually black, One 'Neutral' wire, usually white, and one 'Earth Ground' wire, usually bare or green.

The 'Earth Ground' is exactly what it sounds like, it's a copper plated metal rod driven into the earth, and if you want your AC work to be safe, you MUST do this. This is the last ditch, fail safe for AC power that will seek Earth Ground above all else, keeping YOU from getting zapped.





Common outlets will have a 'Gold' or Brass colored terminal, and that is ALWAYS the 'Line', 'Hot' or 'Black' connection.
They will have a silver colored terminal, that is ALWAYS 'Neutral' or white wire connection.
The Green terminal is the bare or green wire connection.

If you notice the top drawing, the entire metal frame, and the center screw hole are all 'Earth Grounded', anything in green is earth ground.

Does this help at all?

 

[SolarRat]

First question: Is this a reasonable approach? Any problem with using existing romex wiring for DC circuits with DC fixtures?

It shouldn't be a problem at all, just make sure all connection points are vibration-proof.

 

[offgriddle]

Respectfully,
I went the AC/DC in the home route, and unless you just have a crap ton of DC powered stuff, it doesn't make a lot of sense to dual wire the entire house.
I'm glad I figured that out before we built the house...

You CAN go with a 240 Vac inverter, use a common breaker box and be just like everyone else.
I did just that. Your 120 Vac wiring will simply plug into a 240 Vac breaker box like everyone else, and the 240 Vac inverter will power that.
The breaker panel doesn't care where the 'Source' comes from as long as it's 240 Vac (or there about).

With any whole house system, it's more efficient to use a 240 vac inverter, simply because you are like anyone else, you can use all the 120 Vac hardware that plentiful and inexpensive, and 240 Vac inverters run more efficiently.

*IF* you run a split/dual system, DO NOT use common 120 Vac receptacles, use a DC rated receptacles.
It's a different plug arrangement, you can't mix the two up.

*IF* your existing inverter is 120 vac, you can use a 'Side Panel' breaker box for that 120 Vac power and wire your 120 Vac side just like everyone else.
Keep in mind the common small inverters have about 15 Amp 'Plug In' circuits, so you will be limited to about 15 Amps on any feed to a breaker panel.

AC wiring is a little different, It will have one 'Line' (Hot) wire, usually black, One 'Neutral' wire, usually white, and one 'Earth Ground' wire, usually bare or green.

The 'Earth Ground' is exactly what it sounds like, it's a copper plated metal rod driven into the earth, and if you want your AC work to be safe, you MUST do this. This is the last ditch, fail safe for AC power that will seek Earth Ground above all else, keeping YOU from getting zapped.

View attachment 5130

View attachment 5131

Common outlets will have a 'Gold' or Brass colored terminal, and that is ALWAYS the 'Line', 'Hot' or 'Black' connection.
They will have a silver colored terminal, that is ALWAYS 'Neutral' or white wire connection.
The Green terminal is the bare or green wire connection.

If you notice the top drawing, the entire metal frame, and the center screw hole are all 'Earth Grounded', anything in green is earth ground.

Does this help at all?

Really nice write up thank you. My cabin is now wired with 12 ga copper intended for AC power, but of course would pass DC really well too After I purchase or build a series compatible lifepo battery bank, I will then get a 24vdc in, 220vac out invertor and wire it into the main breaker of my standard, household, service panel just as if it was coming from the grid. If I want to operate any 12vdc stuff, I will feed a 24 to12 vdc invertor via my battery bank and sent the DC voltage to clearly seperate and we'll defined locations in the tajmahcabin.

 

[John Frum]

Really nice write up thank you. My cabin is now wired with 12 ga copper intended for AC power, but of course would pass DC really well too After I purchase or build a series compatible lifepo battery bank, I will then get a 24vdc in, 220vac out invertor and wire it into the main breaker of my standard, household, service panel just as if it was coming from the grid. If I want to operate any 12vdc stuff, I will feed a 24 to12 vdc invertor via my battery bank and sent the DC voltage to clearly seperate and we'll defined locations in the tajmahcabin.

Keep the amperage limitations of 12 AWG solid copper and voltage drop over distance in mind and it "should"TM work

 

[Steve_S]

I'll chime in here. 100% off grid, use 120VAC only including my deep well pump (260' deep) which is a soft-start Grundfos SQ-5.
24V FLA battery bank + 1 24V/348AH LFP pack. The inverter only uses 18W on idle without powersave ON.
I have a 24V -> 12V/20A buck converter for any 12VDC stuff I may want to use in the powerhouse. It's backup power for the RV furnace warming the powerhouse.

Keeping it simple is often the best and most frugal for the wallet & power usage, over complicating can & often does cause more problems than it's worth.

 

[JAS]

My .02 regarding connecting inverter to panel...

I have a Xantrex 600W ProWatt. (No hardwire option). My panel has a 240v Generator Inlet. Initially, I just created a cord (can actually purchase them and/or adapters on Amazon) that went from my Inverter into the Panel Inlet. Basically, I'm just treating my Inverter like a portable generator.

Since then, I have installed a transfer switch in between the inlet and the Inverter and Generator such that when the Generator is started the transfer switch auto transfers to the generator and then auto switches back when the generator is shut off. I did NOT however hardwire the transfer switch into the panel. I just did the same thing and created a cord to plug into my inlet. That way if/when the transfer switch dies (It was only about $100 on Amazon), I can just bypass around it easily with either the generator or the inverter...

 

[DPCabin]

Respectfully,
I went the AC/DC in the home route, and unless you just have a crap ton of DC powered stuff, it doesn't make a lot of sense to dual wire the entire house.
I'm glad I figured that out before we built the house...

You CAN go with a 240 Vac inverter, use a common breaker box and be just like everyone else.
I did just that. Your 120 Vac wiring will simply plug into a 240 Vac breaker box like everyone else, and the 240 Vac inverter will power that.
The breaker panel doesn't care where the 'Source' comes from as long as it's 240 Vac (or there about).

With any whole house system, it's more efficient to use a 240 vac inverter, simply because you are like anyone else, you can use all the 120 Vac hardware that plentiful and inexpensive, and 240 Vac inverters run more efficiently.

*IF* you run a split/dual system, DO NOT use common 120 Vac receptacles, use a DC rated receptacles.
It's a different plug arrangement, you can't mix the two up.

*IF* your existing inverter is 120 vac, you can use a 'Side Panel' breaker box for that 120 Vac power and wire your 120 Vac side just like everyone else.
Keep in mind the common small inverters have about 15 Amp 'Plug In' circuits, so you will be limited to about 15 Amps on any feed to a breaker panel.

AC wiring is a little different, It will have one 'Line' (Hot) wire, usually black, One 'Neutral' wire, usually white, and one 'Earth Ground' wire, usually bare or green.

The 'Earth Ground' is exactly what it sounds like, it's a copper plated metal rod driven into the earth, and if you want your AC work to be safe, you MUST do this. This is the last ditch, fail safe for AC power that will seek Earth Ground above all else, keeping YOU from getting zapped.

View attachment 5130

View attachment 5131

Common outlets will have a 'Gold' or Brass colored terminal, and that is ALWAYS the 'Line', 'Hot' or 'Black' connection.
They will have a silver colored terminal, that is ALWAYS 'Neutral' or white wire connection.
The Green terminal is the bare or green wire connection.

If you notice the top drawing, the entire metal frame, and the center screw hole are all 'Earth Grounded', anything in green is earth ground.

Does this help at all?

Thanks for your reply

 

[DPCabin]

Thanks everyone for the help! The specifics of some of your comments will take a bit of pondering and research to understand completely. Two main points I'll act on are dropping the DC running through existing romex lines and looking into an inverter I can wire directly into the panel. More later I'm sure...

 

[ghostwriter66]

I wired my entire cabin (~1200 sq. ft) for 110v 20 years ago thinking I'd connect to the grid some day. But, now I'd rather not. Until I put in a whole house solar system, I'm setting up a small system (400 ah 24V batteries & 600w solar panels). My reason for choosing to go with 24v is that I'd like to use some of the circuits already in place connected with 12 AWG romex wire. Some circuits would be DC and some AC via an inverter. All I plan to run on DC are LED lights, a few DC ceiling fans, maybe a few more things as I figure out the system and learn more about limits.

First question: Is this a reasonable approach? Any problem with using existing romex wiring for DC circuits with DC fixtures? I'm doing it now on a small scale with 12v and have had no problems (breakers tripping).

Second question: Is it possible to run a wire directly from the inverter (e.g. the 2000 watt sin inverter Will mentions on his website for a 24v off-grid system) to the AC breaker box/panel? I am confused by the inverters having 3 pronged plugs which are not very applicable to circuits. Should I just cut a 3 pronged extension cord of an appropriate gauge and wire it to the AC panel on one end and plug it into the inverter? Or, are there connections to direct wire the inverter to AC circuits? I don't have the inverter in hand yet.

Thanks.

The answer to your question is YES .. you are fine ...

So working with allot of oil field guys that like to keep everything SIMPLE and will short cut everything here is what they do to power the entire trailer via batteries ...

IF your trailer has a 30A or 50A Shore power connecter get yourself a dogbone power cord plug adapter 15 amp male to 50 (or 30) amp female locking ... Like this one .. https://www.amazon.com/LeisureCords-Trailer-dogbone-connector-Indicator/dp/B077GFTQ67/ref=sr_1_5?crid=LW9U65SG7M2U&keywords=50a+to+15a+rv+adapter&qid=1579187913&sprefix=50a+to+,aps,179&sr=8-5

Plug that into the shore power outlet on your trialer ... then run an extension cord from the inverter outlet to that plug ... then turn OFF your trailer converter (should be a breaker on your panel) ... and you now have all your outlets working off your inverter AND 12V DC for your lights ...

Going a step further what some of these guys have done is actually ran a electrical cord to a socket that is mounted right below the 30/50A shore power connected ran a socket from the 30/50A shore power connector and will plug the male 15A end into that socket so they con't have to mess with a extension cord all the time ...

With that said - I'm an engineer and not an Electrician so that means that I am paper smart with no common sense -- so take everything above with a grain of salt (safety) ...

 

[offgriddle]

Keep the amperage limitations of 12 AWG solid copper and voltage drop over distance in mind and it "should"TM work

Voltage drop in wires with DC is more extreme than with AC for sure thanks. You know what I wonder about from time to time, 20 amps is the maximum current for Romex right, soooo is it the same 20amps maximum rating whether it be DC current or AC current?

 

[offgriddle]

I'll chime in here. 100% off grid, use 120VAC only including my deep well pump (260' deep) which is a soft-start Grundfos SQ-5.
24V FLA battery bank + 1 24V/348AH LFP pack. The inverter only uses 18W on idle without powersave ON.
I have a 24V -> 12V/20A buck converter for any 12VDC stuff I may want to use in the powerhouse. It's backup power for the RV furnace warming the powerhouse.

Keeping it simple is often the best and most frugal for the wallet & power usage, over complicating can & often does cause more problems than it's worth.

Way to go, off gridders are so precious and few. My well is about 260 feet deep too, I have a 1/2 hp 220 vac deep well pump. I have heard of the soft start lower voltage pumps, do you like yours?

 

[Steve_S]

Way to go, off gridders are so precious and few. My well is about 260 feet deep too, I have a 1/2 hp 220 vac deep well pump. I have heard of the soft start lower voltage pumps, do you like yours?

It great actually, you never notice a pressure change at all. when the pump kicks on, it starts at 500W and stages up to 1000W when it hits max pressure (I have it set to 47psi) . The Inverter is quite happy with this as I can watch the power usage through the inverter's display. Being on 120V and running from a 24V battery it's a great solution. BUT Grundfos is High End and as a result are NOT CHEAP and you do get what you pay for.

My well is Cable Drilled (so highly fractured as opposed to bore drilling) through banded granite and I knew I would have at least 4 years of sediment to deal with, the water is slightly hard as well, so I wanted to ensure trouble free water which made the Grundfos a no brainer. It is pushing 260' UP to a 50 Gallon pressure tank in the powerhouse, then another 75' to the cabin and going through a double filter system for sediment & fine particles (costs me 2psi pressure).

 

[offgriddle]

It great actually, you never notice a pressure change at all. when the pump kicks on, it starts at 500W and stages up to 1000W when it hits max pressure (I have it set to 47psi) . The Inverter is quite happy with this as I can watch the power usage through the inverter's display. Being on 120V and running from a 24V battery it's a great solution. BUT Grundfos is High End and as a result are NOT CHEAP and you do get what you pay for.

My well is Cable Drilled (so highly fractured as opposed to bore drilling) through banded granite and I knew I would have at least 4 years of sediment to deal with, the water is slightly hard as well, so I wanted to ensure trouble free water which made the Grundfos a no brainer. It is pushing 260' UP to a 50 Gallon pressure tank in the powerhouse, then another 75' to the cabin and going through a double filter system for sediment & fine particles (costs me 2psi pressure).

Thank you for the information, I've never heard of a cable drilled well, I can't even picture what kind of drill rig that would be! How many gpm can younr Grundfos pump? I set the pressure switch on my six gallon xtrol pressure tank to turn the pump on at 40psi, off at 60psi.

 

[Steve_S]

There are two ways to drill a well, Cable Pounder Drill or Bore Drill, bore drills use a rotation bit to cut into the rock, less fracturing of the rock so lower flows, therefore they have to go deeper to get same water flow and for reserve (makes more $ for driller as it needs typically 20% more depth). Cable Drilling is the older method of brute force pulverizing of the rock, fracturing the rock, improving flow BUT with much more sediment release over the first few years, it is also more time consuming (took 2 weeks to drill my well). I dunno the exact GPM it's consistent and attempting to empty my well is a serious challenge as I only managed to do it once in the summer but it filled quite quickly so....

WATER WELL DRILLING METHODS

https://www.michigan.gov/documents/deq/deq-wb-dwehs-gwwfwim-section5_183030_7.pdf

 

[Deleted member 783]

There are two ways to drill a well, Cable Pounder Drill or Bore Drill, bore drills use a rotation bit to cut into the rock, less fracturing of the rock so lower flows, therefore they have to go deeper to get same water flow and for reserve (makes more $ for driller as it needs typically 20% more depth). Cable Drilling is the older method of brute force pulverizing of the rock, fracturing the rock, improving flow BUT with much more sediment release over the first few years, it is also more time consuming (took 2 weeks to drill my well). I dunno the exact GPM it's consistent and attempting to empty my well is a serious challenge as I only managed to do it once in the summer but it filled quite quickly so....

WATER WELL DRILLING METHODS

https://www.michigan.gov/documents/deq/deq-wb-dwehs-gwwfwim-section5_183030_7.pdf

You can also drive a well (sandpoint) or water jet a well, if your ground water is at a reasonable depth and you dont have rocks to go through. I've successfully done both on my property, but my water is at 22'. Grundfos is the best pump on the planet, hands down. I'm guessing yours was $2,000+?

 

[Steve_S]

My Well driller supplied it at a respectable discount (< $1000) but with $12,000 hole...

 

[John Frum]

Voltage drop in wires with DC is more extreme than with AC for sure thanks. You know what I wonder about from time to time, 20 amps is the maximum current for Romex right, soooo is it the same 20amps maximum rating whether it be DC current or AC current?

I go by this chart

 

[JeepHammer]

There are two ways to drill a well, Cable Pounder Drill or Bore Drill, bore drills use a rotation bit to cut into the rock, less fracturing of the rock so lower flows, therefore they have to go deeper to get same water flow and for reserve (makes more $ for driller as it needs typically 20% more depth). Cable Drilling is the older method of brute force pulverizing of the rock, fracturing the rock, improving flow BUT with much more sediment release over the first few years, it is also more time consuming (took 2 weeks to drill my well). I dunno the exact GPM it's consistent and attempting to empty my well is a serious challenge as I only managed to do it once in the summer but it filled quite quickly so....

WATER WELL DRILLING METHODS

https://www.michigan.gov/documents/deq/deq-wb-dwehs-gwwfwim-section5_183030_7.pdf

I'm in limestone so I didn't need a hammer drill.
I did have a 10" hole/casing done so I can run a hand pump and sediment lift.
I went with stainless screen also.

The sediment lift is nothing more than two tubes dropped within a foot or so of the bottom,
One smaller than the other.
The smaller connects to the larger at a 'T' at the bottom of the larger.
I pump compressed air into the smaller, the bubbles rise drawing water/sediment in the larger, air bubbles rise and bring sediment to surface with water.

It works best if you don't let the sediment pack in around the lift tube.
It's a stupid simple idea I got from watching guys lift sediment in a commercial well.
I thought air was easier than a trash pump that lifts water & sediment, I had an air compressor but not a big water pump.