How did you manage this? 8 AWG AC input/output for 3kw growatt inverter.

[edm]

I'm trying to do this thing, correctly.

I have a 3000w 48 v growatt inverter, and just wanted to charge my new battery bank incase power goes out. ( it'll be below freezing for 7 days straight)
I read in manual to use 8 AWG for ac lines.

I noticed my limp extension cord and guessed it was like 16 guage.
so I went to Ace and bought the 8/3 wire. I bought the female plug and I thought the bright yellow one was 30 Amp, but damn my eyesight it is 20amp. I see no listing for 40amp plugs male nor female anywhere.

I tried to wire it up but it's like wrestling an alligator.
How in the world am I suppose to do this?

I've noticed people, (internet people) cutting extension cords in 2 to use as the AC input & output on their inverters. .
Are they high?

I can't afford this mistake, I can't do anything, I'm bloody, bruised, despondent, and apparently stupid.


What gives? I can't afford breaker boxes, and further I can't decode the union electrician answers on these forums.

 

[Rednecktek]

so I went to Ace and bought the 8/3 wire. I bought the female plug and I thought the bright yellow one was 30 Amp, but damn my eyesight it is 20amp. I see no listing for 40amp plugs male nor female anywhere.

I'm guessing you're trying to connect the Growatt to a generator so you can use the generator as "utility power" to let the Growatt top up the batteries? If I'm wrong, please ignore most of this.

Yeah, there's nowhere in the NEC that allows you to put 30a through a household plug. The maximum you can do through a standard plug is 20a with 12AWG wire. What you'll need to do for a 30a is get a 30a RV plug for the end. The 8AWG for the Growatt is intended for the AC Output since it can surge up over 30a which is the limit of 10AWG, so a little extra capacity to be safe. At least that's how it's done according to code.

Now, since very few generators have a handy 30a RV plug on them to feed this, you've usually only got the bog standard 120v plugs. If you DO have a weird 3-pin round plug on there, go find the bit for that. There are a couple different "Standards" for that plug so take pictures!

Here's the kicker. In the Growatt's settings it has an entry for "maximum charging amps from utility", IIRC it's 40a for the 3000 model. That's 40a at 48v which is only 1920w of charging, which from 120v AC is only 16a. You can use the yellow 20a plug and some 12/2 wire and still be within tolerances for charging the batteries.

Yes, 8AWG is good for getting the 30a of AC power out to your 120v bus, but the "Utility Charging Max Amps" will be the number to work with for feeding from a generator or car inverter or whatever source you're working with. Making a cord with 10AWG was a real PITA for me on those same heads, I couldn't imagine doing it with 8AWG and getting anything to cram in there.

Tl;Dr: You'll never get 8AWG into a 20a plug head worth a spit, but you probably don't need to.

 

[Tecnodave]

It is perfectly acceptable to use oversized plugs and sockets, The one that comes to mind is the NEMA 14-50 connector used for electric stoves. It is rated for 50 amps non-continous duty (under 3 hours at max amps) and 40 amps continous duty. Proper wiring for an 120/240 volt inverter is 4 wires, L1, L2, N, & G both in and out

Also please note........A inverter (or for that matter, any device that can operate for more than 3 hours) must have all the feed wires , connectors, fuses, and breakers derated to 80% of maximum ampacity for “continous duty”.

For example your 20 amp 240 volt water heater must be wired with 10 guage wire (30 amps) and use a 25 amp breaker.

This is very clearly outlined in the NEC.........SEE ‘ continuous duty devices” in the code

 

[sunshine_eggo]

3000W / 120V = 25A

10awg can handle that fine.

To my knowledge, there are NO 110VAC "standard" 3 prong plugs rated for above 20A. The "standard" is 15A. 20A has one of the pins horizontal instead of vertical.

If you want to "desperation" charge your batteries with your Growatt using an extension cord plugged into a standard 15A 110V outlet, here's how:

Get an extension cord with 14awg or thicker wire.
Cut it to a suitable length.
Connect to AC input.
Configure Growatt to charge at no more than 120VAC * 15A = 1800W.
Do this by dividing 1800W by the peak generator charge voltage, e.g., 1800W / 56VDC = 32A
Set the Growatt "utility charging max amps" to 30A (give yourself some breathing room).
Plug Growatt into AC power.

Note that the Growatt has a funky AC charger. The battery must be below the start voltage, and it will only charge until the stop voltage is achived.

 

[Rednecktek]

To my knowledge, there are NO 110VAC "standard" 3 prong plugs rated for above 20A. The "standard" is 15A. 20A has one of the pins horizontal instead of vertical.

The heavy duty yellow repair plugs are often rated at 20a limit even without the horizontal post. They are regularly found at the local hardware store.

Get an extension cord with 14awg or thicker wire.

Go for a 12AWG if you can, they exist and give you some length to work with without losing too much voltage drop and pissing off the Growatt.

Note that the Growatt has a funky AC charger. The battery must be below the start voltage, and it will only charge until the stop voltage is achieved.

Isn't there a setting to change that? I seem to recall going to Utility/Solar/Batt in the priority list will start charging the batteries right away. Or is my crack habit flaring up again?

 

[edm]

Thanks for everyone's fast responses!
I did mean to imply Wall outlet input, & ac output to use as an improvised power supply for now. (Just in case)
(In future at my rural property off grid the travel trailer will have my solar panels and already has a breaker box)

I will find 12 awg cord to boot strap this.

 

[Tecnodave]

To my knowledge, there are NO 110VAC "standard" 3 prong plugs rated for above 20A. The "standard" is 15A. 20A has one of the pins horizontal instead of vertical.

NEMA standard connectors for 120 volts: 3 wire

.......................... Intermittent duty................ Continuous duty (over 3 hours).......config.

NEMA 5-15..............15 amps.....................................12 amps.........................two vertical pins
NEMA 5-20.............. 20 amps....................................16 amps............................one vertical and one horizontal
NEMA TT-30..............30 amps.....................................24 amps.............RV & Travel Trailer connector 45 degree angled connectors

 

[sunshine_eggo]

The heavy duty yellow repair plugs are often rated at 20a limit even without the horizontal post. They are regularly found at the local hardware store.


Go for a 12AWG if you can, they exist and give you some length to work with without losing too much voltage drop and pissing off the Growatt.


Isn't there a setting to change that? I seem to recall going to Utility/Solar/Batt in the priority list will start charging the batteries right away. Or is my crack habit flaring up again?

You can change the priorities, and you can change the charger start/stop voltages. Not sure about your crack habit.

You can't make it behave like the typical inverter charger where the charger will bulk/absorp/float.

 

[Tecnodave]

The heavy duty yellow repair plugs are often rated at 20a limit even without the horizontal post. They are regularly found at the local hardware store.

It is absolutely not legal to sell a NEMA 5-15 connector (two vertical prongs) rated for 20 amps in the USA,

don't know about third world countries

These do need to be “listed to UL (approiate standard) by a US OSHA NRTL”

 

[Rednecktek]

don't know about third world countries

Hey now, I may be in the sticks, but we're not 3rd world quite yet... maybe 2-1/2 world.

I know I've run across a few in my years that said NEMA-15 on the sticker, but once you opened them up on the inside there was a little stamp saying 20a MAX. Not technically legal, but selling 300w panels at 20v and 5a isn't technically legal either.

Either way, yes, the dual vertical plugs are technically limited at 15a, there's 20a outlets with the cross bar hole, but I can't say I've ever seen the sideways 20a plug more than once or twice in my life in person. The funny (annoying) thing is when people put the 20a plugs on a 15a (or less) circuit and hope nobody notices. Ggggrrrrr....

You can't make it behave like the typical inverter charger where the charger will bulk/absorp/float.

You can't? Isn't that what it's supposed to do if it has grid power but no solar coming in? It had 1 job! 3 jobs!!

 

[Rednecktek]

@edm : So is this system some sort of "solar generator" type setup or is it hard wired into a house or something? It almost sounds like this is the power system to a trailer? If this is a trailer and you're wanting to charge it up at home then there are many ways you can do this.

1: As mentioned, a 12AWG cord and a wall socket will work if you change the settings to not draw too much to trip the breaker. Pretty universal.

2: Do you already have a shore power connector? If not, take that 8AWG and make one with a standard RV plug on it. You can get RV to NEMA-15 wall outlet adapters at Ace usually for a few bucks which will give you options like wiring in a 30a outlet at the house or taking it to a camp site that has the normal RV 30a utility power or adapt it down and plug it into a generator. Lots of things you can do, you just need to think about what you'd like to do and then we can help figure out the best way to do it. Since you've already paid for the 8AWG wire, you might as well keep it around for future use.

 

[sunshine_eggo]

You can't? Isn't that what it's supposed to do if it has grid power but no solar coming in? It had 1 job! 3 jobs!!

There's a difference between supplying grid power to the loads (which it can do based on priority settings) and charging batteries. This is a peculiarity of the Growatts.

Best Price 24V Growatt SPF 3000TL LVM – 3kW 120Vac Stackable Inverter 2kW MPPT Charge Controller Split Phase 120V/240V capable with two or more units – Special – Watts247 Wholesale

watts247.com

Utility/Generator Charger tips:
The generator charger is a different beast to the solar charger. (Does not utilize the Bulk and Float Charge settings)
It works on a float valve type principle. (triggers when battery voltage drops below that on setting 12 – set the voltage higher than current battery voltage to start charging right away)
Stops charging from Generator when setting 13′ s voltage is reached
Will not start charging the battery again until it drops below battery voltage – in setting 12.
Setting 01 set to SBU to activate setting 12 and 13.
Setting 02, is the Max charging current from Solar + Utility/Generator
Setting 11, is the Maximum Generator/Utility charging current @ your battery voltage (not at 120V)
Setting 14, make sure this setting includes the option to charge from utility/generator (see manual)
Note, setting Setting 11 too high for your generator may cause your generator to falter at startup, and cause the Inverter Charger to lose synchronization with the Generator (58 to 63Hz), if in doubt start small, and work your way up.

 

[Tecnodave]

Hey now, I may be in the sticks, but we're not 3rd world quite yet... maybe 2-1/2 world.

I was born in ToAK......not exactly 1st world what? where? Aleyska

 

[Rednecktek]

I was born in ToAK......not exactly 1st world what? where? Aleyska

My mailing address is in Monroe, WA but my camp is in Ione, WA if you want to google that place.

Most of the year I'm somewhere between South Korea, Japan, Guam, Saipan, UAE, Bahrain or Kuwait.

@sunshine_eggo : I'm going to have to spend a lot of time re-reading and double checking my settings before I put my Growatt into service it looks like. It sounds like it'll only do the Buck & Float that my FLA's will want when I have enough solar to provide that instead of letting the generator do all the work AND top up the batteries when it's cloudy & miserable out. Don't be surprised if I post all my settings for review before I take it up to the camp in July when I'm shoreside again.

 

[12VoltInstalls]

If you haven’t solved the cord yet this can be wired in with a 8awg soo cord and you can get the generator end as well.
Most smallish mediumish generators these days offer an “RV Ready” version that has the 30A twist-lock three wire receptacle.

If you don’t have to have 8awg this one will do 30A for generator to that plug-in. If it were me I’d use that cord but definitely use 8ga from the in-socket to the all-in-one

 

[Tecnodave]

If you haven’t solved the cord yet this can be wired in with a 8awg soo cord and you can get the generator end as well.
Most smallish mediumish generators these days offer an “RV Ready” version that has the 30A twist-lock three wire receptacle.

If you don’t have to have 8awg this one will do 30A for generator to that plug-in. If it were me I’d use that cord but definitely use 8ga from the in-socket to the all-in-one

Exactly which RV uses an L5-30P plug.....

NONE........RV’s use a TT-30P plug on the cord.......

NEVER.......seen an RV that uses a L5-30P plug on cord

SOME..........small generators use the L5-30R outlet

Correct cord..........L5-30P plug to generator with TT-30R receptacle for RV to plug into

The cord that you specify has the wrong connector on each end

Nice try, but no cigar..

 

[Rednecktek]

NEVER.......seen an RV that uses a L5-30P plug on cord

Eeehhh, I can think of 3 off the top of my head that use that plug. Granted 2 were re-builds and 1 was a custom built trailer, but it was because their generators HAD the L5-30 and none of those campers had ever seen a park with a plug.

Considering it sounds like he's got a semi-custom rig, if he has no cord at all he can really go either way, to fit a generator and adapt to the RV style, or fit the RV style and adapt to the generator. It really depends on where he's getting his shore power from most often. Living next to the garage at home? Go for the RV style and socket from the breaker panel. Only ever using a generator? Wire up the generator head.

The wonderful thing about "Standards" is that there are SO many to choose from.

 

[Tecnodave]

I was referring to a RV that you buy from an RV dealer....not something that was fashioned into an RV.....or rebuilt into an RV

Did you go to the Amazon Ad......wrong connector on both ends.....

Please note that I am commercially licensed, I cannot recommend anything which is not clearly spelled out in the NEC... legal liability.... if you are not licensed....well I didn't know will get you by.....not so If you do have that liscense.

My Insurance and bond holder would drop me like a hot potato if I do not toe the code, not just one, all of them

 

[Ampster]

I see no listing for 40amp plugs male nor female anywhere.

There are plugs like a 14-50 which can do 50 Amps but you should be wiring through a breaker to your electrical panel not through a plug.

 

[Rednecktek]

Did you go to the Amazon Ad......wrong connector on both ends.....

Yeah, I noticed that too. I'm really interested to hear more detail about what he's got and what he's trying to do. Pics would be cool too because I've got soooo many questions about what he's trying to accomplish.

Please note that I am commercially licensed,

Really.... have I got a couple of code questions for you!