Why would I need 6-3 cable?

[katit]

In garage I already have sub-panel. I need to run 3 220 runs. One for mini-split, one for my air compressor and one for future lathe. From what I understand they all require just hots, no need for neutral wire.

Any practical reason why I will spend extra for 6-3?

 

[The Cobbler]

my lathe is 120/240 so I need a neutral.I think the switching is 120 volts .
what about lighting? wall outlets etc?
having 120/240 in a shop is paramount in my opinion

 

[sparky 1971]

You probably don't need 6/2 or 6/3. Wire size is based on amperage, not voltage, and I don't care, but you're gonna get beat up over 220/240. The mini split will probably need 12/2, some only need 14/2. What is the horse power of the compressor? What about the lathe? I've only wired two lathes in home garages, both of those needed a 12/2 but I've also wired a lathe that needed 60 amps of 480 volt three phase. power.

 

[katit]

MrCool 36k says 8ga and 6ga preferred - its like 40ft run so 6/2 it is. Compressor definitely needs 6/2.

Lathe - I don’t know yet which one it will be… I didn’t know they can be 120/240

I was going to buy cable in bulk from amazon so same size it is..

 

[Dig Doug]

Well you need to know what each circuit / device uses for power & what is powering your sub panel. Is your sub panel a 100 amp 3 phase panel?

I’m not an Electrician

here in Ca
to the best of my knowledge…

Typical residential electrical grid doesn’t have 3 phase power
commercial / Industrial business parks have 3 phase

is this a trick thread?
it’s so mis leading….

I don’t mean to make fun of your situation but it’s so vague in detail

every UL listed Device will have a plate / sticker on the motor and it states what ever power is required to power up that device, sometimes you get various voltage and amps in commercial applications

I have worked for .. say a Chinese businesses and they purchase machines from China for cheap ( they magically appear in a 40 ft shipping container) these can be difficult when the fire department come in for a yearly inspection in a commercial application


make a list of what you want and plan accordingly, You need to have a solid infrastructure to power your equipment




I have patio heater that use 220 volt and 13.5 amp so 12 gauge wire
I also have a welder that uses 220 and 40 amp that I use 6 gauge wire

they are completely different power usages

Dont forget Disconnects for each device!

 

[sparky 1971]

MrCool 36k says 8ga and 6ga preferred - its like 40ft run so 6/2 it is. Compressor definitely needs 6/2.

Lathe - I don’t know yet which one it will be… I didn’t know they can be 120/240

I was going to buy cable in bulk from amazon so same size it is..

There's no way I'd use 8/2 or 6/2 for the mini split. MCA is 28 so 10/2 Romex or #12 THHN/THWN in conduit would be fine. There's no reason to give MCA then contradict it with a wire size that doesn't jive. At 40 feet, voltage drop isn't going to be an issue. The MOCP is only 35.

Are you getting a 7-1/2 HP compressor? #10 in pipe or 8/2 on a 60 amp breaker is good for 5 HP.

Can't help you on the lathe other than if it needs #6 it's a big *******.

 

[wyliesdiesels]

I highly doubt your compressor needs #6.

Whats the HP rating on the motor nameplate?

 

[katit]

Ok, it's getting clearer now.
Sounds like I need /2 wiring (fact). With one mentioning from @The Cobbler of 120/240 lathe

I am coming from "ease" and "little overbuilt" kind of standpoint. I get it, maybe MrCool will be fine with 10ga, 6ga definitely overkill, so 8 IT IS (and it says so in manual)

My compressor is Quincy QT-5, so according to specs it is probably OK with 10Ga, but 8 will work for sure.

Sounds like I will be fine with 8/2 runs for both.

For lathe my "dream" right now is this: https://www.precisionmatthews.com/shop/pm-1340gt/
But if not - will be something in similar size range or little smaller. They say 20A recommended. Little overkill won't hurt.
If, for some reason I will need 120 as well, will it work if I simply have 20A 120 outlet next to it? Because I will have plenty of those going around..

At this point I am OK with going little overboard to make sure I don't have to worry about it later (if I want to go 7.5HP compressor for example)

 

[wyliesdiesels]

Umm if you want ability to run a 7.5hp motor then you need 50a rated wire. #8 NM-b is not large enough. You could go with #8 THWN in conduit though…

 

[dcg9381]

In garage I already have sub-panel.
Any practical reason why I will spend extra for 6-3?

Depends on the size of your garage and the location of the sub-panel.
I find it very useful to have sub-panels fed by 50A on BOTH sizes of the garage.

 

[katit]

Depends on the size of your garage and the location of the sub-panel.
I find it very useful to have sub-panels fed by 50A on BOTH sizes of the garage.

garage roughly 35x35 and I have 100A sub panel on one side.. Most activity where I might need something will be closer to where panel is.

 

[katit]

Umm if you want ability to run a 7.5hp motor then you need 50a rated wire. #8 NM-b is not large enough. You could go with #8 THWN in conduit though…

But I can do #6NM-b? I think it would be cheaper vs running inside conduit?

 

[dcg9381]

garage roughly 35x35 and I have 100A sub panel on one side.. Most activity where I might need something will be closer to where panel is.

I can't define your use cases for you, but for my friends, when I'm helping them build shops of 1k sqft or more, I design electrical with one sub panel on both sides... Does that cut costs? Depends on the application, but sure makes things easier.

 

[dave*99]

If, for some reason I will need 120 as well, will it work if I simply have 20A 120 outlet next to it? Because I will have plenty of those going around..

Nope.

 

[mike93lx]

But I can do #6NM-b? I think it would be cheaper vs running inside conduit?

Yes. You use the 60 degree column for NM wire.

Just has to be protected from damage

 

[katit]

Yes. You use the 60 degree column for NM wire.

Just has to be protected from damage

Can you explain what 60 degree column is?

Why can't I just run it along studs? I did it before and it passed inspection just fine.
This is behind drywall BTW

 

[sparky 1971]

Can you explain what 60 degree column is?

Why can't I just run it along studs? I did it before and it passed inspection just fine.
This is behind drywall BTW

Wire is rated for 60, 75, and 90°. The ampacity of romex is based on the 60° column of 310.16. #6 is 55 amps.

Wire Current Ampacities NEC Table 310-16

 

[mike93lx]

Why can't I just run it along studs? I did it before and it passed inspection just fine.
This is behind drywall BTW

Behind drywall is protected from damage

 

[wyliesdiesels]

Can you explain what 60 degree column is?

Why can't I just run it along studs? I did it before and it passed inspection just fine.
This is behind drywall BTW

60° column is referring to an ampacity table in the nec not a column in your building

BTW the compressor will need to be hardwired

 

[katit]

60° column is referring to an ampacity table in the nec not a column in your building

BTW the compressor will need to be hardwired

Why? Can't I just use 50A rated plug/outlet/whip?

 

[mike93lx]

Why? Can't I just use 50A rated plug/outlet/whip?

No. Needs to be rated for the HP and getting that in a plug is prohibitively expensive. An inexpensive ac disconnect will do it. They're Commonly available up to 10hp

 

[75gmck25]

I don't think this applies to HVAC or tools in the garage, but I've been told that some kitchen appliances need 6/3 (or **/3) because they run on 240 volts, but have an electric timer or controller that still uses 120 volts.

 

[Norcal]

I don't think this applies to HVAC or tools in the garage, but I've been told that some kitchen appliances need 6/3 (or **/3) because they run on 240 volts, but have an electric timer or controller that still uses 120 volts.

Ranges, dryers, ovens, require a neutral, cooktops may or may not,

 

[exranger06]

Well you need to know what each circuit / device uses for power & what is powering your sub panel. Is your sub panel a 100 amp 3 phase panel?

I’m not an Electrician

here in Ca
to the best of my knowledge…

Typical residential electrical grid doesn’t have 3 phase power
commercial / Industrial business parks have 3 phase

is this a trick thread?
it’s so mis leading….

I don’t mean to make fun of your situation but it’s so vague in detail

every UL listed Device will have a plate / sticker on the motor and it states what ever power is required to power up that device, sometimes you get various voltage and amps in commercial applications

I have worked for .. say a Chinese businesses and they purchase machines from China for cheap ( they magically appear in a 40 ft shipping container) these can be difficult when the fire department come in for a yearly inspection in a commercial application


make a list of what you want and plan accordingly, You need to have a solid infrastructure to power your equipment




I have patio heater that use 220 volt and 13.5 amp so 12 gauge wire
I also have a welder that uses 220 and 40 amp that I use 6 gauge wire

they are completely different power usages

Dont forget Disconnects for each device!

3 conductor cable has nothing to do with 3 phase vs single phase. Single phase circuits use 3 conductor cable all the time. Any appliance that uses both 240V and 120V will need 3 conductors (2 hot legs for 240V, and a neutral for 120V). Electric stoves and clothes dryers run off both 240V and 120V and need 3 conductors, for example. And even if an appliance says how many amps it uses, it's not going to explicitly tell you which size/gauge wire to run to it.

 

[exranger06]

I don't think this applies to HVAC or tools in the garage, but I've been told that some kitchen appliances need 6/3 (or **/3) because they run on 240 volts, but have an electric timer or controller that still uses 120 volts.

This is correct. Neutral wires are only for 120V circuits. Anything that runs on 240V ONLY, like an air compressor motor, doesn't need or use a neutral. Just run 2 hot legs and a ground. Only appliances like a stove or a clothes dryer that need both 240V AND 120V need a neutral to run the 120V components, in addition to the 2 hot legs.

 

[Dig Doug]

3 conductor cable has nothing to do with 3 phase vs single phase. Single phase circuits use 3 conductor cable all the time. Any appliance that uses both 240V and 120V will need 3 conductors (2 hot legs for 240V, and a neutral for 120V). Electric stoves and clothes dryers run off both 240V and 120V and need 3 conductors, for example. And even if an appliance says how many amps it uses, it's not going to explicitly tell you which size/gauge wire to run to it.

I thought ….

Romex 12-2 white black ground
romex 12-3 white black red ground

6-3 cabe is a 4 wire cable- has 4 wires
6-2 cable is a 3 wire - has 3 wires

in a residential application what would the 4 th wire be used for useing 6-3 cable ?

I just wired my cook top in a kitchen remodel - red black green - 6-2 cable/wire

 

[dave*99]

in a residential application what would the 4 th wire be used for useing 6-3 cable ?

I just wired my cook top in a kitchen remodel - red black green - 6-2 cable/wire

I wired a hot tub that needed 6-3 WG
And a sub panel that needed 6-3 WG
And a generator inlet that needed 6-3 WG

 

[wyliesdiesels]

I thought ….

Romex 12-2 white black ground
romex 12-3 white black red ground

6-3 cabe is a 4 wire cable- has 4 wires
6-2 cable is a 3 wire - has 3 wires

in a residential application what would the 4 th wire be used for useing 6-3 cable ?

I just wired my cook top in a kitchen remodel - red black green - 6-2 cable/wire

If that cooktop or range needs 120v then you need the 4th wire (white neutral) as you cannot use the EGC/ground as a grounded/neutral conductor.

Some cooktops only need 240v. However if your cooktop had a 4-wire whip or terminal block then you shouldve used 6/3 NM-b

 

[exranger06]

I thought ….

Romex 12-2 white black ground
romex 12-3 white black red ground

6-3 cabe is a 4 wire cable- has 4 wires
6-2 cable is a 3 wire - has 3 wires

in a residential application what would the 4 th wire be used for useing 6-3 cable ?

I just wired my cook top in a kitchen remodel - red black green - 6-2 cable/wire

A 6-3 cable has the same wires as a 12-3 cable: black, red, white, and bare ground. The black and red wires are the 2 hot legs, white is the neutral, and the bare ground is of course, ground. A cooktop (not a range oven) runs only on 240V, and doesn't need a neutral. Neutral wires are used ONLY for 120V. A range oven is mainly 240V, however there are components that run on 120V (the light bulb inside the oven, for example, runs on 120V). The neutral wire is there to power the 120V components.