Converting a 6-20P plug to fit a 14-30R receptacle.

[Brogan]

I have 240V outlets in my garage - they are 4 prong 14-30R receptacles.

I have two tools which are 220V but they have this plug which I believe is a 6-20P.

There are 3 wires - green, black, and white.

How would I correctly wire a new 14-30P to that?

Do I just not wire anything to the neutral terminal in the plug?
Does it matter which terminal the white and black are connected to - i.e. white to Y, black to X, or vice versa?

 

[Brogan]

Oh and as a follow up, where can I get some cheap(er) plugs?
HD has them but they are $20 each!

 

[Brogan]

I guess I could get one of these: https://www.homedepot.com/p/Whirlpool-4-ft-4-Wire-30-Amp-Dryer-Cord-PT400L/202647848

And connect the green/black/red to a 6-20R: https://www.homedepot.com/p/Eaton-20-Amp-250-Volt-6-20-Ultra-Grip-Connector-AH5469/206469371

Essentially a small extension cable which converts one outlet to the other.

Like this: https://smile.amazon.com/AC-WORKS-S1430620-012-4-Prong-Connector/dp/B077GLWV7J

 

[Brogan]

I found these which aren't too bad: https://smile.amazon.com/Legrand-Seymour-3867CC5-125-volt-250-volt/dp/B000BQW4OS

I can just get 2 of those, assuming I can safely wire a 3 core cable to a 4 prong plug.


P.S Ever get the feeling you're talking to yourself

 

[SteveColes]

Everyone will probably hate my recommendation. But, I with 220 in shop, I prefer l locking plug and recepticles. So I would go with L14-30x. Just my 2 cents.

 

[SteveColes]

P.S Ever get the feeling you're talking to yourself

yes especially when I am talking to ......... :gar-La;

 

[ehpoole]

If I may suggest a better route so that your wiring remains Code compliant -- you can't just replace the 14-30r receptacle with 20A rated receptacles unless you also replace the 30A circuit breaker with a 20A breaker (in which case go for it) -- either use a 14-30p plug or convert the receptacle to a 30A twist-lock receptacle and plugs (either 3 or 4-pin depending upon whether you actually need the neutral for 120V...if you do not need 120V, which is unlikely, then go 3-pin and just cap off the white neutral conductor in the outlet wiring box). This will keep your plugs and receptacles compliant as the plug receptacle and plug amperage ratings will be equal to the circuit breaker rating.

As far as what goes to what, you are interested in the X, Y (the two straight prongs) and G/E (the half round prong) prongs of your existing receptacle where X and Y are the two 120V legs, that create 240V between them, (the two "hots") and the G/E pin is the safety earth/ground pin. The ground should be a green wire (or yellow and green if European wiring) and the two hots (X and Y) may be red, black, or blue (or brown, blue or black of European) in your existing outlet. On the plug side you are unlikely to have any need for the neutral (Z) pin as this is only used where 120V loads must also be supported (some 240V household appliances use 120V for their controls and 240V for the main load -- motors, heating, etc., hence the inclusion of the neutral) so you can largely ignore that prong if you opted to retain a 4-pin receptacle type -- if you opted for 3-prong then you will already have capped off this neutral wire and need not be further concerned with it. So on the plug side you will be interested in the two hot conductors and the earth/ground conductor -- essentially wire the green or yellow/green conductor to the earth/ground pin (Z) in your tool's new plug, then the other two wires will go to the two hot prongs (X and Y), which hot goes to which pin does not matter as they are interchangeable.

Just be aware that this is only really safe to do if your power tools are already equipped with fuses or circuit breakers of their own as they are now plugged into a 30A circuit and not the 15A or 20A circuit and breaker they were originally intended for and this breaker will not trip as quickly in an overload condition and in higher impedance faults can allow the much lighter gauge wiring in your tool power cord (which may only be 16 gauge) to exceed the insulation temperature rating possibly resulting in fire if your fault is drawing excess current but not quite enough to quickly trip the larger 30A breaker. If they do not have existing circuit breakers or fuses of their own then you should add motor-rated fuses or circuit breakers to both of the hot legs at your tool (note the "reset" built into some motors is a thermal breaker and not a current limiting breaker, so it does not qualify). Typically the breaker or fuses will be added either within, or in close proximity to the power switch.

If in doubt please either hire a proper electrician or find a friend who genuinely knows what they are doing and what the various requirements and safety considerations are. That said, I wish you all the best!

 

[MichaelSC]

the 14-30 R is a 30 amp plug that has line 1 line 2 neutral, and a ground.
if you are running 220 single phase, which I'm sure you are..... you would connect everything but the neutral terminal. you are using a 20 amp plug, my recommendation would be to change the plug out at the box to a 6-20R receptacle, and skip the adapters. The 14-30R is a dryer type plug, and the plugs to mate it are pretty pricey. This would work for less than $5.00.

https://www.lowes.com/pd/Hubbell-20...-Wall-Air-Conditioner-Power-Outlet/1000050873

 

[Phil S]

The best and safe way to do this is change the receptacle to fit the plug and also (very Important) verify that the circuit breaker is correctly sized for the type of receptacle. It is probably a 30 amp double breaker and must be changed to a 20 amp.

or

Change the plug on the equipment to match the receptacle (none of the linked photos will fit). $20 is really a good price for the correct plug. Buy a good one, not a cheap one. However you should read the equipment specs and connect to an appropriate sized circuit, not an oversized circuit. I suspect you have a 30amp breaker and that is to big for equipment supplied with a 20 amp plug.

I must state that you need to be very cautious about power adapters - make sure your smoke detectors are working well before you do.

 

[Wyatt Co.]

Go wireless.

 

[Brogan]

Replacing the outlets sounds like the best option.
I have no idea why the builder put these in.

If I was to replace the outlets with a 6-20R, I presume there are only 3 terminals - ground and 2 hots?
So I would just leave the neutral unterminated with a wire nut?

Edit: Just saw this:

if you do not need 120V, which is unlikely, then go 3-pin and just cap off the white neutral conductor in the outlet wiring box).

 

[Phil S]

Replacing the outlets sounds like the best option.
I have no idea why the builder put these in.

If I was to replace the outlets with a 6-20R, I presume there are only 3 terminals - ground and 2 hots?
So I would just leave the neutral unterminated with a wire nut?

Yes, but please remember to change the breaker to a 20 amp double - this is an important for fire safety.

 

[Brogan]

Yes, I'll definitely do that.

I presume these are the breakers (I have 2 outlets).

So I would swap them for a single pole 20A breaker for each one.
Which slot would I put the new breakers in, or doesn't it matter?

Presumably I will also need some blanking plates for the empty slots?

 

[MichaelSC]

You will need a 2 pole breaker. 20 amp. Looks like cutler hamer find the 30 amp breaker that goes to the outlet. remove it and replace with the new 20 amp.
The 2 double breakers look like the ones.
you will need ones that look just like them except rated for 20 amps instead.

 

[Phil S]

Yes, I'll definitely do that.

I presume these are the breakers (I have 2 outlets).

So I would swap them for a single pole 20A breaker for each one.
Which slot would I put the new breakers in, or doesn't it matter?

Presumably I will also need some blanking plates for the empty slots?

NO NOT A SINGLE POLE. One of the two dedicated 30 amp double breakers needs to be replaced with a double 20 amp. If you want to convert both of your outlets then both double breakers will need to be changed. If you are in doubt, please have an electrician do this for you

 

[Brogan]

That makes things easy.

 

[junquecol]

Phil's advice is correct. Is your wiring buried behind sheet rock at recpt.or exposed? If it's exposed, why not convert to multi wire branch circuit, with two 110, and one 220, both protected by a double pole 20 amp breaker? The 220 would have to be the first ones, and then fed thru to the 110's, which would have to be GFCI's.

 

[Brogan]

It's under drywall.

I already have enough 110 outlets (albeit 15a) so I'll just switch out the 240 outlets as suggested.

 

[ehpoole]

4

Phil's advice is correct. Is your wiring buried behind sheet rock at recpt.or exposed? If it's exposed, why not convert to multi wire branch circuit, with two 110, and one 220, both protected by a double pole 20 amp breaker? The 220 would have to be the first ones, and then fed thru to the 110's, which would have to be GFCI's.

FWIW, I am really not a fan of using multiwire branch circuits to create an outlet box with both 120VAC and 240VAC treceotacles in the same box, even if only because very few individuals outside of the electrical field understand how the loads across those three outlets add up. I guarantee you that if you create an outlet box that has a pair of 15A 120V receptacles (which athey will know are on different circuits) and a 15A 240V receptacle then there are plenty of homeowners out there that are going to conclude that they may plug their 13A shop vac into one 120V AC receptacle, a 15A router into the next, plus a 12A dust collector in the 240V receptacle and have no idea that there now exist two combinations of tools they may want to power on that will result in a substantial (nearly 180% if a 15A circuit, 135% if 20A) overload of that multiwire branch circuit.

Note that if a 20A circuit breaker is used and there will only be a single 120V receptacle per leg at the outlet box then those 120V receptacles must also be rated 20A (in other words, 5-20r) -- 15A rated receptacles may only be used on 20A circuits where there exist multiple outlets on that same circuit (I do not believe you get to count the 240V receptacle in this configuration).

I do not object to them being used to create two pairs of 120V receptacles that are side by side and on entirely different circuits provided the pair of circuit breakers used are either double pole or clearly labeled as part of a multiwire branch circuit (and, thus, should always be shutoff together). But the moment you add that 240VAC receptacle to the mix you are opening up a giant can of worms as it is not the sort of math that most homeowners will even know that they need to perform each time they wish to turn on more than one load at a time utilizing more than one of those three receptacles and even fewer will know how to properly sum the mix of 120V, 120V and 240V loads to determine if they are still within the circuits designed amperage rating.

 

[Brogan]

Thanks for the input everyone.
All done.

I'm going to need a custom plate though - I may be able to repurpose the original one.