How To Adapt 4 Wire To 3 Wire 220 Volt?

[ScrewyBrewer]

I currently use a dedicated 30 amp 220 volt 4 wire GFCI outlet in my unheated garage brew room to power up my RIMS kettle. It's been in the 20-32F range here and will be for the next several months. I'd like to use a 220 volt 5000 watt electric heater to keep the brew room warm in cold weather but all the models that I've looked at come with a 3 wire 240 volt plug end.

I want to buy a 4 wire dryer plug cord and rewire the electric heater so it can plug into my existing 220 volt outlet and save the cost of having to add another 220 volt line. I'm not a stranger to electrical wiring, but I'm not sure how the 4 wires should be connected to a heater that comes with a 3 wire cord.

Has anyone ever heard of, or safely done anything like this before? I'm sure if anyone has faced a similar problem it would be a home brewer, any help or ideas will be really appreciated.

 

[ajdelange]

The three wires on the heater will be two phases (hots - red and black in the outlet box) and the frame ground (bare, green or green w/yellow stripe in the box, green or green w/yellow stripe in the heater cable) so those are the wires you need to connect to in the plug. You will not connect the neutral (white wire in the outlet box). The ground blade is the L shaped blade in a NEMA L14-20 or L14-30 plug or the D shaped pin in a 14-20 or 14-30 plug. The attaching screws are usually marked X, Y (for the two hots), W (for the neutral - the one you don't use) and G for the ground and are often colored (brass color for the hots, silver for the neutral and dull gray for the ground).

As always I feel it necessary to state my standard caveat: if you have to ask questions like this you probably shouldn't be fiddling with electricity. Get someone who is savvy or a licensed electrician to do this for you.

 

[AnOldUR]

If it were me, I’d install the proper receptacle, At the very least, make a short adapter cord. Like ajdelange says, a 240V heater doesn’t require a neutral.

I'm sure you're aware that most 240V heaters will come close to the max of your 30 amp circuit You won’t be able to use it while you’re brewing.

 

[ScrewyBrewer]

Thanks folks! I think I just needed confirmation from a few knowledgeable people before deciding on my plan of action. I found an image that I think aligns with what you've posted and I do appreciate the precautionary comments as well as the technical details involved.

I'm leaning more now towards making up a short 'adapter' cord instead of tinkering with the internal wiring of a brand new heater. I don't plan on using the kettle and the heater together at full capacity and exceeding the 30 amp rating of the circuit.

Thank you for helping me with this and for responding so quickly, if I can ever repay the favor please just let me know.

 

[ajdelange]

That looks good and you will still be able to plug the heater into any 'standard' 220V outlet when not using it in your garage.

 

[The10mmKid]

Looks good Screwy,
Your diagram is correct.

I am however not in the 'adapter' camp.
An adapter adds too many connections which can become loose, can overheat, and cord grips get stressed, etc. (Not to mention the 'hacked' look)

If you bought this heater for the purpose you mention, cut it's plug and install the 4-wire type.

Just my two-cents and years of seeing charred wires at screw terminals and crappy cord grip work.

Happy New Year,
'da Kid

Thanks folks! I think I just needed confirmation from a few knowledgeable people before deciding on my plan of action. I found an image that I think aligns with what you've posted and I do appreciate the precautionary comments as well as the technical details involved.

I'm leaning more now towards making up a short 'adapter' cord instead of tinkering with the internal wiring of a brand new heater. I don't plan on using the kettle and the heater together at full capacity and exceeding the 30 amp rating of the circuit.

Thank you for helping me with this and for responding so quickly, if I can ever repay the favor please just let me know.

 

[AnOldUR]

These guys will make you one, but it's pricey.

NEMA 14-30 Male Plug
NEMA 6-20 (T-Slot) Female Connector
Comes to about $95 depending on the wire

Better searching might find a better price.

 

[ScrewyBrewer]

Just wanted to provide my latest update since yesterday. I ended up buying a 4 wire electric dryer cord that is compatible with my existing 220 volt wall outlet. The store had only one 220 volt 5,000 watt wall mounted heater left, it was on display and I was able to buy it for 10% off.

I'm happy to say I've got a heated garage brew room now and it really feels good doing stuff out there without having to be all bundled up. The heater is made to be wired directly so any 220 volt cord or plug type can be used as long as the wire is 10 gauge or sized to handle the 22 amp load. The dryer cord even came with a metal clamp used to secure the wire to the rear panel of the heater.

The green plug wire I tied to the heater's internal ground wire with a wire nut. The black plug wire went to the heater's L1 and the red wire went to the L2 lug. The white cord wire I capped with a wire nut and a wrap of electrical tape after cutting the copper flush with the wire's insulation and tucked it safely out of the way.

I bought the "King 5000-Watt Electric Garage Heater with Thermostat" and the 4 wire dryer cord for just around $200.00 and was able to save at least that much on labor by doing the work myself. The heater is made in the USA, runs very quiet, is controlled by a thermostat and easily heats a 20 x 20 garage with 10 foot ceilings.