220 volt in parallel ??

[Benjimin Young]

I have an exisiting 12 ga 2 wire feeding a single pole 750 watt baseboard heater in my shop. The wire (about 60 ft) goes from a 15 amp 220 volt breaker, blk on on hot, red on other hot, and ground to ground.

Obviously the wire and breaker can feed a lot more capacity. I would like to install a 15 amp 220 volt single pole receptacle to power my dust collector.

The plan is to cut the wire (lots of slack) near the heater and install a typical junction box for the receptacle and run the wiring parallel through the box to the heater. I have never wired 220volt in paralle before. Will this work?

Excuse the very rough diagram.

[Hoa Dinh]

240V in parallel is no difference from 120V in parallel.

Your plan will work, at least technically.

I don't know anything about code-compliance.

[Lars A Stole]

Theoretically, no problem. I just did a similar job to break a 220v receptacle into two outlets.

The concern, if there is one, is that your 60 ft of 12g may be a bit thin if you are going to draw 15amps using your dust collector (i.e., 3HP running constantly). 750 watts of 220v is probably in the neighborhood of 3-4amps, so you need to add that into the math. That said, I think the standard is 12g is good for 100 ft of continuous 20amp current so I wouldn't think it a problem if you have a 2HP collector. Any electricians want to chime in with the definitive rule?

[Ryan Myers]

You shouldn't load your breaker or wire beyond 80% continous load. On 20A 240V circuit you have 4400 available watts. You should strive to keep your load at 3520 watts or below. A 3PH motor @ 240 will draw around 15 amps = 3600 watts. A 2HP motor @ 240 will draw around 10 amps or 2400 watts. As long as your dust collector is 2 hp below combined with a 750 watt heater you will be fine. There is no code requirements on the max number of receptacles per circuit for 120V or 240V. You will need change out the breaker to 20 amp. Just make sure your absolutely sure the wire is 12 gauge before changing the breaker. Otherwise you have a recipe for disaster.

[Benjimin Young]

Thanks all for the help.

I completed the hookup of the 220/15amp receptacle and all works well however a quick check with an amp meter (heater and DC running) shows a n approximate draw of 16 amps on each hot wire at the panel. Note, I did double checked that the wire is 12ga and my DC is a 3HP E rated motor labled as 12 amps. Obviously the DC never runs unattended however the heater does.

Question. I was thinking the 15 amp breaker would just pop if overloaded and therefore be the weakest part of the circuit (as oposed to overheated wire, etc.). Is it safer to leave the 15 amp breaker or change to 20amp breaker?

Ben

[Randy Denby]

Depends on the breaker....I've got "Federal" brand breakers, and I can arc weld the wire to ground and they still wont trip. I think the 15 amp breaker on your amp draw is gonna be nuisance tripping if it's a good breaker, cuz your right at the limit. But it wont hurt anything to try it out as long as the wire is 12 gge.

[Ryan Myers]

Your biggest problem will most likely be when the heater is running and you start the DC. The inrush current when the motor starts can be many times of running current draw. Most circuit breakers will allow current draw a few amps beyond the rating. I would suggest changing the breaker, because it is going to eventually trip.

[Stan Mijal]

Ben,

Everything you have stated sounds ok to me. The upgrade to a larger breaker capacity providing the wire is sized accordingly is good common sense.
When I wired my garage/workroom I was going to have more than one 220v outlet on a circuit. The inspector would not let me do that( and I really did not want to push the point by asking where the code specifies this)so I would suggest you contact your local builing department to see if they would permit this.

[Jim Becker]

It's always been my impression that things like hard-wired heating systems needed to be on a dedicated circuit...check with a licensed electrician familiar with code on this. Even though you may be able to do something physically doesn't mean it's a good idea to do so...

[Travis Lavallee]

Also I think there are maximum allowable receptacles on a circuit, I think it is 12 for a 15A 120V circuit, but don't take that as the truth. Someone who knows the code better will be able to tell you, but you can't just add unlimited receptacles to a circuit.

[Rod Sheridan]

Code requires that circuits not be loaded past 80% continuously, or when connected to thermostically controlled loads (heaters.

Your 15 ampere breaker is too small, it can only carry 12 amperes.

A 20 ampere breaker can carry 16 amperes, just perfect for your application.......Rod.

[John Terefenko]

No more than 6 receptacles. Just think if there was no limit how much you can overload a circuit.

[Brian Dormer]

Maybe the best course of action would be to hire a local licensed electrician (or home inspector with an electrical background) to inspect what you've done. You don't necessarily have to tell him/her that YOU just did it. You don't really have to say anything - just lead them to it and let them inspect it.

If there is anything wrong, they will tell you what's wrong and (probably) suggest what it will take to fix it and/or make it code compliant.

Don't forget, if this rewire causes a fire - your insurance may not pay up.

bd