Jim W in Tampa
Senior Member
- Location
- Tampa Florida
Could 10-4 mc ,"black,red,blue,white,green" be used to get single phase 30 amp dryer receptacle and a 120 volt 20 amp receptacle for the washer ? Neutral used for both.
10-4 mc for dryer /washer
- Thread starter Jim W in Tampa
- Start date
- Status
- Location
- Massachusetts
Yes if you have a 3 phase source and if you can figure a way to handle tie a 2 pole 30 and single pole 20 together.
Jim W in Tampa
Senior Member
- Location
- Tampa Florida
No ,source is single phase. My thinking is that neutral usually has little on it from dryer.
- Location
- Massachusetts
Well I agree it would work and very likely be safe but your defiantly on thin ice with the code.
Jim W in Tampa
Senior Member
- Location
- Tampa Florida
yes know its on shaky ground but was curious if legal . Can you think of any code number it directly violates ?
Under normal circumstances, it would probably work, and work well.
But you could, considering a worst-case scenario, create a 50a fault on the neutral. One side of the 30a 2-pole has no current, and the other has 30. Couple that with the 20a for the laundry circuit, you've exceeded the amperage of the neutral conductor.
So I would say 310.15 might come into play as you have the potential to cause 50amps to flow on a #10.
But you could, considering a worst-case scenario, create a 50a fault on the neutral. One side of the 30a 2-pole has no current, and the other has 30. Couple that with the 20a for the laundry circuit, you've exceeded the amperage of the neutral conductor.
So I would say 310.15 might come into play as you have the potential to cause 50amps to flow on a #10.
- Location
- Massachusetts
Along those lines I think you run up against 240.4(D) with 50 amps of OCPD protecting the 10 AWG Neutral.
Jim W in Tampa
Senior Member
- Location
- Tampa Florida
Agreed could under misuse be used wrong and have 50 amps on neutral. Was just a crazy idea to solve a wiring problem. No big deal will run washer from another easy to get at location.Too bad wasnt doing this under older code of 3 wire dryer. But that would be worse since they are on a sub panel and next to each other.
hillbilly1
Senior Member
- Location
- North Georgia mountains
- Occupation
- Owner/electrical contractor
The drum motor on the dryer is 120 volt, thus a fair load on the neutral. Don't know the reasoning behind it, unless they have changed it lately. So you would have two 120 volt loads on the neutral, unless you luck out and their one opposite legs. Still would not meet code unless you have an oversized neutral, or it is a three phase feed.
Jim W in Tampa
Senior Member
- Location
- Tampa Florida
Actually dryer motor would only be a few amps . The danger would not be from any normal washer and dryer. But with adaptors someone could missuse the dryer receptacle to carry some other load. With proper use would be no problem as the dryer would never have more than few amps on neutral.
Same danger is on most houses with derated neutral.
- Location
- Massachusetts
The motor in an electric dryer is a very small percentage of the load.
By making the motor connected line to neutral it will not matter if you supply the dryer with 208/120 (common in apartments) or 120/240, either way the motor gets a full 120. A 240 motor is really not deigned to run on 208.
The heating element can deal with either 240 or 208 with a reduced heat output.
hillbilly1
Senior Member
- Location
- North Georgia mountains
- Occupation
- Owner/electrical contractor
I did not say it was a large percentage of the load, compared to the heating elements it is not, what I was referencing was that it is a 120 volt load which would be added to the neutral load of that of the washer. This was what we were discussing, overloading the neutral. The combined load would probaly not overload the neutral anyway. But that load has to be kept in mind.:smile:
Jim W in Tampa
Senior Member
- Location
- Tampa Florida
Only reason i gave it a thought was because i have enough 12-4 in my shed to make the run. Seemed like a waste but just will not use the blue. We simply need and extra washer / dryer and will be a real pain to run it.
You're going to use 12 for an electric dryer?
winnie
Senior Member
- Location
- Springfield, MA, USA
- Occupation
- Electric motor research
As I recall, OCPD is permitted on the neutral, as long as it opens the ungrounded conductors.
Of course, you could always use a rotary converter to produce three phase...
-Jon
Of course, you could always use a rotary converter to produce three phase...
-Jon
wwhitney
Senior Member
- Location
- Berkeley, CA
- Occupation
- Retired
So if you were willing to rewire the dryer to have two plugs, one 240V only and one 120V, so that you could control which leg the 120V dryer loads are fed from, could you make an NEC compliant install?
Cheers, Wayne
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
For that matter, just install a small sub-panel in the laundry room.
hillbilly1
Senior Member
- Location
- North Georgia mountains
- Occupation
- Owner/electrical contractor
You would be violating the UL listing by rewiring it. If you ran a #6 neutral, with two #10 hots for the dryer, and a #12 hot for the washer, and had a common handle tie to comply with 08 code, you could do it without rewiring the dryer. Not very practical though.
Jim W in Tampa
Senior Member
- Location
- Tampa Florida
ooops 10 ----------
- Status