Can you use white for one leg of 240V circuit?

Page 1 of 5  
OK, here'e the questiond du jour. Was helping a friend and when we took off the circuit breaker panel cover we discovered that for both AC units, whoever did this used white for one of the 240V hots. There is no tape or tag to identify it as a hot. Is this allowed by code? Even if it is, seems bad practice to me. I would have used either red or black.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

No. With tape or paint, it would be.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Mon, 02 May 2011 00:45:44 GMT, snipped-for-privacy@example.com (Doug Miller) wrote:

I have some (un)Sharpies in my electrical toolbox to mark wires.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Yeah, same here. Better than tape.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Mon, 02 May 2011 02:01:27 GMT, snipped-for-privacy@example.com (Doug Miller) wrote:

First post I have seen from you in a while, Doug. Have you been well?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 5/1/2011 7:40 PM, snipped-for-privacy@optonline.net wrote:

If you see a 10/2 with ground hooked to a two pole breaker on one end and disconnect for an AC condensing unit, water heater or dryer plug on the other end, you pretty much know that the white wire is another 240 volt leg. You can wrap a piece of black tape around it if you like but most electricians don't bother because the wires are in the same jacket. If it's a loose wire pulled into conduit and the installer didn't have a red wire and used a white instead, it's going to be marked with a strip of black or red tape every 6 inches or so to indicate it's another hot leg. You may see green tape on a black or white wire to indicate it's being used as a ground. You will see this on larger sized loose wire where the conductors are all black and each is marked with red, white or green tape to indicate their purpose. It all depends on the inspectors in your area. Around here what I wrote will pass inspection but may not in another jurisdiction.
TDD
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

And if you do, that's a code violation AFAIK.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On May 1, 10:02pm, snipped-for-privacy@example.com (Doug Miller) wrote:

It is not a code violation on conductors larger than number six American Wire Gauge. He did say that "You will see this on larger wires..." -- Tom Horne
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

I agree with you, although, you should NEVER have a 10/2G feeding an electric dryer, unless you can find a piece of 10/2 SEU copper, which I've never seen. Despite the code, it is extremely rare that I ever see the white wire remarked
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

You haven't seen the runs to my shop tools. ;-)
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

It is not legal to use 10-2 for a dryer because there is a neutral load. You need to have an insulated wire for the ground/neutral. The same is true for a range if there is a neutral load.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

Exactly, with the exception of type "SE" cable, originating from the main service panel
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 5/1/2011 9:12 PM, RBM wrote:

I've seen it for years but as of late the rule change calls for a four wire circuit. Years ago I installed a lot of dryers with 10/2 w/gr but now I use 10/3 w/gr or 8/3 w/gr. The smallest aluminum SEU you can run in a house around here is #2 which I often use for stoves. Moving an old dryer to a new location has us removing the old 3 wire cord and plug for the 4 wire cord and plug. I often run 10/2 w/gr to the disconnect for a 2 ton condensing unit and never bother to mark the white wire because it's in the same jacket as the black and ground.
TDD
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

10/2g is fine for hot water heaters, or A/C units. It has never been acceptable for an electric dryer, because the ground/neutral was required to be insulated. The only exception was using SUE cable, originating from the main service panel
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 5/2/2011 5:37 AM, RBM wrote:

I could swear the darn things have been hooked up for years with a 3 wire plug and 10/2 but I do go with a 4 wire hook up now. The last one I installed was in a restaurant where I ran EMT 3 #8's and a #10 ground. The last one I installed in a home was an 8-3 w/gr Romex circuit with the four wire receptacle. I used #8 because it was on the far end of the house, short runs to a dryer get 10-3 w/gr and 4 wire plug and cord.
http://preview.tinyurl.com/3ff8ata
http://preview.tinyurl.com/3pmzqgc
TDD
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

** The issue isn't the 3 wire plug and cord set. You just can't connect it to 10/2g Romex. To be Nec compliant, it had to be connected to 10/2 service entrance cable, which I've never seen in copper, so it would typically be connected to 8/2 aluminum service entrance cable.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 5/2/2011 8:04 PM, RBM wrote:

I think I mentioned it before, around here, the smallest aluminum SEU cable the inspection service will allow is #2. I would run that to the stove because it's cheaper than copper, which I think for a 50 amp load is #6.
TDD
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Actually 10/2 with a three prong plug was acceptable for dyers for a long time. Dryers have a metal strap inside them that connected neutral and ground together. The code now calls for a 4 prong plug and 10/3 with ground now. But I'll bet there are still millions of 3 prong installations out there. I don't know if replacing the dryer meet the code requirement to upgrade to 10/3 since you are not actually touching the circuit any. Existing circuits do not have to be upgraded to meet newer code releases.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

He was talking about moving the dryer not just replacing it. -- Tom Horne
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I didn't see anything in the thread about moving a dryer? The op mentioned it related to the ac compressors. On pure 240 circuits such as an ac compressor use of 2 conductors with a ground always has been and is still accpetable. Same is true for hot water heaters. New wiring for appliances that use both 240 and 120 such as stoves and electric dryers now requires 3 conductors plus ground. And a 4 prong outlet. RBM stated that 2 condutor with a ground was never accpetable for dryers and that's just false. For many years dryers were wired using 10/2 and the strap inside the dryer connected neutral and ground together.
If you move the dryer outlet that is a change. Any changes to an existing circuit must be borught up to current code. If the original cicuit has 10/2 then a new piece of 10/3 will have to be run.
What I'm not so certain about is simply replacing the appliance. SInce it's a plug in appliance replacing it is not a change to the circuit. I would expect that you could continue to use the older 10/2 circuit.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Site Timeline

Related Threads

HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.