'nuther Electric wiring query

Page 3 of 3  


I do not believe this is allowed by the NEC. If you think about it, each of the two hots will be on 20 amp breakers and will be current limited to 20 amps. The neutral will have to carry the sum of the two circuits, or potentially 40 amps back to the panel. 12 AWG wire is not rated for 40 amps! You may be allowed to do this if you derate the circuit, but I doubt you will want to do this.
Frank
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Geez. Here we go again.
Yes, it is allowed by the NEC, as long as the two hot conductors are on opposite legs of the 240V service, and a single disconnect, disconnects them both. This is easily implemented by using a single double-pole breaker. With the two hots on opposite legs, the current in the neutral is the *difference* of the currents in the individual hot conductors, *not* the sum, and thus can never exceed 20 amps. There just isn't a problem with doing this.
-- Regards, Doug Miller (alphageek-at-milmac-dot-com)
Get a copy of my NEW AND IMPROVED TrollFilter for NewsProxy/Nfilter by sending email to autoresponder at filterinfo-at-milmac-dot-com You must use your REAL email address to get a response.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Fri, 03 Dec 2004 16:56:53 +0000, John Moorhead wrote:

The answer is "yes". Run 12-3 with ground as you said, but use a ganged breaker since if you need to work inside any box, you want both circuits shut off. This is exactly what the electrician did for my gar^H^H^Hshop. All the left hand duplex outlets in each double box are on one circuit, and all the right handers on the other. The 'trician used surface mount boxes and conduit with individual wires rather than romex on mine and ran a seperate ground even though the conduit can be used for ground. I also had him run 2 240V circuits through another single conduit with every other box containing a single 240V outlet and alternating between circuits.
Make sure you have the bottoms of the outlets at least 40" above the floor so you can put standard 36" high benches under.
-Doug
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Fri, 03 Dec 2004 11:53:33 -0700, Doug Winterburn wrote:

Also, make sure the ganged breaker is mounted like a 240V breaker with each half on a different phase so your neutral will never carry more than the load for the biggest drawing circuit.
-Doug
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
"Doug Winterburn" wrote in message

circuits.
You left out an important step ... on most duplex receptacles you MUST remove, or cut, the HOT bridge between the two outlets if you are going to split a circuit.
--
www.e-woodshop.net
Last update: 11/06/04
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

First question: *WHERE* are you? Code _does_ vary, by locale, on whether things like this are allowed.
Comment: this 'two hot, one neutral' wiring is called an 'Edison circuit'. *IS* generally allowed, _as_long_as_ you make sure that the two hot wires go to *different* phases of the main supply.
You do -not- need to 'tag' the red wire as black, btw. anything _other_ _than_ one of the 'reserved' colors (white, green, bare) is presumed to be a 'hot' lead.
I would *NOT* recommend running "12/3" wire. Pull _individual_ wires -- even when pulled at the same time, they go around corners *easier* than the multi-wire cable. You'll likely find that the individual wires are less expensive than the multi-wire cable, too.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Fri, 03 Dec 2004 18:56:12 +0000, snipped-for-privacy@host122.r-bonomi.com (Robert Bonomi) wrote:

I think that is correct. OTOH, sometimes one must tag a white wire as black (hot), such as in a 2-wire (plus ground) 240 circuit or in some 3-way switch configs. -- Igor
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

Right. Technically, it doesn't even have to be marked black; it could be marked any color _other_than_ white, gray, green, or green with a yellow stripe.
-- Regards, Doug Miller (alphageek-at-milmac-dot-com)
Get a copy of my NEW AND IMPROVED TrollFilter for NewsProxy/Nfilter by sending email to autoresponder at filterinfo-at-milmac-dot-com You must use your REAL email address to get a response.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

It is perfectly safe, and does not violate code, as long as: a) the two hot conductors are on opposite legs of a 240V service, *and* b) a *single* disconnecting means will disconnect *both* of them at once. Both of these criteria are easily satisfied by using a standard two-pole breaker: the two sides are necessarily on opposite legs, and one handle disconnects them both at once.
It's not necessary to mark the red wire black, as red wires are assumed to be hot anyway. The conductor color requirements in the code are pretty simple: Ground: bare, green, or green with a yellow tracer Neutral: white or gray Hot: Anything else.

little help here....
You're fine.
-- Regards, Doug Miller (alphageek-at-milmac-dot-com)
Get a copy of my NEW AND IMPROVED TrollFilter for NewsProxy/Nfilter by sending email to autoresponder at filterinfo-at-milmac-dot-com You must use your REAL email address to get a response.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Doug, you seem to know what you are talking about. What's your experience with how often this is actually done? It seems to me that, though legal and safe, someone might forget how this is setup and rearrange breakers/wiring in the future, creating an unsafe situation. Are there any requirements for tagging such a configuration?
Bob
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

'Standard practice' is to run _different_ colors of 'hot' wire. With all the wiring on a given phase being the same color. I use different colors for each hot phase, _and_ unique colors for any 'switched' hot leads. If I have 3 switched leads in the same place, they'll be three different colors -- e.g. 'yellow', 'pink', 'blue'. With this kind of set-up, if you find a 'non-red/black' - neutral pair, you *know* you can't _trust_ that the *circuit* is dead, just because there's no power across the pair. Gotta find the switch (or switches!!) first. and check _there_.
Any competent electrician, does any breaker 're-arranging' only _within_ a single color. Or *thoroughly* investigates the details, and then 'marks' *both*ends* of any wires that get 'moved' to a different phase. *AFTER* having made sure that neutral load currents are _not_ exceeded.
This is practically 'no-brainer' stuff for a professional. The amateur that doesn't understand stuff at this level, should *not* be messing in the panel. <grin>
This is also why =many= communities have a 'basic wiring' test that you have to pass, _as_a_homeowner_, before you can get a permit for 'do it yourself' work. These exams are _not_ difficult -- their primary purpose is to ensure that you know enough to not to anything 'dangerously stupid' in _residential_ wiring.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

It seems to me that it's a pretty common thing. There are no requirements for tagging it that I'm aware of, but if it's wired properly (double-pole breaker, and 12/3 wire, with red and black hot wires) the installation itself should be sufficient to identify it as what it is -- and with a double-pole breaker, it's impossible to break it up by rearranging the breakers.
-- Regards, Doug Miller (alphageek-at-milmac-dot-com)
Get a copy of my NEW AND IMPROVED TrollFilter for NewsProxy/Nfilter by sending email to autoresponder at filterinfo-at-milmac-dot-com You must use your REAL email address to get a response.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Fri, 03 Dec 2004 23:00:24 GMT, snipped-for-privacy@milmac.com (Doug Miller) wrote:

Doug is absolutely correct in his posts on this, IME. In fact consider that if someone wanted a "group" of outlets in one box from two circuits, 12/3 would be the safest way to do it (with all Doug's caveats about the breakers). (It may be required under the NEC to have all hot wires within a box controlled by the same breaker, or paired breakers, but I have unfortunately encountered boxes that are hot from separate breakers.) It is common in my non-pro experience to use 12/3 to run series of outlets along a counter, switching circuits back and forth along the way. For example, in a kitchen. -- Igor
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

The NEC requires that all ungrounded conductors be capable of being disconnected simultaneously by a single disconnecting means. A single, two-pole breaker is by far the easiest way of achieving this, but it isn't the only method that complies with that requirement. E.g. two widely separated single-pole breakers, connected with a rigid handle tie, would satisfy.
-- Regards, Doug Miller (alphageek-at-milmac-dot-com)
Get a copy of my NEW AND IMPROVED TrollFilter for NewsProxy/Nfilter by sending email to autoresponder at filterinfo-at-milmac-dot-com You must use your REAL email address to get a response.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
"John Moorhead" wrote in message

To get a precise answer, it is important that you clarify this. Do you want to be able to plug in two, or four, plugs in the box?
--
www.e-woodshop.net
Last update: 11/06/04
  Click to see the full signature.
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.