I have an Edison circuit with 12/3 wiring feeding a duplex outlet with one circuit and associated outlet dedicated to a basement freezer. The other outlet of the duplex pair is on the other leg and used for general purpose.
Can I continue the wiring from that one leg to feed other outlets downstream using 12/2 wiring (dropping the conductor for the dedicated freezer outlet) or do I need to continue to feed the 12/3 wiring everywhere?
Note the outlet box with the split Edison duplex is labelled as such.
Absolutely! The one thing that you must do with an Edison circuit, is pigtail the neutrals, as the Nec doesn't allow their integrity to be dependent upon a device. Once you break them into two 2 wire circuits, you just wire them as you would any 2 wire circuit.
Am I right to interpret that you only need to pigtail the neutrals while it's still an Edison circuit (i.e., while both phases enter a box on 3 conductor cable and feed different devices in the same boxe). But that once I am beyond the shared box and onto a regular 2-conductor circuit then I don't need to pigtail neurtrals any more but can daisy chain through devices again?
Or does every junction on the circuit need to have the neutrals pigtailed rather than daisy-chained?
Also, while you are at it, are there any other code 'gotchas' that I should be aware of with Edison circuits?
You are correct about the neutrals. The newer Nec requires that Edison circuits be on double pole breakers, essentially to insure that your hot legs are on different legs of the service.
The problem is that, as long as that freezer duplex outlet is a split receptacle, you need to have the two hot legs on linked breakers. That means that if anything on your new receptacles tripped its breaker, your freezer's breaker would go out. This is not good wiring practice, and may actually be against code, in that code often requires such things as freezers and sump pumps to be on their own circuits, for obvious reasons.
You should plan to quit using the other half of the outlet that's at the freezer, in fact I'd put a simplex outlet in there. Then rewire that outlet so it's entirely on one leg; the red leg, say. Then I'd run all the downstream outlets off the black leg. You'd put one of them close enough to pick up whatever you were plugging into the other half of the freezer outlet.
Now, because you don't have both legs feeding any one "strap" (ie, any two outlets on the same duplex device) I *think*, depending on the exact wording of code that applies in your area, you can now unlink the two breakers. Of course you must make sure the two hots are on different legs of the panel, but that *really* should already the case (check it, while you're at it). You should probably change the label on the freezer outlet to say something like "power in this box is controlled by two separate breakers".
Yes - because while having them trip at the same time is a safety feature (and a good idea). Having them on opposit legs is a safety necessity because otherwise you run the risk of having 2x the current on the common neutral. So a 12-3 would be carrying up to 40A. While if the
2 hots are on opposite phases, then there is actually no net currrent flowing in the neutral when the hots are maximally loaded.
That is a good practical point. But luckily I don't use that other outlet much. And since it is a basement freezer, I'm not sure the NEC applies as it would in the kitchen. But I'm just guessing on that. Nevertheless, I will think about your point...
That is how it is wired now - with the exception that I added a bar to tie the two halves together (which as you pointed out has some negatives).
If there are 2 separate breakers with a handle tie, tripping one breaker may or may not trip the other breaker. (With a multipole breaker all poles will open.)
As Doug said, the NEC has no such requirement.
The same NEC requirements apply.
The requirement to have a "simultaneous disconnect" for an Edison circuit starts in the 2008 NEC. Before that, if 2 circuits were connected to the same duplex outlet you needed a simultaneous disconnect
- probably starting with the 2002 NEC. Before the 2002 NEC you didn't need a simultaneous disconnect. Whether you need a handle tie (or multipole breaker) depends on what code was in effect when wiring/changes were done.
If the receptacle was not split-wired and was there before the 2008 NEC was in effect you don't need a simultaneous disconnect. If you extend the circuit you probably do.
The change was not based on having the wires on different legs. As I said, it was based on totally disconnecting the circuit to avoid "hot neutrals". It is one of the changes based on a dead body - in this case an electrician. Dead bodies are effective in promoting code changes. One of the change proposals came from OSHA, which probably also helped.
Maybe we should just make all circuits like UK construction sites, which I believe are 120V with the transformer center tap earthed. There are 2 hot wires both 60 volts to ground.
Please bear with me here... I thought the purpose of the "handle tie" was to ensure that tripping one pole tripped the other. Of course, there is always the possibility that the "spring" won't be strong enough to trip both but I thought that at least "in theory", tripping one should trip the other. If not, then what is the purpose of the "handle tie" other than perhaps to serve as a glorified visual notice to anybody opening the panel that the circuits are connected.
I'm a little confused. Per NEC, does a handle-tie count as a "simultaneous disconnect" or does only a multipole breaker count? If not, when did a handle-tie stop being code-approved for Edison circuits?
In other words, are you saying that a multipole breaker is a code requirement or just that in practice a multipole breaker is likely to be more effective and a good idea versus a handle-tie?
There's an internal mechanism to cause a common trip, even when the tie between the handles is broken. I discovered this after I tried removing the tie to convert the double pole breaker into two singles. I was able to shut off one side at a time, but when one side tripped, both sides went tint trip mode.
The purpose of a handle tie for separate breakers is to guarantee both breakers are "simultaneously disconnected" (the code requirement) so the entire Edison circuit is dead for service work.
I have fairly often turned a breaker on when there is a short. The breaker trips while my thumb is still turning the breaker on - the handle is on and the breaker is off. This is a necessary feature and is called "trip free". Also prevents someone from 'holding' a breaker on when it should be tripped.
When the breaker trips like that I don't feel any particular pressure on my thumb. The mechanism in the breaker has to open the breaker. It does not have to trip a breaker that has been ganged with a handle tie (but some breakers might).
If you want a common trip use a multipole breaker. The common trip, as Bob wrote, is internal - the breaker has been designed to trip all poles.
The handle tie is to "simultaneously disconnect" (the code requirement) all of the circuit so the entire circuit is dead for service work. That is clearly why the "simultaneous disconnect"requirement, which previously applied to Edison circuits that supplied a split wired receptacle, was extended to the entire Edison circuit in the 2008 NEC. (It is clear if you read code change proposals and action of the code panel.)
Both a multipole breaker and separate breakers with a (listed) handle tie comply with the "simultaneous disconnect" requirement in the NEC.
A multipole breaker is only required if you want a common trip. You want a common trip for a 220V device like a clothes dryer.
For an Edison circuit the NEC only *requires* a "simultaneous disconnect". Use a multipole breaker if you want to.
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