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US electrical supply question

Split 15A receptacles in kitchens are actually quite common and approved in most jurisdictions; as mentioned above, the neutral only has to carry the imbalance between the two phases.

http://www.electrical-online.com/kitchen-split-receptacle-circuits/

But these days GFCI (and sometimes ACFI)-protected single-phase 20A circuits are the norm.

As an only marginally relevant aside: if your existing circuit is only two-wire with no ground, many jurisdictions approve a GFCI
instead of a grounded receptacle as long as it is clearly marked as not being grounded.

m
 
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And, I just checked my notes. The hots on the two 3 wire circuits come off of breakers that are directly one above the other, so are on different phases, assuming a normal breaker box.

Technically, the breakers should be mechanically coupled, so I'll look into that, but otherwise I'll leave the box alone.

I'm learning a lot here, having always been used to just having a single phase in a building.
 
MikeS said:
Split 15A receptacles in kitchens are actually quite common and approved in most jurisdictions; as mentioned above, the neutral only has to carry the imbalance between the two phases.

http://www.electrical-online.com/kitchen-split-receptacle-circuits/

But these days GFCI (and sometimes ACFI)-protected single-phase 20A circuits are the norm.

As an only marginally relevant aside: if your existing circuit is only two-wire with no ground, many jurisdictions approve a GFCI
instead of a grounded receptacle as long as it is clearly marked as not being grounded.

m
Click to expand...

Well, even though the guy you cited is Canadian, I'll concede this one, though I don't much like it. :)

Just make sure that the hots are coming from opposite sides of the line; otherwise, this would amount to a parallel hot and a single neutral. A 2-pole breaker would ensure the feeds were split-phase.

Most US jurisdictions would flag you for having an ungrounded outlet. Some don't allow the old 2-prong outlets, period. I recall that a relative had to have an apartment building he owned re-wired because of the lack of grounded outlets. To be fair, it was set up with the old knob-and-tube wiring. US jurisdictions take NEC/NFPC and modify it to their own needs. For example, where my parents had their house, residential wiring mandated use of EMT--none of this Romex or BX stuff. You can bet that ran construction costs up.

In spite of the "National" in NEC, there is no federal law requiring adoption of any part of that code. Insurance companies, in most cases, will dictate what needs to be enforced--and the opinion of the local inspector might as well be law. You can go blue in the face citing NEC and get nowhere.

In my area, electrical baseboard heaters are the cause of many residential fires. People pile pillows or cushions up against them.
 
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Chuck(G) said:
A 2-pole breaker would ensure the feeds were split-phase.
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That was my first thought, using a GFCI breaker, but I can't do it as it would put the common neutral on the load side of the GFCI. I will see about mechanically coupling the two regular breakers in each pair. The pair in the newer box will be easy - you just drop a pin through holes in the two levers, turning two single pole breakers into a single 2-pole breaker.

The older one, not so much. Several of the breakers in the older box are (I don't know the correct term) "2-in-1" breakers. As in, they have two levers and feed two (presumably lower current) circuits from a single breaker position. I might have to swap some wires around in the breaker box, to let me mechanically couple the two that feed that 3-wire circuit.

Before I can do that, though, I'll need to get her to figure out what equipment she's going to be placing where. Given that some of the circuits may have only half the capacity that you'd expect (I won't know for sure until I look at the wires) it's probably a good idea to look at all the circuits on "2-in-one" breakers anyway.

The inspector is being quite decent, letting us get away with GFCI receptacles. I can fit them myself, in my capacity as "the maintenance guy", whereas running a second neutral would require a licensed electrician. He actually said to me, when we were alone for a moment, "You can do that." (meaning the receptacles, not running a line).

There are also a couple of outlets that she won't need, are wired very poorly (Romex hanging in open air, a dodgy disconnect, etc). I told her that I wanted to get rid of those altogether and she concurred.

I haven't enjoyed myself this much with electrics since we lived in England, when I electrified one of our garden sheds, to turn it into a workshop. I learned all of the math around exporting an earth (ground), ran the numbers, did the job properly and then promptly forgot everything!
 
gekaufman said:
Agree, and I believe code requires a double pole breaker to make sure both legs are shut off at the same time (and on opposite phases).
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Yes, as mentioned above, I can do that easily with one box but will have to swap some shizit around in the other box, in order to make that happen.
 
I guess electrical safety in the US has been updated somewhat:
Testing1.jpg
 
If your testing the AC mains, the old radio engineer's safety rule applies---one hand in a back pocket.

What impresses me is the guys who work on the distribution stuff. Last year, when a fuse when in our pad-mounted transformer on the 12KV side, I watched the guy from the co-op do the replacement. He used a 10' fiberglass pole to unscrew the fuse from the transformer base and cautioned me to stand back while he inserted a new one using the same pole. He said that if there was a short in the transformer, the fireworks could be spectacular. The fact that they were working on the same 12KV lines 30' in the air during an ice storm instilled a whole new sense of respect for them. I've still got a hunk of the underground cable they wired the transformer up with--it's all copper and about as big as a garden hose. Heavy stuff for heavy current.

I can't imagine what working on a 500KV or 3MV line is like.
 
roberttx said:
I did a little bit more examination, yesterday. The three wire circuit terminates at two double outlets in a single wall box. Each has a different hot and they share a common neutral, delivering 115V at each outlet. The breaker box end is messed up. One hot is on one half of a "2-in-one" breaker, the other is on one half of a different "2-in-1" breaker. I think I should pull some breakers and swap some wires around and just not tell anybody that I did so.
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You really should think about getting a qualified and licensed electrician to look at it, as this is what they do for a living. Paying an electrician to do it right will cost a bit, but for a business it is worth it from an insurance standpoint.

For multiwire branch circuits, the relevant paragraph that directly affects what you've just described is 2017 NEC Article 210.4(B) Disconnecting Means, which says, in part: "Each multiwire branch circuit shall be provided with a means that will simultaneously disconnect all ungrounded conductors at the point where the branch circuit originates...." Single-pole breakers may be used for this purpose as long as there is an 'identified' handle-tie between the two poles, as provided by 2017 NEC Article 240.15(B)(1). This type of circuit is illustrated in the 2017 NEC Handbook on page 63.

NEC uses very specific definitions of these terms:
1.)Shall. Means 'you absolutely have to do this, no ifs, ands, or buts, do not pass Go, do not collect $200.'
2.)Ungrounded conductor. This is a currently-carrying circuit conductor that is not bonded to the grounding conductor and is typically what most people call a 'hot' conductor; there is a such thing as a 'grounded hot' in certain cases, such as corner-grounded 'neutral-less' delta three-phase (got one of those circuits at $dayjob).
3.)Grounded conductor. This is a conductor that is bonded to the grounding conductor at one point. Typical US single-phase two-pole power (120/240) has the neutral or transformer midpoint grounded at the service entrance by the ground bond to the grounding conductor, but there are several exceptions in industrial settings, especially once you graduate to medium-voltage stuff like some of the 2,400V stuff here at $dayjob.
4.)Grounding conductor. This is a conductor that is tied to earth ground via one or more bonded electrodes; the grounding conductor is not allowed to carry circuit operating current but only fault current.
5.) Identified (as applied to equipment). Recognizable as suitable for the specific purpose. This isn't as strict as 'listed' but, in the specific case of handle ties, a simple wire or pin pushed through the holes in the single-pole handles didn't satisfy one inspector I dealt with; she said that the handle tie had to be designed for that specific breaker or a recognized (by the Authority Having Jurisdiction or AHJ) 'compatible' breaker. That particular AHJ recognized several plugin breakers as being compatible; GE and Siemens, for instance, for a particular panel type could use the same handle ties, but they had to be actual 'handle ties' manufactured for the purpose. Maintenance had put a piece of 12AWG copper wire through the tie-hole with bends on each end, and that didn't pass. An 'identified' handle tie for GE THQL 1-inch breakers looks like https://www.amazon.com/THT104-GE-CIRCUIT-BREAKERS-THT104CP/dp/B007937DDS/

Would you mind sharing a pic of that '2-in-1 breaker' you mentioned? I've seen some of these; four poles in a two-pole space, with the center two poles handle-tied and the outer two poles handle-tied. Is that what you see?
 
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I thought the 2-in-1 breaker being referenced was a pair of half-width breakers that tie to a single phase. Mostly used in crowded Square-D panels to save space. Nothing wrong with them if used correctly. Of course, completely unsuitable for 240V loads.

"Grounding" is an interesting topic. IIRC, NEC allows you to try driving grounding rods into soil twice--and then to say "aw, screw it" if you can't get a good ground.
 
Chuck(G) said:
I thought the 2-in-1 breaker being referenced was a pair of half-width breakers that tie to a single phase. Mostly used in crowded Square-D panels to save space. Nothing wrong with them if used correctly. Of course, completely unsuitable for 240V loads.
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The breaker I was envisioning is like this one, from Eaton:
https://www.homedepot.com/p/Eaton-One-20-Amp-2-Pole-and-One-30-Amp-2-Pole-Type-BR-BQC-Quadplex-Circuit-Breaker-BQC220230/100112681

GE THQP two-pole breakers can be used for 240V in listed panels; something like a THQP230 in a listed GE Q-line panelboard works great for running something like a 240V 30A welder. The panelboard has to be listed for such use for it to work.

"Grounding" is an interesting topic. IIRC, NEC allows you to try driving grounding rods into soil twice--and then to say "aw, screw it" if you can't get a good ground.
Click to expand...

Grounding is a black art. Here at $dayjob we have on the order of 60 or more 20-foot electrodes, home-runned and cadwelded to bus bar with an insulated 'signal' ground and a bare 'safety ground.' Our ground conductivity here is horrible, but with the electrode field that we have the ground resistance measures at less than 0.1 ohm.
 
That's what I would consider a normal 2-pole breaker. What I was thinking of was these. A double single-pole breaker. Totally unusable for 240V 2-pole service.

There is a "4 in 1" variant that allows for 2-pole loads like this. I suspect that some inspectors will frown mightily at those, however.
 
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Chuck(G) said:
That's what I would consider a normal 2-pole breaker. What I was thinking of was these. A double single-pole breaker. Totally unusable for 240V 2-pole service.

There is a "4 in 1" variant that allows for 2-pole loads like this. I suspect that some inspectors will frown mightily at those, however.
Click to expand...

Pictures are worth a thousand words. The dual single-pole you list first I would agree about not being suitable for 240V loads; it's a bit different design than the GE THQP packaging, which does allow 240V usage. The second one is very similar to the Eaton example I used, and, since it is UL Listed, as long as it is used in its 'listed' panel the AHJ should be fine with it.
 
Chuck(G) said:
That's what I would consider a normal 2-pole breaker. What I was thinking of was these. A double single-pole breaker. Totally unusable for 240V 2-pole service.
Click to expand...

That's one type of tandem breaker (now that I know what they're called) that's present. The other type has the levers spaced along the length of the breaker, not side by side.

Fortunately, neither type is being used for 240V service.
 
When you're doing all of this, you should give a thought to load balancing--i.e., positioning wires and breakers so that one phase isn't typically loaded much more than the other--otherwise you may see more "sag" on one side of the line.
 
That's a good idea, Chuck. However, I quit smoking last night and am coming up on 21 hours, so I think it may be wise to give it a day or two before making any plans more complex than tying my own shoelaces.
 
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