ECN Forum Forums General Topics of the Trade General Discussion Area Single phase and what you call it.

This is pretty interesting for me, my language is Norwegian, and I try to understand, and does often have to guess from wht the rest of the description is about.

For a single phase circuit we deem both conductors to be live, and we always use what I call a 2 pole circuit breaker.
(At least to reasons for the double or 2 pole breakers, the neutral may carry enough current to make a voltage drop in the system, and many older houses as the one I live in has no Neutral at all. pretty equal to your delta 208 system, just cut the mid tap on one side of the delta, and rise the voltage to 230V we have 3 live wires in to our house. 230 between each of them, approx 130 to ground depending on no faults anywhere because the supply has no ground.)

A 2 way switch would for me be a switch where you connect either on or another

pictures of 2 pole switch and 2 way (2 pole) switch as i would have translated it

Single Phase 2 Wire -vs- Two Phase 3 & 4 Wire:

1 Ph. 2 Wire is either DC (series, parallel, etc.) or AC (induction etc.)
Two conductors - 120v, 208v or 240v, will make this work.

2 Ph. 3 & 4 Wire comes in AC only.

Scott 35.

Okay. My personal answer is in favor of the "too pedantic" explanation.

It may be "wrong" given what we typically use the terms to mean, but, language-wise, outside of traditional application, I believe it to be correct.

We call 3-phase electricity "3 phase" because the three hots are different phases, 120 degrees apart. We automatically assume them to be 120°, and in terms of electrical distribution they're pretty much guaranteed to be, but that is *not* part of the definition, the English definition that is, of either "three" or "phase." The phrase "three-phase," purely in English, does not specify what phases they are, only that there are three of them.

The two hots in a 240V single-phase center-tapped service are... essentially 180 degrees away from each other. They weren't generated that way, for sure, and you could never really call the primary side of the pole transformer "two phase," but after that, with reference to ground/neutral, we do, in fact, see two hots that appear at different phases.

"Two phase" with regards to electrical distribution is likely to imply a 90° separation, but "two phase" taken purely in English could very well, and accurately, describe the services we have here in the US...


... so... misuse of the term may very well indicate to me that whoever I'm talking to doesn't have much (or any) background in electrical distribution, and I may thus question the rest of whatever they are saying, but no, it doesn't bother me any.


... one that DOES bug me though... I work with some people who are entirely on the electronics repair side of things -- they're quite adept at getting the inner workings of appliances to do what they are supposed to, but I'm so sick of hearing 110, 115, 117, 125, 130, 210, 220, and 230. I know there is some tolerance, and I could even be coaxed into accepting some of these "incorrect" voltages if the people spouting them wouldn't ALSO ask me things like, "is this 110 or 210?" . . . If I agree to accept your assertion that your line voltage is 110, then twice it better darn well be 220. If you've got 210, then one leg must be 105, which is just absurd. On this one I try to convince myself they're rounding up from 208, but then I hear 120 and 220 and steam starts coming out of my ears.

Seen from Norway, I have the same ideas about it, and here the formal service delivered are sold as single phase, or 3-phase. (2 or 3/4 wires (not always any N)



Again this is depending of (level of) knowledge, ways of simplifying, a mix of older and newer standards of nominal voltages, and more or less accurate readings of a voltmeter.

Here in Norway, the nominal voltage is 230V +/- 5 or 10 % depending on where you live. 80 years ago or so, it was 220.
The 3-phase systems was usually 3 wire 230V with no neutral. (What I have her in my house)
The new standard are now 400 with neutral, and then 230 between each leg and N. In some regions they have 230V 3-phase where the transformer center Y is grounded, but the supply are still 3 wires.

Most people around me still talks about 220 in Norway (or Europe), and 110 in America (when they are talking about USA/Canada)

We are never talking about the frequencies, and today our frequency are stable 50 Hz here. I have read about the 1950-ies where the load was so high that the entire grid slowed down to 47 on day time and they compensated during the night to get the clocks right.

The next coming up is old equipment on new nominal voltages, you got e.g. radios where you could choose 110,125, 220, 240, 250V and people asks does it matter? what shall I do??? My Answer is always, try if it works OK on the next step over, and if that is OK.. it s OK.

The distinction between supply voltage and nameplate rating voltage does confuse things further, and I believe that distinction is only made in the US. In Europe an appliance with a nameplate rating of 230 V AC is supposed to work on a supply anywhere within the nominal 230 V +/- 10%.

On the other hand I have to agree it becomes quite obvious that someone has limited grasp of electrical theory when they talk about both 230 and 380 V in the same sentence (or 220 and 400) while both the pre-harmonised and current supply voltages are obviously linked by the factor sqrt(3). The different voltages frequently mentioned in Europe have historical reasons - by the 1970s almost all countries had standardised to 220/380 V 50 Hz while the UK had 240/415 V 50 Hz. In the 1980s the decision was made to harmonise all European supplys to 230/400 V and most countries adopted that standard during the late 1980s and early 1990s, either by actually adjusting the voltage on the MV side or by just making sure the supply voltage wouldn't exceed the new limits (the first approach results in supply voltages in the 228-235 V range or pretty close to 230 V while the latter gives something closer to the old supply voltage).

it drives me crazy, i don't trust anyone that calls it that with electrical work.

its signle phase

also calling a "leg" a "phase" drives me crazy, it takes two legs to create a phase, a phase is not a leg, a leg is not a phase and yes ground is a leg in a grounded system