bobdroege7
Illuminator
- Joined
- May 6, 2004
- Messages
- 4,409
I know that it's made 3 phase 120 degrees apart, so if you have 240 two phase power, it's 120 degrees apart, not 180.
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120 V or 240 V Mains - which voltage is better?
- Thread starter psionl0
- Start date
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- Tags
- electricity
aleCcowaN
imperfecto del subjuntivo
You should understand what polyphase is in this context before reaching any conclusion.
A 240V two phase power 120 degrees apart is the three-phase system called in Spanish "triángulo abierta" that I mentioned above. When I translate it into "open delta" -which is the right translation of the concept in the name- it seems to refer to a different thing.
Trebuchet
Penultimate Amazing
I think it's rare these days, but 208V three phase with a neutral provides a convenient 120V from each phase to the neutral. Very early in my engineering career I actually got to design a machine for that. We could eliminate the usual transformer to provide 120V for the control circuitry.
DGM
Skeptic not Atheist
That's not what he's saying. In my shop I have 10 amp and 20 amp 220v circuits that run with 14 and 12 gauge wire running small machines.
The amount of (expected) draw determines the wire size.
Dabop
Master Poster
As we dont work with these 'gauge' wires, I would have to consult google to find out what size they actually are, but I can state with 100% accuracy, and I'll support with links, that if you want the same load (stated in watts) then it will 100% guaranteed halve the current every time you double the voltage
(what is the NEC- I assume from your comment it is some kind of regulatory body in the US???)- The only NEC I have come across here makes cash registers and the like, and altho the power companies certainly have no qualms about taking my cash, I doubt they have much to do with the wiring codes...)
;-)
(what is the NEC- I assume from your comment it is some kind of regulatory body in the US???)- The only NEC I have come across here makes cash registers and the like, and altho the power companies certainly have no qualms about taking my cash, I doubt they have much to do with the wiring codes...)
;-)
Thermal
August Member
National Electrcal Code, part of National Fire Prevention code
DGM
Skeptic not Atheist
National Electric Code. It's a huge catalog of information put into the most complicated way possible.............
Dr.Sid
Philosopher
It's different .. voltage and current are 2 sides of the same coin (well, together with resistance) you can't have one without another. Gunpowder and bullet are just two things.
120V is safer for sure, but it's by no means 100% safe.
Dabop
Master Poster
12 0.0808 2.05
13 0.0720 1.83
14 0.0641 1.63
15 0.0571 1.45
OK weird yank wire sizes figured out in real measurements ie mm^2
I have heard of these 'gauge' wires but never had to deal with imperial units, even when we had feet and inches we still used fractions of an inch ^2 for cable sizes
The only 12 gauge I have ever used went boom and was good on rabbits....
13 0.0720 1.83
14 0.0641 1.63
15 0.0571 1.45
OK weird yank wire sizes figured out in real measurements ie mm^2
I have heard of these 'gauge' wires but never had to deal with imperial units, even when we had feet and inches we still used fractions of an inch ^2 for cable sizes
The only 12 gauge I have ever used went boom and was good on rabbits....
Thermal
August Member
Dabop
Master Poster
Dabop
Master Poster
Actually here it does
but thats not what you said, "14 or 12 gauge wiring is used for 120v, but the higher amp draw of 240v"
is a factually incorrect statement
240v doesnt 'draw' more amps, in your country it is used for higher wattage appliances, here it isnt- everything from my led desklamp to the 3600w hot water service is 240v
And to do the same amount of 'work' ie wattage consumed- the voltage when doubled, will halve the current- which is why we use 240vac in the first place
DGM
Skeptic not Atheist
These are not the only examples of 220v appliances used in the US.
Electric baseboard heat and A/C units along with bathroom heaters are good examples that are typically rated as 20 amp or less.
Your blanket statement is incorrect.
aleCcowaN
imperfecto del subjuntivo
Exactly: delta 208V is wye 208/sqrt(3)= 120V
but you never had needed a transformer: that's the way it's designed to be. You decided to plug it in one configuration and not the in the other.
psionl0
Skeptical about skeptics
3 live to neutral voltages each 120 degrees out of phase relative to each other is 3 phase power.
But 2 live to neutral voltages both 180 degrees out of phase relative to each other is NOT 2 phase power. Got it.
psionl0
Skeptical about skeptics
You are right if you are talking about something completely different to what I am posting.
I am referring to the power lines that run past your house and which you connect to in order to supply your house. (The 7,200 volt reference should have been a clue).
Thermal
August Member
Yes, I get that Oz is wired differently than the States, and I of course agree with the wattage calcs. Context. This is the post I responded to:
To use your phrasing, this is factually incorrect statement. The 220 supply lines in the States for the high draw appliances listed earlier are not the same gauge as the 110 lines.
ETA: calling it amp draw instead of wattage draw is just construction shorthand around these parts.
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aleCcowaN
imperfecto del subjuntivo
I add myself to the list of people boggled by that "gauge" thingy of those ethnic standards.
I declined to look for wire section. The "ampacity" of a "14 gauge" (my goodness!) is 15 Ampere in copper, so it must be between 2 and 2.5 square millimetres, if the same rules for wire life and safety are applied. If it's less than that, OMG! such wires in cardboard and match houses!
About some two-person debate: undoubtedly using 240V for the same energy consumption requires half of the current needed under 120V, but that won't make regulations any lighter regarding minimum wire section (or maximum "gauge" if you like that).
I declined to look for wire section. The "ampacity" of a "14 gauge" (my goodness!) is 15 Ampere in copper, so it must be between 2 and 2.5 square millimetres, if the same rules for wire life and safety are applied. If it's less than that, OMG! such wires in cardboard and match houses!
About some two-person debate: undoubtedly using 240V for the same energy consumption requires half of the current needed under 120V, but that won't make regulations any lighter regarding minimum wire section (or maximum "gauge" if you like that).
DGM
Skeptic not Atheist
It's really called: NFPA 70: National Electrical Code (NEC) (2017).
It changes constantly and is not cheap to keep up with.
http://www.nfpa.org/nec
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Dabop
Master Poster
3 live to neutral voltages each 120 degrees out of phase relative to each other is 3 phase power.
But 2 live to neutral voltages both 180 degrees out of phase relative to each other is NOT 2 phase power. Got it.
Shrugs- well I agree with you psion10, it was referred to as 2 phase power here when it was still used (mostly in country areas in some states)
2 phases 180 deg apart was 2 phase, 3 phases 120 deg apart is 415v/440v 3 phase, uncommon to have a dedicated motor etc using 2 of 3 phases of 240v, but common to split loads over 2 phases in large households where the current drawn was going to exceed the street line supply of 70A (older) or 100A(newer) where you could have 2 of 3 phases connected to the house to provide sufficient power (solid neutral required in the install tho)
(solid neutral is where the neutral is capable of carrying the combined total of all three phases, light or floating neutral has the same sized conductor as any single active or line conductor and a solid neural has the neutral wire is much larger than any single active conductor)