240V lighting??????

[fflintstone]

Why would you want to wire 240V to lights? There's so much 120V commodity-grade stuff that's cheap and plentiful, and you aren't drawing enough current to make the wire size matter. A 120V/15A circuit will power a lot of fluorescent bulbs. Just because you can run these ballasts at 240V doesn't mean that you should.

If you're worried about the ballast's efficiency, I suggest you look around for another 120V-only ballast with a higher efficiency rating.

I hope that I will be able to die in this house so I am in it for the long haul. I found some cheap 4-lamp troffers, I found some cheap ballasts, and it will cost less than a new commodity light fixture. If wiring the lights in 240V will save me a buck or two a month over the rest of my life then it may be worth the small hassle. What I need to do is figure out how often I would use all 3000W of fluorescent light I plan to put in. figure out the kwh per month, the cost @ 120V. Then, if the ballasts are say 7% more efficient @ 240V then I could figure my savings.

 

[fefarms]

This seams like a great way to wire them if going the 240V route.
Do you have any info on the 2 pole lighting contactor you used?

I bought them used, from ebay. I like mechanically held contactors to avoid the hum of an electrically held relay. I used momentary up/down switches for on/off to provide the pulse control for the contactors.

You are looking for 20 or more amps at 240 plus volts. If I were ebay shopping today I'd consider this listing a good example:

http://cgi.ebay.com/Cutler-Hammer-2...831?pt=LH_DefaultDomain_0&hash=item4ce93b18ef

 

[Falcon67]

Well, for us guys on a budget, 250' of 14-2 is about $46 and 250' of 12-2 is $71, so if I could wire a 20x40 bay with T8 120/240 lights and use 14-2 because of the lower current, I'd save enough to pay for 10 studs. Little stuff adds up when you are trying to squeeze the dollar bills.

 

[mrb]

Well, for us guys on a budget, 250' of 14-2 is about $46 and 250' of 12-2 is $71, so if I could wire a 20x40 bay with T8 120/240 lights and use 14-2 because of the lower current, I'd save enough to pay for 10 studs. Little stuff adds up when you are trying to squeeze the dollar bills.

yeah but youll spend that $30 saved in 2P breaker and DP switches....

 

[Falcon67]

yeah but youll spend that $30 saved in 2P breaker and DP switches....

Fine - be right, balloon buster.

 

[walrus]

I buy quiet a bit of lighting and i don't think i have ever seen 240 volt lighting ( this would be lighting without a neutral.

I have seen tons of 120 volt
I have seen tons of 277 volt ( 1 leg of 460 with w neutral)
I have seen tons of multi tap or universal ballast ( all that need a neutral)

But never 240 volt. Can someone list a link to a cut sheet?

Never seen a Metal Halide ballast that didn't have 240 and no they don't need a neutral. I can't imagine a multitap without a 240 volt option

 

[Norcal]

Never seen a Metal Halide ballast that didn't have 240 and no they don't need a neutral. I can't imagine a multitap without a 240 volt option

Quite common for HID fixtures to be single voltage, rather then a multi-tap.When the fixtures were ordered for the job they could be just for the intended voltage, no need to pay for multi-tap.

 

[walrus]

Quite common for HID fixtures to be single voltage, rather then a multi-tap.When the fixtures were ordered for the job they could be just for the intended voltage, no need to pay for multi-tap.

I suppose if you are changing a bunch at a single location, I do service on multiple locations so Multitap it it is. One ballast in the truck for a certain voltage lamp. Still never seen a multitap that didn't have a 240 v option

 

[Charles (in GA)]

I suppose if you are changing a bunch at a single location, I do service on multiple locations so Multitap it it is. One ballast in the truck for a certain voltage lamp. Still never seen a multitap that didn't have a 240 v option

You are correct, the mult-tap is going to have all the options. I have 120v only ballast, as they were original installations in a Wal-Mart or Sam's Club, and were removed for fluorescent installation.

For service, it only makes sense to have multi-taps, but spec'ing a new job, its cheaper to go with single voltage ballasts.

Charles

 

[fflintstone]

well it is all a moot point now. the troffers were 3 lamp and not 4 so I did not purchase them.

 

[Norcal]

I suppose if you are changing a bunch at a single location, I do service on multiple locations so Multitap it it is. One ballast in the truck for a certain voltage lamp. Still never seen a multitap that didn't have a 240 v option

There is a tri-volt ballast made for the Canadian market, 208 & 240V is not permitted by the CEC for lighting, 120/277/347V.

 

[walrus]

There is a tri-volt ballast made for the Canadian market, 208 & 240V is not permitted by the CEC for lighting, 120/277/347V.

347 volt?, Canada has some weird stuff. New Brunswick and Quebec are pretty close but getting my service truck over the border would be a *****

 

[hillbilly1]

There is a tri-volt ballast made for the Canadian market, 208 & 240V is not permitted by the CEC for lighting, 120/277/347V.

Yeah, they will not allow the screw shell of the lampholder to be "live". With the states, the screwshell is connected to a "hot" wire when used with 208/240/480.

 

[Norcal]

347 volt?, Canada has some weird stuff. New Brunswick and Quebec are pretty close but getting my service truck over the border would be a *****

600Y/347V is a common Canadian voltage, 480Y/277 is not common...

 

[PassnThru]

well it is all a moot point now. the troffers were 3 lamp and not 4 so I did not purchase them.

It's hardly a moot point - you have started a discussion that will outlive your original question. That's the way it works sometimes.

 

[fflintstone]

It's hardly a moot point - you have started a discussion that will outlive your original question. That's the way it works sometimes.

It is a moot point for me, I know I can do it if I want; I’m not going do it because I don’t want to do it. I have not really looked into the efficiencies of 240V but since I’m not going to do it, it does not mater. It think I will go preorder CARS TOON DVD for my kid right now. I think it is a better use of my time than reading about voltage in Canada AY!

 

[Falcon67]

347 volt?, Canada has some weird stuff. New Brunswick and Quebec are pretty close but getting my service truck over the border would be a *****

I think 347 is just a metric 220V. Like converting km to miles. Or furlongs per fortnight.

 

[ishiboo]

They're probably universal ballasts which will run on foreign Live and Neutral 240v not US Live and Live 220v.

There is no difference. +120v on hot and -120v on neutral is the same as 240v on hot and 0v on neutral.

Reduced shock hazard probably. 110v ain't no biggie for most folks but 220v will get your attention



Charles,

Does this apply to all universal voltage stuff or just ballasts? I always run 90-2xx stuff on 110v in the States just to be safe. Have had a few occasions where it would've been easier to use 220v but I didn't want to risk it.

Either will kill you pretty easily, there is not a substantial difference between the two. It's likely so you don't get confused with bulbs, wiring, etc. versus an actual safety issue.

This applies to anything with the rating. If it's in the "allowed" range there is no reason "just to be safe" - already done for you.

Just a point of clarification, I'm not totally sure what opposing phases are, but it probably means the two line wires carry two sinusoids that are inverted in polarity and therefore look to be 180 degrees out of phase on a time base. It's called a three wire service and for some strange reason is referred to as single phase although the inverted polarity essentially creates two phases. The neutral is connected to the center tap of the transformer and is tied to the Earth's potential, around 0 v. I do not understand the neutral to carry an opposing phase, rather the neutral, being grounded and serving as a return path for the current, carries the same phase as the phase leg it completes the circuit with.

Since the service neutral carries back to the generation equipment the current flowing on both phase legs for circuits completed through those phase legs it only carries the unbalanced load of those two phase legs as the opposing polarity sinusoids destructively cancel each other out.

Again, the US does not run on 110 v. If you put your voltmeter on your service and you see 110v there is probably a problem.

It's single phase, both waves hit 0 at the same point. Three-phase service is completely different - there are three different waveforms which never all meet "0" at the same time. So single phase is correctly called single phase, not two phase; and three phase service has three distinct phases. You can't make three-phase by adding 1 wire to single-phase service

Neutral is connected to ground in most systems only at the circuit breaker. In a 240v wiring, you do not connect to the neutral bus, but instead both are connected to the two "hot" circuits. If there is a neutral wire present in the circuit (and there may need to be by NEC, not sure?) it is unused, and you use red/black for the two different "hots".

For the OP's question - there is not likely a substantial difference unless you have lots of lights or extremely long runs. I would run 120 to "standardize" unless you are getting a great deal on 240v-only stuffs. A different case would be in a shop large enough to have several thousand watts of metal halide lights or similar.

 

[MrMark]

This is not right. At all.

http://books.google.com/books?id=dZ...e wire residential service two phase?&f=false

 

[ishiboo]

This is not right. At all.

http://books.google.com/books?id=dZ...e wire residential service two phase?&f=false

You can argue semantics all you wish, but the reason its called "single phase" and its not "incorrect" is because they meet at 0. Three-phase does not.

In electrical engineering, single-phase electric power refers to the distribution of alternating current electric power using a system in which all the voltages of the supply vary in unison.

Three-wire, 120/240 volt single phase power used in the United States and Canada is sometimes incorrectly called "two-phase". The proper term is split phase or 3-wire single-phase. The two live outputs of a 3-wire single phase transformer secondary winding are properly called "legs".

 

[MrMark]

There are definitely two phases, A and B, 180 degrees apart. If they weren't two phases you wouldn't get more than 120 volts. I'm more concerned with your statement:


"Neutral is connected to ground in most systems only at the circuit breaker."

This is off the wall.

 

[ishiboo]

There are definitely two phases, A and B, 180 degrees apart. If they weren't two phases you wouldn't get more than 120 volts. I'm more concerned with your statement:


"Neutral is connected to ground in most systems only at the circuit breaker."

This is off the wall.

Absolutely there is a 180 degree phase difference, as the voltages are inverse. But in a single-phase system, each leg meets at 0 at the same point - they're always equidistant from zero. In three-phase, this is not the case. As I said before, that's why the world of electricity calls it single phase, like it or not

That was supposed to read the breaker box/main panel/etc, not circuit breaker... I'll correct. Obviously neither ground nor neutral are present at the circuit breaker (except in GFI breakers, where neutral appears) The point was they are tied together at one point, not multiple points, for most common installations.

 

[hillbilly1]

Absolutely there is a 180 degree phase difference, as the voltages are inverse. But in a single-phase system, each leg meets at 0 at the same point - they're always equidistant from zero. In three-phase, this is not the case. As I said before, that's why the world of electricity calls it single phase, like it or not

This is correct.

 

[MrMark]

I have no idea why you think that two waveforms sharing a zero crossing is somehow meaningful. So what? They are just as "out of phase" whether they are 1 degree off, 10 degrees off, or 180 degrees off. You are arbitrarily deciding that 180 degree phase separation is somehow special because it has a shared zero crossing and therefore cannot be two phases. I have news for you and that is if you look at the signal on an O scope, there are two phases.

If you take two wires of the same phase and connect them across a load, what do you get? Please answer.

The answer to that question should tell you something.

Well, if the world of electricity calls it that, then the world of electricity is wrong, it is a two phase system and I know at least one electrical engineer that will testify to that. I'm sure there is some crazy historical anomoly/explanation for calling it single phase.


You are wrong on your second paragraph as well. Neutral connected to the center tap of the transformer and is tied to ground at the transformer - that is why there exists 120 volts in the system between one phase and neutral. The neutral where it enters the service at the house is also earthed to stabilize the neutral voltage at around ZERO. Otherwise the system would float. Accordingly, there are at least two points in the three wire system where the neutral is connected to the earth for stabilization. Now, you may have been just referring to the service entrance and ignoring the overall system and if so then I did not understand.

 

[MrMark]

This is correct.

This is wrong.

 

[mrb]

there is a two phase system which is mostly phased out although it pops up from time to time (google Scott-T transformer). If you look at how transfomers are configured, a three phase transformer has three seperate windings, connected in a delta or wye fashion. A single phase transformer only has one winding, center tapped for 120/240v split phase service, hence the term single phase. A true two phase system actually has two seperate sets of windings, with a phase angle 90deg apart.

 

[MrMark]

All that is interesting, but the two waveforms are still of different phases. Split phase? What is that? Sounds like two phase to me. Two sets of windings? OK, that's fine, but that doesn't mean you can't product two phases with a single set of windings. I have a feeling that the term single phase came about (incorrectly) just based on the number of windings in the transformer or even more likely to distinguish it (incorrectly) from this two phase system. As I suspected, a historical anomoly.

What do you get when you put a load across two wires of the same phase and same amplitude?

Your answer, and I know you kniow it, will prove that there are two phases.

 

[mrb]

All that is interesting, but the two waveforms are still of different phases. Split phase? What is that? Sounds like two phase to me. Two sets of windings? OK, that's fine, but that doesn't mean you can't product two phases with a single set of windings. I have a feeling that the term single phase came about (incorrectly) just based on the number of windings in the transformer or even more likely to distinguish it (incorrectly) from this two phase system. As I suspected, a historical anomoly.

What do you get when you put a load across two wires of the same phase and same amplitude?

Your answer, and I know you kniow it, will prove that there are two phases.

with a single phase power source (split phase is the electrican term (i usually dont use it) for a center tapped single phase supply ie: 120/240), there is only one phase -the voltages vary together whereas in a three phase supply the voltages change sequentially one after the other. Single phase really is single phase...

 

[MrMark]

Apparently, I'm not the only one that has a problem with this.

And the answer to my question (what voltage do you get when you put a load across two wires having equal amplitude and phase) is ZERO (no potential difference) if they are the same phase and we know that is not true on a "split phase" system. On a "split phase" we see 240 Volts RMS across the two "phase" wires because they are 180 degrees out of phase. To me, when signals are 180 degrees out of phase or any number of degrees out of phase with each other we have two phases, no matter how we got there.

http://forums.jlconline.com/forums/showthread.php?t=29747

This is not me on jlconline BTW.


I will continue to call it two phase, because that is what it is. You seem to be going back to the supply now. Stating that it is a single phase supply. Well, that may be true but I still see two phase shifted waveforms (inverted waveforms) created on the transformer end. That is two phases to me.

 

[cnc-me]

Single phase one wave.
Three phase 3 waves.
Three phase would actually require 6 wires plus neutral,
if weren't for the fact that each phase returns through the other.
So you only need 3 wires plus neutral. (actually you don't need a neutral)
Single phase is like a single cylinder engine only fires once in 360 degrees
three phase fires every 120 degrees or 3 times every 360 degrees.

 

[hillbilly1]

A single phase service consists of ONE transformer, center tapped (we are not talking about using single phase of a three phase service) The transformer puts out 240 volts with a tap at the center of the windings, splitting that voltage into 120 volts per halve. Search the electricians forums, and you will find this out.

 

[MrMark]

A single phase service consists of ONE transformer, center tapped (we are not talking about using single phase of a three phase service) The transformer puts out 240 volts with a tap at the center of the windings, splitting that voltage into 120 volts per halve. Search the electricians forums, and you will find this out.

Obviously, you know it all and have not bothered to read or understand a thing written above. What you posted is well known. I obviously am well aware of the setup and how it operates if you took the time to read you would well see that. I am not interested in what electricians call something.

Answer the question presented that everyone ignores and explain how two allegedly non-phase shifted waveforms result in additive voltage levels. Inverted waveforms are phase shifted whether someone calls it single phase or not. I can obtain as many phases as I want at the end of a single phase transmission system. What do you think a phase converter does.

If it's only single phase then electricians better stop calling it phase A and phase B at the panel.

 

[Stuart in MN]

There is some cutting and pasting from Wikipedia here since it's quicker, and it says what I'd say anyway:

Single phase electric power refers to the distribution of alternating current electric power using a system in which all the voltages of the supply vary in unison (180 degrees out of phase with each other.)

In contrast, in a three-phase system, the currents in each conductor reach their peak instantaneous values sequentially, not simultaneously; in each cycle of the power frequency, first one, then the second, then the third current reaches its maximum value. (The waveforms of the three supply conductors are 120 degrees out of phase with each other.)

Two phase electrical power was an early 20th century polyphase alternating current electric power distribution system. Two circuits were used, with voltage phases differing by 90 degrees. This is similar to three phase power in that the voltages don't vary in unison.

A polyphase system must provide a defined direction of phase rotation, so mirror image voltages do not count towards the phase order. A 3-wire system with two phase conductors 180 degrees apart is still only single phase. Such systems are sometimes described as split phase.

 

[MrMark]

A polyphase system must provide a defined direction of phase rotation, so mirror image voltages do not count towards the phase order. A 3-wire system with two phase conductors 180 degrees apart is still only single phase. Such systems are sometimes described as split phase.

This is the only interesting part to me. This just tells me that it is purely definitional. "Mirror image voltages do not count towards the phase order."

Why not?

All this tells me is what has been posted above that the focus is on the generator that only has one winding; therefore only one phase. I prefer to focus on the distribution end and that transformer setup "split phase" creates two distinct phases.

Again, the question is outstanding and not yet answered or attempted to be answered.

How do you get potential difference between two waveforms of the same phase and amplitude?

 

[ishiboo]

This is the only interesting part to me. This just tells me that it is purely definitional. "Mirror image voltages do not count towards the phase order."

Why not?

All this tells me is what has been posted above that the focus is on the generator that only has one winding; therefore only one phase. I prefer to focus on the distribution end and that transformer setup "split phase" creates two distinct phases.

Again, the question is outstanding and not yet answered or attempted to be answered.

How do you get potential difference between two waveforms of the same phase and amplitude?

Phase in waves is the fraction of a wave cycle which has elapsed relative to an arbitrary point.

Amplitude is the magnitude of change in the oscillating variable with each oscillation within an oscillating system.

As I said before, at any point in time single-phase waveforms are equidistant from "zero". So the phase is the same, the fraction is the same.

The amplitude is the magnitude of change... the same value even though it's in the opposite direction!

Again, you can argue semantics all day... but you're one of few in the world who wishes to call it "two phase" instead of "single phase"... I see your point, but again the naming difference is really to differentiate between the differences between the two systems.

The actual voltage, of course, nobody is arguing is the difference between the two at any point in time. (There is no RMS when looking at a single point in time)

 

[Stuart in MN]

This is the only interesting part to me. This just tells me that it is purely definitional. "Mirror image voltages do not count towards the phase order."

Why not?

Mirror image waveforms that are 180 degrees out of phase with each other won't contribute to phase rotation.

How do you get potential difference between two waveforms of the same phase and amplitude?

You don't. You get a potential difference between two waveforms that are not in phase with each other, whether that's 180 degrees, 120 degrees, or 90 degrees.

 

[hillbilly1]

Obviously, you know it all and have not bothered to read or understand a thing written above. What you posted is well known. I obviously am well aware of the setup and how it operates if you took the time to read you would well see that. I am not interested in what electricians call something.

Answer the question presented that everyone ignores and explain how two allegedly non-phase shifted waveforms result in additive voltage levels. Inverted waveforms are phase shifted whether someone calls it single phase or not. I can obtain as many phases as I want at the end of a single phase transmission system. What do you think a phase converter does.

If it's only single phase then electricians better stop calling it phase A and phase B at the panel.

I give up......

 

[MrMark]

Mirror image waveforms that are 180 degrees out of phase with each other won't contribute to phase rotation.



You don't. You get a potential difference between two waveforms that are not in phase with each other, whether that's 180 degrees, 120 degrees, or 90 degrees.

Exactly. You have won the prize. You have just proved that it is a two phase system, no matter what it's called at the generator.

 

[W_A_Watson_II]

Lets try some math?

First the peak voltage for a 120VAC sine wave is actually 169.7V. Alternating current, or AC, is constantly changing direction and intensity. If you could periodically sample the voltage at sequential intervals in one cycle, you would find that in a 120V system the instantaneous voltage varies between -169.7V and +169.7V. Without doing any actual math, it turns out that the RMS value of a sine wave is approximately 0.707 times the peak value

In a single phase center tap application like is found in US Homes, the following two equations represent the voltage of each Leg:
Leg 1 Voltage = L1(t) = +169.7 * sin(120PI(t) + 0)
Leg 2 Voltage = L1(t) = -169.7 * sin(120PI(t) + 0)

At t=1/240, or 1/4 way through a cycle, the peek voltage you would get:
Leg 1 Voltage = L1(1/240) = +169.7 * sin(120PI(1/240) + 0) = +169.7
Leg 2 Voltage = L1(1/240) = -169.7 * sin(120PI(1/240) + 0) = -169.7

The differential between the Legs is now 339.4 Volts. Note I said differential, not the sum. Applying the RMS, the voltage between the two Legs is 240V.


Now is we looked at a two phase system with the sine waves perfectly out of sinc we would get:

Leg 1 Voltage = L1(t) = +169.7 * sin(120PI(t) + 0)
Leg 2 Voltage = L1(t) = -169.7 * sin(120PI(t) + PI)

At t=1/240, or 1/4 way through a cycle, the peek voltage you would get:
Leg 1 Voltage = L1(1/240) = +169.7 * sin(120PI(1/240) + 0) = +169.7
Leg 2 Voltage = L1(1/240) = -169.7 * sin(120PI(1/240) + PI) = +169.7

The differential between the Legs is now 0 Volts. Note I said differential, not the sum.

I believe I have all the math correct, it's been a few (many) years since I've done this, but there you go. Oh the reason the L2 voltage is a Negative is because of the transformer and the center tap.

Hope this helps.

 

[rabidsquirrel]

Exactly. You have won the prize. You have just proved that it is a two phase system, no matter what it's called at the generator.

Than what is a two phase 5 wire system to you?