120V Plug and 208V Outlet
Before I discovered about the lack of 120V wall outlets, I was just going to use an APC SmartUPS 750. Is there some way to just adapt from its NEMA 5-20 plug to the 208V outlet on the wall? Existing wiring in the server room has a 208V circular outlet. At the moment I don't know if it is 20A or 30A so please include both scenarios.
In order to stick with the current environment, we have to use APC. However everything the APC seems to offer in 208V input seems to be very expensive, plus I would have to step it down for the devices which are all NEMA 5-15 120V.
In order to stick with the current environment, we have to use APC. However everything the APC seems to offer in 208V input seems to be very expensive, plus I would have to step it down for the devices which are all NEMA 5-15 120V.
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I don't think any of those match. It's an L type plug. So a three prong locking plug. I just don't know if it's 20A or 30A. I would have to go back and check.
Be sure you mean 208 Volts and not 240 Volts. 208V is a 3 phase arrangement and need a special UPS designed for 208 Volts.
Almost any UPS will have a switch to change between 120 V and 240 Volts.
A 240 Volt socket has a round ground, vertical and horizontal slots for the matching 240 Volt plug.
Almost any UPS will have a switch to change between 120 V and 240 Volts.
A 240 Volt socket has a round ground, vertical and horizontal slots for the matching 240 Volt plug.
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I would not try that as it could easily invalidate your insurance
I concur with John. Unless you are qualified, probably better not to mess with mains power. If anything goes wrong, even through no fault of your own, you could find yourself in a whole world of trouble really quickly.
If it is a 3 pin plug it will have 2 lives plus earth, no neutral unfortunately. Needs either needs a transformer or an electrician.
Not many UPSs that have a voltage switch.
Not many UPSs that have a voltage switch.
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So the answer is basically either "you can't do it" or "you can do it, but don't". Will speak to an electrician about what can be done with the plug.
Most homes are wired with single-phase that uses one ac voltage delivered over two hot wires separated from each other by 180 electrical degrees, and one neutral wire. The voltage across the two hot wires measures 240VAC (for your oven or dryer) and across any hot to neutral measures 120VAC (for everything else).
Most commercial businesses are wired with 3-phase that consists of three ac voltages separated from each other by 120 electrical degrees, or by a third of a cycle. These systems deliver power over three hot wires where the voltage across any two hot wires measures 208VAC.
Another way to look at 3-phase power is as a combination of three single-phase circuits that deliver power in a way that it never falls to zero, meaning that the load is the same at any instant (the concept is easier to grasp when you look at the waveform).
There are two types of circuits used to maintain equal load across the three hot wires in a 3-phase system—Delta and Wye. The Delta configuration has the three phases connected like a triangle, whereas the Wye (or “star”) configuration has all three loads connected at a single neutral point.
Delta systems have four wires—three hot and one ground. Wye systems have five wires—three hot, one neutral and one ground. While both Delta and Wye systems measure 208VAC between any two hot wires, Wye systems also measure 120VAC between any hot wire and neutral. In other words, it’s the neutral wire of the Wye system that allows for providing two different voltages and powering both 3-phase and single-phase devices in the data center.
See: https://www.belden.com/blog/data-centers/3-phase-power-wye-it-matters
Most commercial businesses are wired with 3-phase that consists of three ac voltages separated from each other by 120 electrical degrees, or by a third of a cycle. These systems deliver power over three hot wires where the voltage across any two hot wires measures 208VAC.
Another way to look at 3-phase power is as a combination of three single-phase circuits that deliver power in a way that it never falls to zero, meaning that the load is the same at any instant (the concept is easier to grasp when you look at the waveform).
There are two types of circuits used to maintain equal load across the three hot wires in a 3-phase system—Delta and Wye. The Delta configuration has the three phases connected like a triangle, whereas the Wye (or “star”) configuration has all three loads connected at a single neutral point.
Delta systems have four wires—three hot and one ground. Wye systems have five wires—three hot, one neutral and one ground. While both Delta and Wye systems measure 208VAC between any two hot wires, Wye systems also measure 120VAC between any hot wire and neutral. In other words, it’s the neutral wire of the Wye system that allows for providing two different voltages and powering both 3-phase and single-phase devices in the data center.
See: https://www.belden.com/blog/data-centers/3-phase-power-wye-it-matters
Brian, any chance of getting the electrician to upload a photo of the socket with face plate removed? Wold be worth a lot more than points at EE to know if there's a choccy-block mounted on the back-housing to pass the unused live and neutral through to the next socket or if that's added in a second box hidden behind a blank faceplate.
Will make a difference to how long it take him too
Will make a difference to how long it take him too
...Most homes are wired with single-phase that uses one ac voltage delivered over two hot wires separated from each other by 180 electrical degrees...
Where in the world that? It's physically possible but I know of no country that uses two (or four) phases in their electric supply.
Where in the world that? It's physically possible but I know of no country that uses two (or four) phases in their electric supply.
My house is single phase 240V
The company I worked for a long time ago sold 208 V ranges (stoves). The ranges had to go with the appropriate household supply and were not interchangeable
The company I worked for a long time ago sold 208 V ranges (stoves). The ranges had to go with the appropriate household supply and were not interchangeable
Hmm, thought you (John-Thinkpads) were in 120V land USA/Canada.
I'm in UK; traditionally 240V but dropped to 220v gradually to reduce death by electrocution and to meet EU standards. Played about with 120v when a builder left his transformer behind, enough to know that the average dual-PSU server runs happily with 110V on one PSU and 220V on the other.
I'm in UK; traditionally 240V but dropped to 220v gradually to reduce death by electrocution and to meet EU standards. Played about with 120v when a builder left his transformer behind, enough to know that the average dual-PSU server runs happily with 110V on one PSU and 220V on the other.
I am in Canada and lived in Northeastern USA a while back. In all my homes.
1. Two voltage wires 120 V each.
2. One neutral wire, bonded to earth ground.
3. Two wires can add to provide 240 V and so that is single phase (must be for two phases to double when combined).
1. Two voltage wires 120 V each.
2. One neutral wire, bonded to earth ground.
3. Two wires can add to provide 240 V and so that is single phase (must be for two phases to double when combined).
Andy, you need to understand AC . Check the link I provided, it will show you how it works. Home electric panels usually will have two power legs (lines) feeding them and a neutral Line that may also be tied to ground. You will see two columns of breakers (or fuses in older homes) one column has a solid bar under it that connect to one power leg and the other column has a solid bar under it that connects to the other leg. The neutral and ground lines have no power. Each input leg carries 120volts -- 180 degrees out of phase with each other. So, when one line is at its peak positive 120 volts, the other is at its peak negative 120 volts. The difference between the two peaks is 240 volts. Just connect them to a dual trace scope, you can see it.
If the two were the same phase, then holding a meter between the two power lines would show 0 (zero) volts, because each leg would be at its high or low at the same time making the difference 0. There would be no way to get 240 volts! All power legs in the USA are 120 volts to neutral. The way you get to 240 volts is to have the AC sine waves 180 degrees out of sync between two power legs. Then the voltage measure between the two power legs is 240 volts.
In 208 volt 3 phase the legs are 120 degrees out of sync. So when you measure between any two power legs, you get 208 volts, but if you measure any single leg to neutral you get 120 volts. In this case when one leg is at its high point the other legs are 50% negative.
Again, take a look at the charts in the link I provided,
If the two were the same phase, then holding a meter between the two power lines would show 0 (zero) volts, because each leg would be at its high or low at the same time making the difference 0. There would be no way to get 240 volts! All power legs in the USA are 120 volts to neutral. The way you get to 240 volts is to have the AC sine waves 180 degrees out of sync between two power legs. Then the voltage measure between the two power legs is 240 volts.
In 208 volt 3 phase the legs are 120 degrees out of sync. So when you measure between any two power legs, you get 208 volts, but if you measure any single leg to neutral you get 120 volts. In this case when one leg is at its high point the other legs are 50% negative.
Again, take a look at the charts in the link I provided,
>3. Two [120v] wires can add to provide 240 V
OMG, I hope you don't wire the plugs in your house.
OMG, I hope you don't wire the plugs in your house.
I have wired both 120 Volt and 240 Sockets. Yes, I do know what I am doing.
Canada uses 240V single phase like UK? Didn't realise that since it is so close to USA, thought they would share the same standard. It's not two 120V supplies added together though, just try measuring two phases in 240v land, you'll get this...
If that is true, it is not single phase.
Indeed not, it's what you see on the wall between two single-phase sockets in 220/240v land in case you shove two screwdrivers into adjacent sockets and hold on to them.
John, my comment was aimed at andy. He does not understand how AC works. BTW knowing how to connect the wires does not mean you know how it works. In the USA all power lines into a home or business are 120 volts AC, when measured to neutral zero. AC current flows positive to negative 60 times per second. In homes with two feed lines, each is 180 degrees out of sync with the other. Meaning, at the time one is 120 positive the other is 120 negative, but neither is ever more than 120 if measured to neutral or ground.
The only way to get to 240 volts is for one side to be positive 120 at the time the other side is negative 120 (180 degrees out of sync). If both are positive at the same time the difference between them would be zero. If you use a meter and measure to neutral you will see both feeds are 120 volts. if you put you meter on two different circuits off the same side you get zero, because each is at 120 volts at the same time -- no electrical potential exists between those points. However, when the meter is connected between the power feed legs, you will see the difference between them 240 volts, (if 180 degrees out of sync) or 208 volts (if 120 degrees out of sync), or 0 volts (if 360 or 0 degrees out of sync).
Home panels are designed to keep the power legs separated, so people in general can wire a house without knowing about these things. All they know is that to get 240 volts they use a double breaker and run two power wires instead of one (usually one black and one red). What they don't have to know is that the two power wires are one from each feed line, which are 180 degrees out of sync. Some that don't understand AC think the voltage just adds together magically. If that were true, why not just use two single breakers from the same side and see what happens -- nothing, because they are the same phase.
The only way to get to 240 volts is for one side to be positive 120 at the time the other side is negative 120 (180 degrees out of sync). If both are positive at the same time the difference between them would be zero. If you use a meter and measure to neutral you will see both feeds are 120 volts. if you put you meter on two different circuits off the same side you get zero, because each is at 120 volts at the same time -- no electrical potential exists between those points. However, when the meter is connected between the power feed legs, you will see the difference between them 240 volts, (if 180 degrees out of sync) or 208 volts (if 120 degrees out of sync), or 0 volts (if 360 or 0 degrees out of sync).
Home panels are designed to keep the power legs separated, so people in general can wire a house without knowing about these things. All they know is that to get 240 volts they use a double breaker and run two power wires instead of one (usually one black and one red). What they don't have to know is that the two power wires are one from each feed line, which are 180 degrees out of sync. Some that don't understand AC think the voltage just adds together magically. If that were true, why not just use two single breakers from the same side and see what happens -- nothing, because they are the same phase.
Where are you that you get two feeds 180 degrees out of sync?
U. S. I think this might be our problem ... different countries do it differently. If you check the link I provided above, it describes the U. S, methods very simply and clearly.
USA does not have 2 phases 180 degrees apart.
check the Belden link. or provide your substantiating reference. You could be citing outside power before the transformers. I am citing in the building after the transformers. Common feeds are two feeds 180 apart or 3 feeds 120 apart.
I was referring to the feed into the building, however I seriously doubt there are many homes that have a whopping great transformer to convert 3-phase to two-phase. Obviously Brian B doesn't have one in their offices or they wouldn't have 208V sockets.
I stand corrected, apparently you do have one transformer each for residential properties, however that's still not what Brian B has in his office block.
Geez Andy, do you not open your eyes when you are outside? The transformers belong to the utility companies and are included on the utility poles or ground stations to service neighborhoods or large buildings. In general they provide 120 volt legs 180 degrees out of phase. For large buildings or complexes Data Centers delta to Y transformers provide 3 120 volt legs 120 degrees apart. You can see them by just driving around any city or neighborhood -- High on electric utility poles or in large (3 to 4 foot) green or gray metal utility boxes on the ground.
Again I say cite your sources.
This Wiki describes how local power is delivered (service drops), see especially the third paragraph Residential, North American. Where it clearly states The service drop provides the building with two 120 V lines of opposite phase,
>>> https://en.wikipedia.org/wiki/Service_drop
This describes split phase electrical power
>>> https://en.wikipedia.org/wiki/Split-phase_electric_power
And my earlier Belden link that describes 3 phase power and delta to y transformers out puts , very simply. Belden is a recognized data center electrical equipment supplier in the U.S.
>>> https://www.belden.com/blog/data-centers/3-phase-power-wye-it-matters
Again I say cite your sources.
This Wiki describes how local power is delivered (service drops), see especially the third paragraph Residential, North American. Where it clearly states The service drop provides the building with two 120 V lines of opposite phase,
>>> https://en.wikipedia.org/wiki/Service_drop
This describes split phase electrical power
>>> https://en.wikipedia.org/wiki/Split-phase_electric_power
And my earlier Belden link that describes 3 phase power and delta to y transformers out puts , very simply. Belden is a recognized data center electrical equipment supplier in the U.S.
>>> https://www.belden.com/blog/data-centers/3-phase-power-wye-it-matters
Brian B's office has 3 phases 120 degrees apart, that's why he has 208v available.
Gosh those transformers on poles look horrible, we don't have them over here.
Gosh those transformers on poles look horrible, we don't have them over here.
Yep, pretty ugly little buggers... most poles in cities are in alleys out of site from the street. But out in the suburbs, we have no alleys so the poles line the main feeder roads. Many subdivisions these days have underground wiring to the homes, but the older ones have poles behind, or aside or in front -- making it very unsightly.
This has certainly opened my mind. I know quite a lot about UPSs and PDUs (single and 3-phase) and our 415V is the same layout as your 208V but having one transformer per house just hasn't made sense to me before now. We have one big transformer for about 50 houses and hide it behind a wooden fence so it looks pretty and run a high current low voltage cable up each side of the pavement underground. Having the transformers up a pole saves on buying a plot for the communal substation.
We don't have one transformer per house. Each runs 5-20 homes.
Interesting.
Wold be pretty simple I guess to have two out of phase 120V lines feeding into a home, it would just mean a step down transformer with a center tap.
Here in Australia this in not done; houses are supplied one, two or three phases each 240V WRT to neutral, depending on how much power is required. 3 phase power outlets are less common in residences, and run 415V between phases. Some people have 3 phase in their homes for recharging electric vehicles, running large water heaters, or large welders.
Wold be pretty simple I guess to have two out of phase 120V lines feeding into a home, it would just mean a step down transformer with a center tap.
Here in Australia this in not done; houses are supplied one, two or three phases each 240V WRT to neutral, depending on how much power is required. 3 phase power outlets are less common in residences, and run 415V between phases. Some people have 3 phase in their homes for recharging electric vehicles, running large water heaters, or large welders.
I have 3 phase in my flat but only because it feeds the other flats above, there's only one phase used on each floor similar to commercial buildings. The only split-phase we use here is for builders so if they saw through their power lead they only get a 55v shock.
@ Mal If you have 240 volt legs to neutral and 415 between phases, then there is a phase shift. (likey 120 degrees apart or 3 phase)
@ andy what country do you live in? I know of none with 55v differentials. The USA has one of the lowest at 120v,
@ andy what country do you live in? I know of none with 55v differentials. The USA has one of the lowest at 120v,
This is a builder's transformer.
https://www.screwfix.com/p/portable-transformer-with-2-output-sockets-3kva/84144
https://www.screwfix.com/p/portable-transformer-with-2-output-sockets-3kva/84144
U.K. Their standard for home systems is 230 volt single phase, so the is no second leg like in the U.S. Your industrial feeds however are 230 volt 3 phase. In those locations any of the 3 hot lines will measure 230 volts to neutral and 415 volts between any two hot lines, because they are 120 degrees out of phase.
From Wikipedia, U.K. re: construction transformers..
This is an example of using two 55 volt AC lines (transformer legs) that are 180 degrees out of phase (center tapped transformer) to produce 110 volts. Either line (leg) to the center tap (or ground) will measure 55 volts. But when measured to each other they read 110 volts, due to the 180 degree phase shift.
This sort of explains why you don't understand the 180 degree and 120 degree phasing -- it does not apply in U.K. homes. However I did note, that transformers do in fact exist in your neighborhood power grid (before entering the home). But, since your voltages are 230 volts, they can serve more homes at greater distances than in the U.S. at 120 volts. So, when you are outside, keep your eyes open for them.
An interesting side note, those transformers out put 3 legs, but each home only gets one. That means if your neighbor is not on the same leg, you could measure 415 volts between hot lines in each house.
From Wikipedia, U.K. re: construction transformers..
The risk of electrical shock on construction sites can be reduced by several measures, including reduction of the normal 230 volt distribution voltage to 110 volts for electrical lighting and power tools. By using a centre-tapped transformer, each conductor of the circuit is only at 55 volts with respect to earth. This reduces the chance of dangerous electrical shock when using power tools in wet locations.[9]
This is an example of using two 55 volt AC lines (transformer legs) that are 180 degrees out of phase (center tapped transformer) to produce 110 volts. Either line (leg) to the center tap (or ground) will measure 55 volts. But when measured to each other they read 110 volts, due to the 180 degree phase shift.
This sort of explains why you don't understand the 180 degree and 120 degree phasing -- it does not apply in U.K. homes. However I did note, that transformers do in fact exist in your neighborhood power grid (before entering the home). But, since your voltages are 230 volts, they can serve more homes at greater distances than in the U.S. at 120 volts. So, when you are outside, keep your eyes open for them.
An interesting side note, those transformers out put 3 legs, but each home only gets one. That means if your neighbor is not on the same leg, you could measure 415 volts between hot lines in each house.
It was only your 180 degree split phase to each home that I didn't know about as nowhere in 220-240v land is that used. Not that that is any use to me nor is it relevant to this question since Brian B has 3 phase 120v. All the rest I have known for a long time since they teach it to us in school.
Brian's computer room is supplied with 3 phase 120v similar to our computer rooms being fed with 3 phase 230v, your offices have 3 phase supplies just like ours so 208 and 415 v are very familiar to me.
These voltages are nominal and not exact, the builder's transformer actually puts out 115v nominally as it's just a 2:1 stepdown with centre tap. The voltage varies a bit from district to district since they don't add a couple more windings on the transformer to make it exact, the phase however is identical all over the country, when phase A is at its peak in Manchester it is also at its peak in London.
It is no use me keeping my eyes out for my neighbourhood transformer since I have already told you they hide them behind a wooden fence (and call it a substation). Offices normally have a substation in the basement. You do see transformers on poles over here in the countryside just before you arrive at a village but they are not cylindrical.
>An interesting side note, those transformers out put 3 legs, but each home only gets one.
Glad I could teach you something, There is almost always 415v between adjacent properties except when they build a new house between two others; for larger buildings like the one I live in all 3 phases are supplied and it is split between floors. When a fuse blows at the substation every third house is dark although in my case it was only my floor in our building.
Brian's computer room is supplied with 3 phase 120v similar to our computer rooms being fed with 3 phase 230v, your offices have 3 phase supplies just like ours so 208 and 415 v are very familiar to me.
These voltages are nominal and not exact, the builder's transformer actually puts out 115v nominally as it's just a 2:1 stepdown with centre tap. The voltage varies a bit from district to district since they don't add a couple more windings on the transformer to make it exact, the phase however is identical all over the country, when phase A is at its peak in Manchester it is also at its peak in London.
It is no use me keeping my eyes out for my neighbourhood transformer since I have already told you they hide them behind a wooden fence (and call it a substation). Offices normally have a substation in the basement. You do see transformers on poles over here in the countryside just before you arrive at a village but they are not cylindrical.
>An interesting side note, those transformers out put 3 legs, but each home only gets one.
Glad I could teach you something, There is almost always 415v between adjacent properties except when they build a new house between two others; for larger buildings like the one I live in all 3 phases are supplied and it is split between floors. When a fuse blows at the substation every third house is dark although in my case it was only my floor in our building.
Can you identify the sockets from https://www.seldirect.com/NEMA%20Plug.html ?