[pudge565]

Or be identified by other effective means. (See 110.15)

Chris

I disagree with you. The wording that you quoted refers to the way it is identified not the color to be used. "...shall be durably and permanently marked by an outer finish that is orange in color or by other effective means..." The "...or by other effective means is saying that the insulation covering does not have to be orange in color it can be re-identified as orange in color (if allowed by other sections of the code) but it shall be orange in color.

 

[Bob Badger]

I disagree with you.

And I disagree with your disagreement.

Other effective means could simply be tags or and other way acceptable to the AHJ.

 

[pudge565]

And I disagree with your disagreement.

Other effective means could simply be tags or and other way acceptable to the AHJ.

Duly noted. I suppose it is up to the way the AHJ interprets it.

 

[Mogie]

Ok I have a question about a high leg delta transformer. I know that phases A and C to neutral you get 120 and that phase B to neutral you get 208. I also know that between any two phases you get 240. My question is why don't you get 328 volts from phase B to either phase A or C? I believe it has to do with the was the sine waves are off from each other but am not totally sure. Does any one have a good explaination? Or maybe a diagram of the sine waves?

I know this is an old post, but I don't think anyone ever answered your question. Voltage between phases is not necessarily additive. In a delta service, A-B=240v; B-C=240v; A-C=240v. You derive 120v on A and C phase by grounding between the two 120v coils in the center. The voltage from ground to B is then as shown in oldman's diagram, resulting in a nominal voltage of approx 208 (often anywhere between 200-210).
In a 120/208 wye service, ground is derived in the center of the "Y", resulting in 120v from ground to each of the three phases, making it a more useful transformer configuration for commercial applications, where minimal motor loads are used. Voltage between phases is then calculated by 120v x 1.732 (square root of 3) = 208v nominal. Similarly, w/a 480v wye configuration, ground is established in the center of the "Y". Ground to each phase is 277v. Phase-to-phase voltage is calculated as 277x1.732 = 480v.
I hope this clears things up a little.

 

[kwired]

Drawing out a delta connection or a wye connection make your coils 120, 240,208, 277, or 480 units(mm, inches, feet, miles whatever you wish) that apply and you will find that geometric rules will define the size of what you draw. If you draw a wye with 120 long legs that are 120 degrees apart the ends will be 208 units away from each other. Now think of the units of length as a number of turns in the transformer coils and equate this to the voltage produced by that number of coils.

Same thing applies to straight lines representing single phase transformers - a tap in the center will be half the distance of the line, a tap in the center of a coil will be half the voltage to each end as the voltage is from end to end.

 

[Avanti]

Delta transformer connections

There are many types of delta transformer (TX) connections ether single phase or three phase. On a single phase transformer the most common type is the Wye high side and delta secondary side 120/240v the result. Three phase however is a different story, well we don't even need three high side (Primary or H1) phases. The open WYE/ DELTA can be used to make two 120v legs and light three phase secondary power from only two Primary phases and two Wye / Delta single phase TX's. This is a common connection for small apartment buildings for the there phase elevator load. This connection produces three phase secondary 240V power; using one TX for lighting load and the other for the power load. By tyeing the X1 of the power TX to the X3 of the lighting TX making three phases, by using a full coil on the power Tx and on half a coil on the lighting TX. The result is 120V on all the secondary legs and 240v phase to phase on all except the X3 of the power TX will be 208v to ground However; the same X3 leg phase to phase will yield 240v phase to phase. The 208V is measured phase to ground and this voltage is a result of the delta connection. I know of nothing that uses 208v volts to ground in this country or else were. The 208. is pretty much useless except on trouble shooting problems as a voltage cheek. If I have 208V to ground on the power leg I know that both Tx's are hot to the high side. Note for this discussion I used two WYE / DELTA , additive polarity transformers. This is only one type of TX hook up there are many, wye /delta , open wye / delta , closed wye/ delta, closed delta/delta; and all are 120/240v or 240/480 as all delta secondary is. Grounded Wye 120/208v, 277/480v voltage is a hole other animal.

 

[Avanti]

I have seen orange and also purple used for the high leg. All three PoCo's i have worked for 32 years put the high leg on the far right position in the meter can, C phase have you, I know the NEC has it in the middle B phase. They do this because the 3 phase delta meter is set up to meter with the high leg to the right.

 

[brian john]

There are many types of delta transformer (TX) connections ether single phase or three phase. On a single phase transformer the most common type is the Wye high side and delta secondary side 120/240v the result.

In my experience a secondary of a single phase transformer is neither delta or wye.

What do you mean by TX?

Three phase however is a different story, well we don't even need three high side (Primary or H1) phases. The open WYE/ DELTA can be used to make two 120v legs and light three phase secondary power from only two Primary phases and two Wye / Delta single phase TX's. This is a common connection for small apartment buildings for the there phase elevator load. This connection produces three phase secondary 240V power; using one TX for lighting load and the other for the power load. By tyeing the X1 of the power TX to the X3 of the lighting TX making three phases, by using a full coil on the power Tx and on half a coil on the lighting TX. The result is 120V on all the secondary legs and 240v phase to phase on all except the X3 of the power TX will be 208v to ground However; the same X3 leg phase to phase will yield 240v phase to phase. The 208V is measured phase to ground and this voltage is a result of the delta connection.

The open delta transformers I have seen if the 120 VAC is derived on the secondary 3 phase was not available for motor loads? Can you post a link or diagram?

Are you referring to a center tapped winding for the 120 VAC?

The 208V is measured phase to ground and this voltage is a result of the delta connection. I know of nothing that uses 208v volts to ground in this country or else were. The 208. is pretty much useless except on trouble shooting problems as a voltage cheek. If I have 208V to ground on the power leg I know that both Tx's are hot to the high side.

Actually lots of stuff utilizes 208 single phase grounded or ungrounded. That we do not use 208 in a 240 center tapped delta is a NEC rule. But the equipment itself could care less if one side is grounded.

The 208. is pretty much useless except on trouble shooting problems as a voltage cheek. If I have 208V to ground on the power leg I know that both Tx's are hot to the high side. Note for this discussion I used two WYE / DELTA , additive polarity transformers. This is only one type of TX hook up there are many, wye /delta , open wye / delta , closed wye/ delta, closed delta/delta; and all are 120/240v or 240/480 as all delta secondary is. Grounded Wye 120/208v, 277/480v voltage is a hole other animal.

And here I have no clue what you are trying to say. Could you explain further.

 

[Avanti]

Yes I can just what is in need of clarification?

 

[kwired]

There are many types of delta transformer (TX) connections ether single phase or three phase. On a single phase transformer the most common type is the Wye high side and delta secondary side 120/240v the result. Three phase however is a different story, well we don't even need three high side (Primary or H1) phases. The open WYE/ DELTA can be used to make two 120v legs and light three phase secondary power from only two Primary phases and two Wye / Delta single phase TX's. This is a common connection for small apartment buildings for the there phase elevator load. This connection produces three phase secondary 240V power; using one TX for lighting load and the other for the power load. By tyeing the X1 of the power TX to the X3 of the lighting TX making three phases, by using a full coil on the power Tx and on half a coil on the lighting TX. The result is 120V on all the secondary legs and 240v phase to phase on all except the X3 of the power TX will be 208v to ground However; the same X3 leg phase to phase will yield 240v phase to phase. The 208V is measured phase to ground and this voltage is a result of the delta connection. I know of nothing that uses 208v volts to ground in this country or else were. The 208. is pretty much useless except on trouble shooting problems as a voltage cheek. If I have 208V to ground on the power leg I know that both Tx's are hot to the high side. Note for this discussion I used two WYE / DELTA , additive polarity transformers. This is only one type of TX hook up there are many, wye /delta , open wye / delta , closed wye/ delta, closed delta/delta; and all are 120/240v or 240/480 as all delta secondary is. Grounded Wye 120/208v, 277/480v voltage is a hole other animal.

Can you post a schematic of the "Wye-Delta" single phase transformer?

I have never seen a single phase transformer that was not a single winding high side and single winding low side, with possible taps for multiple voltages but essentially still one winding. They are supplied by conductors that are part of a three phase system at some point, unless you know of a power generation plant that only generates single phase power.

 

[Avanti]

I am new to on line posting and don't k now how to attach anything. Is there a guide somewhere so I can upload a image of a wye/delta.

 

[KenK]

I am an electronic technician by trade, not an electrician, but have been forced into performing electrician type work from time to time. I am always reluctant to more than the most basic work - I know the difference, and my limitations.

Anyway, 208V has always been a bit of a mystery to me, but your diagram using the triangle and pythagorean theory finally made it very clear to me.

My only question now, is why do we use 208V in the first place?

Thanks,

Goober Pat

Smaller conductors can be run, more efficient.

 

[CheapCharlie]

Over at Canadiana, they use 600Y/347v and put things together using square indented screws.

That made me laugh...good one. Robertson are the best screws around. Too bad US won't use anything invented in Canada. lol

 

[ilikepez]

I love Robertson screws. They also have an amazing story behind them.

 

[Electrician23]

The 208 V in the delta setup is just an artifact. We don't use it. In a three phase wye connected system where we want single phase 120 V, the phase to phase voltage turns out to be 208, and we use this just like we would 240 V in a single phase system, or all three phases for large loads.

Although 208 is not usually applied it is useful in some applications for example temporary lighting on most commercial or industrial job sites are 208 because you can almost double the amount of wattage as opposed to 120 allowing many more lights to be on a 20 amp circuit for example.

 

[Anthony young]

I have been doing Electrical for 15 years and I have never encountered the "High leg" configuration. So I understand that the high leg is always going to be the B phase and you should read 208v to ground. What is that leg used for? If I were going to wire a piece of equipment that was 3 phase, would I still connect it normally to a service with a high leg? For example: I had a 208v 3 phase airconditioner to be connected to a panelboard with a high leg. would I still connect it just the same on a 3 pole breaker or is there another way that its supposed to be connected? Also I'm wondering, if the B phase is 208v to ground in a panel board that is being used for lighting and recepacles then it sounds like I'm going to have to skip the B phase when connecting my 120v circuits or thats going to put 208v on my 120v lights or receptacles. Like I said, I have never encountered this type of service in my 15 years in the trade. I'm just trying to understand it.

 

[Anthony young]

In my experience a secondary of a single phase transformer is neither delta or wye.

What do you mean by TX?



The open delta transformers I have seen if the 120 VAC is derived on the secondary 3 phase was not available for motor loads? Can you post a link or diagram?

Are you referring to a center tapped winding for the 120 VAC?




Actually lots of stuff utilizes 208 single phase grounded or ungrounded. That we do not use 208 in a 240 center tapped delta is a NEC rule. But the equipment itself could care less if one side is grounded.



And here I have no clue what you are trying to say. Could you explain further.

Hey Brian, I'm new to this site and it looks like you are online. I just have a few questions about a service with a High Leg.
I have been doing Electrical for 15 years and I have never encountered the "High leg" configuration. So I understand that the high leg is always going to be the B phase and you should read 208v to ground. What is that leg used for? If I were going to wire a piece of equipment that was 3 phase, would I still connect it normally to a service with a high leg? For example: I had a 208v 3 phase airconditioner to be connected to a panelboard with a high leg. would I still connect it just the same on a 3 pole breaker or is there another way that its supposed to be connected? Also I'm wondering, if the B phase is 208v to ground in a panel board that is being used for lighting and recepacles then it sounds like I'm going to have to skip the B phase when connecting my 120v circuits or thats going to put 208v on my 120v lights or receptacles. Like I said, I have never encountered this type of service in my 15 years in the trade. I'm just trying to understand it.

 

[Roger]

I have been doing Electrical for 15 years and I have never encountered the "High leg" configuration. So I understand that the high leg is always going to be the B phase and you should read 208v to ground.

It's supposed to be but in real life there are always exceptions to a rule. You should always verify it with a meter.

What is that leg used for?

It doesn't have a real purpose, it's just a byproduct of the configuration.

If I were going to wire a piece of equipment that was 3 phase, would I still connect it normally to a service with a high leg?

If it were just straight 240 volt three phase yes, however if the equipment were 120/240 volt the high leg would have to be watched as to not connect it to controls or 120 volt circuits in the equipment.going to the the equipment

For example: I had a 208v 3 phase airconditioner to be connected to a panelboard with a high leg. would I still connect it just the same on a 3 pole breaker or is there another way that its supposed to be connected?

You would connect it like any other three phase connection.

Also I'm wondering, if the B phase is 208v to ground in a panel board that is being used for lighting and recepacles then it sounds like I'm going to have to skip the B phase when connecting my 120v circuits or thats going to put 208v on my 120v lights or receptacles.

And you are correct.

Like I said, I have never encountered this type of service in my 15 years in the trade. I'm just trying to understand it.

You have a pretty good grasp on it.

Roger

 

[wendon]

I have been doing Electrical for 15 years and I have never encountered the "High leg" configuration. So I understand that the high leg is always going to be the B phase and you should read 208v to ground. What is that leg used for? If I were going to wire a piece of equipment that was 3 phase, would I still connect it normally to a service with a high leg? For example: I had a 208v 3 phase airconditioner to be connected to a panelboard with a high leg. would I still connect it just the same on a 3 pole breaker or is there another way that its supposed to be connected? Also I'm wondering, if the B phase is 208v to ground in a panel board that is being used for lighting and recepacles then it sounds like I'm going to have to skip the B phase when connecting my 120v circuits or thats going to put 208v on my 120v lights or receptacles. Like I said, I have never encountered this type of service in my 15 years in the trade. I'm just trying to understand it.

Get out your Ugly's or look up transformer connection diagrams. It's not that difficult. Don't automatically assume that the high leg is on "B" phase. That's where it's supposed to be. In years gone by some of them were installed with the high leg on "C". The POCO won't necessarily install it on the "B" phase. If you connect 120 volt equipment to the high leg you will let out the magic smoke. Any 120/240 loads will need to be connected to "A" and "C". The easiest thing to do in my opinion is to install a separate single phase sub-panel for your 120/240 single phase loads. Don't assume that the high leg will be 208 to ground. Around here it's usually higher than that. I think the 240 volt Delta is better if you have a lot of motor loads but the high leg is a pain, especially for DIY's and hacks that learn the hard way!!

 

[Anthony young]

Thanks Wendon, Those were just examples. I have never worked on a system that is configured with a high leg and from what I have been reading, its not used that often so I may never even see one. I'm just trying to understand how that configuration works just in the event I ever do have to work on that configuration. If I did have to work on a system like that I would most definitely check for myself to determine which leg was the high one. My main curiosity was connecting 3 phase equipment to a panel that has a high leg. So your normal low voltage are black, red and blue. If I were going to connect some 3 phase equipment to a panel with a high leg, would I still connect it just the same on a 3 pole breaker? Or would that High Leg effect the equipment I was connecting? I'm new to this site, I just signed up this morning so I'm still figuring the site out. I got an email that you and also someone else replied to my question but I can't find the other reply. I'm going to have to check out the site more so I can get the hang of it. I really like it so far. Its a great way for us electricians to keep in contact with each other. I have a Journeyman license right now and I plan to take the master exam sometime this year so I think this site will help a lot while I'm preparing for the exam.