Voltage

[mstrlucky74]

Why are panels listed as 120/208v when the line to line voltage is actually 240V? I hear 208,220 and 240v used interchangeably when referring to the same thing. Thanks.

 

[LarryFine]

Why are panels listed as 120/208v when the line to line voltage is actually 240V? I hear 208,220 and 240v used interchangeably when referring to the same thing. Thanks.

Panels are rated for a maximum voltage, but may be labeled for an existing supply.

And, 120/208v (properly 208Y/120) is not 240v. On 120v L-N 1ph or 3ph D, L-L is 240v; on 120v L-N 3ph Y, L-L is 208v.

220v and 240v are used interchangeably, but the former is now a utilization equipment rating, and the latter a supply rating.

 

[ptonsparky]

Why are panels listed as 120/208v when the line to line voltage is actually 240V? I hear 208,220 and 240v used interchangeably when referring to the same thing. Thanks.

Typically the 120/208 would be reference a three phase Wye system although only two hots and a neutral could be used and often are in apartment buildings, etc. For those that know, the order of those numbers are important. IDR.

IDR who had a post on the history of all the different voltage levels that actually reference the same single phase 120/240 that we use in most residential settings. IIRC it was because the voltages were lower. 110/220, 115/230, 120/240.

 

[ggunn]

Panels are rated for a maximum voltage, but may be labeled for an existing supply.

And, 120/208v (properly 208Y/120) is not 240v. On 120v L-N 1ph or 3ph D, L-L is 240v; on 120v L-N 3ph Y, L-L is 208v.

220v and 240v are used interchangeably, but the former is now a utilization equipment rating, and the latter a supply rating.

Back when I was just getting started in power (I was in semiconductors for many years before that) I got burned by something like this. I was designing 11 PV systems for a school district and all the building MDPs were 480V rated and labeled as such. One of them, however, was only utilized at 208V, and we (I) didn't catch it until the installation was underway. It was an expensive and embarrassing error.

 

[infinity]

Why are panels listed as 120/208v when the line to line voltage is actually 240V? I hear 208,220 and 240v used interchangeably when referring to the same thing. Thanks.

Where are you working that has 240 volts? The correct nomenclature for 3Ø is 208Y/120. For the record 208 and 240 are not the same thing, they're from completely different systems.

 

[paulengr]

Where are you working that has 240 volts? The correct nomenclature for 3Ø is 208Y/120. For the record 208 and 240 are not the same thing, they're from completely different systems.

Ever heard of high leg delta? It is very common. It is almost always 120/240. The three phases are 240 V at the transformer with a 230 V utilization voltage. But the neutral is at the midpoint between the two non-high legs so they can be used as 240/120 single phase. The high leg can be used as 208 V single phase but almost never is.

The way this is achieved most commonly is by using a second 240/120 transformer connected between the third previously unused phase and either of the two existing phases. A third transformer is not strictly necessary since it is simply a broken delta although it is less efficient than a true three phase 3 coil transformer.


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[infinity]

Ever heard of high leg delta? It is very common. It is almost always 120/240. The three phases are 240 V at the transformer with a 230 V utilization voltage. But the neutral is at the midpoint between the two non-high legs so they can be used as 240/120 single phase. The high leg can be used as 208 V single phase but almost never is.

The way this is achieved most commonly is by using a second 240/120 transformer connected between the third previously unused phase and either of the two existing phases. A third transformer is not strictly necessary since it is simply a broken delta although it is less efficient than a true three phase 3 coil transformer.


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I'm very familiar with high leg Delta but the OP stated that the panels are listed as 208/120 which has little to do with a Delta system.

 

[Besoeker3]

I think I'll stick with our simple 400/230 system............

 

[MAC702]

I think I'll stick with our simple 400/230 system............

Have you settled on which color to use as the neutral yet?

 

[Besoeker3]

Have you settled on which color to use as the neutral yet?

Blue. But I don't think we settled on it. I think it was imposed on us as part of the European "harmonisation" process.
Blue was one of the three phase line colours. Now black, which was neutral, is now one of the line colours. Imagine installing new wiring and having to interface with an existing old system. Madness.

 

[augie47]

Blue. But I don't think we settled on it. I think it was imposed on us as part of the European "harmonisation" process.
Blue was one of the three phase line colours. Now black, which was neutral, is now one of the line colours. Imagine installing new wiring and having to interface with an existing old system. Madness.

Borris is going to fix that !

 

[Besoeker3]

Borris is going to fix that !

A little tale.
An acquaintance of mine was building a house in France. He posted some pictures during the process. The supply was three-phase. His conductor colours were red, yellow, and blue for the phases and black for the neutral. The very colours that had become illegal in UK.

Call me a cynic but what I think happened is the cables that were in stock in UK with the old colours had to be ditched and other countries "acquired" them dirt cheap.

 

[LarryFine]

When I discovered UK colors, I thought it would have made more sense for blue (color of sky) to be hot and brown (color of earth) to be grounded.

 

[Besoeker3]

When I discovered UK colors, I thought it would have made more sense for blue (color of sky) to be hot and brown (color of earth) to be grounded.

You have a point.
What really irks me, and many others, is that we went from the three distinctive primary colours, red, yellow, and blue to insipid brown, black, and grey. Who does that help?

Sorry mods - off topic I know.