Turning 120v into 208v

[PeteEngel]

I agree. I had a long reply to the OP disappear on me and before I could get back a number of people have posted.

As a purely mental exercise it is interesting to consider. As practical exercise it is a HUGE waste of time.

Please, call ETC and ask if they consider their Sensor Rack as a power source for a makeshift 208v distro. Any number of projects have had people try and push the limits of whatever gear they have. Don't be a tragic statistic. My guess is that the UL rating of the Sensor rack will be void in this circumstance and any issues that arise will then be directly laid upon the facility and YOU (the OP).

The OP has already spent WAY TOO MUCH TIME on this dead end. But I do have an idea that would help. How about finding some Moving Lights that can operate on 110v power? If you have $100k to spend I'm sure they are out there.

Just Sayin'...

Jeez.

 

[lightguywcl]

I want to be perfectly clear so my TD understands this. I will not make a box that is "illegal" and "incorrect". He knows what my idea is and he knows I am in a discussion here to see if it is viable. When I came up with this idea I wanted to find out if it could work. So I thought this would be a good forum to ask this question. Where is the harm in doing this? I have not done anything other than explore the idea. With my knowledge I thought it could work so I asked this forum to people that have more knowledge than I. So as a result I have more knowledge than I did before. Even if it is a failed idea I still have learned something. I am sorry if I am frustrating some people I am just trying to understand better.

 

[lightguywcl]

The OP has already spent WAY TOO MUCH TIME on this dead end. But I do have an idea that would help. How about finding some Moving Lights that can operate on 110v power? If you have $100k to spend I'm sure they are out there.

I have already talked to my TD today and told him that it is better to go with 8 martin vipers and 8 auras along with a grand ma 2 lite. We will see how close we are to get to that $150,000.00 and then see what else we can add to it. I would like to thank everybody's comments it has helped me to decide what to do. So yes it is purely a mental exercise at this point but I would still like to know more about why it won't work for my own information. Again thank you.

 

[RonHebbard]

I agree that is the biggest problem. The head of maintenance at my theater worked at UL for a period of time and he has some interesting stories. If it is in fact illegal to have 2 single pole breakers feed a double pole breaker even though it is less amperage. Then I will no longer argue this point. So if it is illegal then it probably has been tested. I am curious on what fails. The Sensor rack is the circuit cannot be de-energized by a common breaker. I am trying not to be dumb but why is that a problem?

Hello!

I'm flogging the horse here but please permit me to elaborate on a couple of things Steve Terry told you.
ETC uses magnetic trip breakers, as they should / must.
A 20 amp magnetic trip breaker could easily trip before a thermal trip 15 amp breaker.
No one would be surprised and no laws of physics would be broken.

If you use a pair of single pole breakers to feed your downstream common trip pair of breakers, when one of the source breakers trips, power from the second source breaker will pass through one pole of your common trip breaker, continue through your load, return, backwards as it were, through your other common trip breaker and end up on the load terminal of the source breaker that tripped. This can really catch folks off guard when they meter before and after a tripped breaker and find voltage on both sides. They can also be easily caught off guard, and/or killed, when a load device ceases to function yet is still sitting there with 120 volts just waiting for an unsuspecting grounded human being to innocently dig into it.

I'm sorry if we're not getting through to you and I don't want you to feel that a bunch of jerks on the internet are ganging up on you for fun and amusement. I just wish I could find the words to convince you that you've received a lot of great advice from a lot of very experienced people who're giving of their time for free all in an effort to help and educate you.

EDIT: I too began writing this post a while ago and note several posts have added to this thread whilst I was typing away.

I'll quit flogging and go away now.

Steve? We met for two days in a boardroom in your then new New Jersey shop back in 1995 when about a dozen of us were gathered to plan taking 'Tommy' to Frankfurt dancing to the rules of TUV. I ended up spending six weeks in a really nice Frankfurt hotel and returned home to Canada with too, too many really silly stories, mostly involving German rental shops and too long to get into here.
Are you still in touch with Dave Grill?
Ask Dave about him and the VL programmer, drunk as skunks, standing amidst the pitchers on a large circular table belting out 'God Bless America' in a room of 1,000 elegantly dressed German folks singing their national anthem at the Tommy opening night party while Gene O'D and Linda Batwin were trying to slide out of sight under the table in embarrasment.

Dealing with TUV actually worked out well in the end, smuggling six bottles of A1 steak sauce into Germany had a lot to do with it.

Toodleoo!
Ron Hebbard

 

[lightguywcl]

If you use a pair of single pole breakers to feed your downstream common trip pair of breakers, when one of the source breakers trips, power from the second source breaker will pass through one pole of your common trip breaker, continue through your load, return, backwards as it were, through your other common trip breaker and end up on the load terminal of the source breaker that tripped. This can really catch folks off guard when they meter before and after a tripped breaker and find voltage on both sides. They can also be easily caught off guard, and/or killed, when a load device ceases to function yet is still sitting there with 120 volts just waiting for an unsuspecting grounded human being to innocently dig into it.

Wow I had no idea that that would happen. So what that would mean then if I understand what you are saying that if one leg trips then the tripped side becomes the neutral of the other hot leg? Is that correct? When I talked to the tech at vari-lite he said that if you lost one leg it would still work on 120v just not as bright. In this instance it would be really difficult to meter both sides of the tripped breaker since it would be a etc dimmer module. I can't think of how I could meter it even if I wanted to since it is hard wired back to the dimmer rack. I maybe able to open a junction box but why would I want to. The most likely cause of the tripped breaker is the vl3000 which would have to cause such an action that would not blow the internal fuses and get past the double pole breaker and finally trip the 20 amp single pole breaker. I don't even know if that is possible at the most it is unlikely. The only other way it could trip would be a short circuit in the wiring which would also be unlikely but possible.

I'm sorry if we're not getting through to you and I don't want you to feel that a bunch of jerks on the internet are ganging up on you for fun and amusement. I just wish I could find the words to convince you that you've received a lot of great advice from a lot of very experienced people who're giving of their time for free all in an effort to help and educate you.

I have been in other forums and there have been times where people posting threads are not sure how they are coming across. I have said this before and I will say it again I really do appreciate the information I am getting from everybody. I have not felt for a moment that you are a bunch of jerks.

 

[sk8rsdad]

the tripped side becomes the neutral of the other hot leg? Is that correct?.

Sorry if this seems a bit like Electricity 101, especially to somebody with 20 years experience but...

An electrical circuit needs a closed path from source to load and back again. We use the terms hot and return to describe the two connections between source and load.

Don't confuse the term return with the term neutral. In a single-phase circuit, both the hot and neutral are power carrying conductors and the only distinction is that the neutral is bonded to ground at some point. The electrons that change direction 60 times a second in North America don't care which connection is which. They are happily flowing around a closed circuit.

In a 208V circuit provided by a 3-phase Wye (Y) system, there is no neutral. The return is another hot leg, phase-shifted by 120 degrees. If the voltage on either leg is measured relative to ground, both will read 120V. Neither leg is bonded to ground.

Since neither leg in a 208V circuit is bonded to ground, a common double-pole circuit breaker is required to de-energize both legs simultaneously. Failing to de-energize both legs at the source means there is 120V difference between one of the wires in the load and ground. Touching that live wire is hazardous to your health.

 

[RonHebbard]

In a 208V circuit provided by a 3-phase Wye (Y) system, there is no neutral. The return is another hot leg, phase-shifted by 120 degrees. If the voltage on either leg is measured relative to ground, both will read 120V. Neither leg is bonded to ground.

Since neither leg in a 208V circuit is bonded to ground, a common double-pole circuit breaker is required to de-energize both legs simultaneously. Failing to de-energize both legs at the source means there is 120V difference between one of the wires in the load and ground. Touching that live wire is hazardous to your health.

Hello "dad"!
(I far prefer forums where folks use their real names like Steve Terry.)

First of all, thank you for picking up the torch, the OP means well, and I appreciate his desire for education but as with a few other posters he's wearing me down.
I believe I've caught you in a minor typo that ought to be made crystal clear to the OP.
"In a 208V circuit provided by a 3-phase Wye (Y) system, there is no neutral."
A delta sourced system would have no neutral.
A Wye sourced system has a neutral, and by most codes it would be bonded to ground at source, but you may choose not to use the neutral or bring it out from the transformer.

Another possible misunderstanding for the OP.
"Since neither leg in a 208V circuit is bonded to ground, a common double-pole circuit breaker"
I suspect you meant to type 'a double-pole common trip circuit breaker', the trip being common rather than the breaker.

Somewhere far back in this thread, I recall someone alluding to the VL's possibly developing 120 VAC internally by taking a reference from ground as they're not bringing a neutral into the unit. If this is true, I suppose I can understand some of what the OP is attributing to his VL tech.

Thanks again "dad" for continuing the good fight against well intentioned assumptions and dangerous electrical practices.

Oh! In my part of Canada, the electrons change direction 120 times per second completing each full cycle 60 times per second at a good time on a good day when the load's not too heavy and the water's running over the falls real good!

Toodleoo!
Ron Hebbard

 

[lightguywcl]

So my error was saying that it becomes a neutral. I should have said acts like a neutral or used the term return that would describe that the tripped leg would have voltage on it. Now that I think about it "saying acts like a neutral may not be much better" Now that I read it again it does seem silly that I used the term "becomes" like it happened magically. Sorry, poor choice of words. I don't know if there would be voltage on the tripped side. I would think it would depend on what made the breaker trip in the first place. I did know the difference but thanks for the refresher course. I do not think of electricity that much anymore so it is good to remember it again. Everybody keeps on talking about that hot wire. All I can say is it would be really difficult to touch. You would have to get into the back of the rack or take the connector off. Now who would really take a connector off without shutting all of the breakers off anyway.

 

[JD]

The "tripped leg" would still have full line voltage on it. The "load" simply allows the voltage on the opposing hot to flow through it. Since the circuit is now open, no work is being done, but it you were to meter the open leg (assuming 208/120), you would find it 120 volts above ground, but with 0 volts across the load. Because of this, the conductor that is thought to be dead presents a shock hazard. The only exception to this case would be if the tripped line was shorted to ground. At that point, the load would have 120 volts across it instead of 208. More important, when the source of the short was found and corrected, the conductor would jump up to 120 volts and again become a shock hazard. This is why the "break" must be made by a double pole breaker, so that no voltage and shock hazard are present in the shut-down circuit (past the breaker itself.)

 

[lightguywcl]

The "tripped leg" would still have full line voltage on it. The "load" simply allows the voltage on the opposing hot to flow through it. Since the circuit is now open, no work is being done, but it you were to meter the open leg (assuming 208/120), you would find it 120 volts above ground, but with 0 volts across the load. Because of this, the conductor that is thought to be dead presents a shock hazard. The only exception to this case would be if the tripped line was shorted to ground. At that point, the load would have 120 volts across it instead of 208. More important, when the source of the short was found and corrected, the conductor would jump up to 120 volts and again become a shock hazard. This is why the "break" must be made by a double pole breaker, so that no voltage and shock hazard are present in the shut-down circuit (past the breaker itself.)

I don't think it can be explained better than that. I would again like to thank everybody's time and input. I am now going to enjoy finding gear to spend with my $150,000.00 lighting budget. I would welcome any input anybody has on that subject although I may have to start a new thread. Again thanks.

 

[RonHebbard]

Hello again and again "lightguy..."

Two quick points and I'll go away again.

Back to the scenario where one of your two source breakers trips.
Unless the related load wiring has gone solidly to ground or burned its self open somewhere along the way, all of the load wiring will still have 120 VAC on it with respect to ground, all of it!
You wouldn't need to get into your dimmer rack to get a shock.
If one of your two source breakers tripped, and if your load wiring has not gone solidly to ground or burned its self clear, there would be volage present on the load side of your tripped breaker, no buts or maybes about it.

I guess one of the several dangers here is many of us think we've already explained things but, unless you write back, we've no real way of knowing what you understood from our efforts.
I keep feeling we're not getting through to you and I apologize for my inability to adequately express myself with greater clarity.
Keep coming back and I'll try not to give up on you.

Toodleoo!
Ron Hebbard

 

[lightguywcl]

If one of your two source breakers tripped, and if your load wiring has not gone solidly to ground or burned its self clear, there would be volage present on the load side of your tripped breaker, no buts or maybes about it.

I appreciate you hanging in there with me so I will stay in it until I completely understand. I know that the power from the untripped leg is being powered by the tripped leg. Since this is an unconventional set up a person not knowing that could shock himself. The connection would be inside the vl 3000 somewhere. I would think then if anybody unplugged any of the possible connections along the way or shut off the double breaker there would be no voltage on the tripped leg. Is that correct? I think everybody knows the setup by now. I know why the electricity is running the way it is. I still don't see how anybody can get shocked even if they don't know the tripped leg is not safe. I honestly can't come up with a scenario. So you offered to help me Ron. Assuming everything else I said was correct it would be a big help if you can come up with a scenario were I can't.

 

[len]

Other options:

Buy a combo distro and dimmer rack (Applied makes them to order, among others) and sell a dimmer rack or two.

Rent a distro as needed

 

[lightguywcl]

Other options:

Buy a combo distro and dimmer rack (Applied makes them to order, among others) and sell a dimmer rack or two.

Rent a distro as needed

Interesting idea I will talk to the people that will be upgrading the dimmer racks to see how much it would be. Now that I will be going the 110v option I will be buying R20 etc modules. I was surprised that they were $450.00 a piece and since they are doubles circuiting them will be problematic. I wish they made just one side a relay. I made several relay dimmers for a nearby theater in a cd80 rack. Those are easy to work on. In this age of moving lights. The future theater may have more straight AC power.

 

[RonHebbard]

I appreciate you hanging in there with me so I will stay in it until I completely understand. I know that the power from the untripped leg is being powered by the tripped leg. Since this is an unconventional set up a person not knowing that could shock himself. The connection would be inside the vl 3000 somewhere. I would think then if anybody unplugged any of the possible connections along the way or shut off the double breaker there would be no voltage on the tripped leg. Is that correct? I think everybody knows the setup by now. I know why the electricity is running the way it is. I still don't see how anybody can get shocked even if they don't know the tripped leg is not safe. I honestly can't come up with a scenario. So you offered to help me Ron. Assuming everything else I said was correct it would be a big help if you can come up with a scenario were I can't.

Hello!

If you trip, or turn off, your common trip breaker, or unplug any extension cable connectors downstream of it, then everything downstream of wherever you broke all of your conductors will be de-energized / safe.
An example of a hazardous scenario would be one of your two source breakers tripping, or being inadvertantly switched off, the VL appearing to be without power and someone innocently opting to service the VL not realizing it was still partially powered.

All the best.

Toodleoo!
Ron Hebbard

 

[derekleffew]

... and since they are doubles circuiting them will be problematic. ...

Under your previous scheme, you were willing to sacrifice 24 channels of dimming to gain 12x L6-20 outlets. Now you're concerned about having to swap modules in multiples of two?

... Now that I will be going the 110v option I will be buying R20 etc modules. I was surprised that they were $450.00 a piece and since they are doubles circuiting them will be problematic. I wish they made just one side a relay. ... The future theater may have more straight AC power.

It sounds like plans are in the works to upgrade your Sensor Classic or Sensor+ dimmer rack (s) to Sensor3 (and I would question whether the expense of this upgrade can be justified), in which case some ThruPower modules would provide the flexibility you seek.

Other options:
Buy a combo distro and dimmer rack (Applied makes them to order, among others) and sell a dimmer rack or two.

Replacing ETC Sensor dimmers with those from Applied Electronics? Not sure I see the wisdom in that scenario.

... I made several relay dimmers for a nearby theater in a cd80 rack. Those are easy to work on. In this age of moving lights. The future theater may have more straight AC power.

Let's not talk about modifying the dimmers in a CD80 rack, okay?

 

[RonHebbard]

In this age of moving lights. The future theater may have more straight AC power.

The newly built venues I've worked on most recently used the same theatrical lighting and rigging consultants out of NYC, NY.
DMX controlled relays powered receptacles throughout the venues for their 'wiggle light' power; 48 - 20 amp single pole breakers and relays for 120 VAC receptacles plus 48 - 20 amp double pole common trip breakers and double pole relays for 208 volt receptacles. In my area of Canada this appears to be where things are currently, pardon the accidental pun, at.
As you wrote, more and more straight, non-dimmed, DMX controllably switched power.

Toodleoo!
Ron Hebbard

 

[lightguywcl]

Thank you for the info I will talk to the rep to see what they can do for me for ML power. I am sure this is starting to be a common question.

 

[sk8rsdad]

Hello "dad"!
(I far prefer forums where folks use their real names like Steve Terry.)

I prefer otherwise. I don't work in entertainment and would prefer to make it just a tiny bit harder for others to stitch my life story together from things I have published on the internet. Now where did I leave my tinfoil hat?

FWIW, there's no way to confirm that Steve Terry really IS Steve Terry. It could be a Nigerian prince posting via a proxy server in Middleton. t doesn't matter though because whoever is posting as Steve Terry is providing really good advice.

I believe I've caught you in a minor typo that ought to be made crystal clear to the OP.
"In a 208V circuit provided by a 3-phase Wye (Y) system, there is no neutral."

I think your correction may have contributed more confusion than clarification. It certainly clouds the intent behind my post.

Perhaps I should have phrased it as "in a 208V circuit in a Y system, the neutral does not participate." But then I would have had to say something about how none of the legs were bonded to ground because that bonding happens elsewhere. And then I would have had to talk about Tesla, Westinghouse, and Edison and all those other things that really only he understood about polyphase power and most of the rest of us muddle through in order to pass an electrical engineering exam.

A delta sourced system would have no neutral.

In a Delta system, one of the legs might be bonded to ground and hence be considered a neutral. Assuming such a bond exists there's a chance a single-pole circuit breaker would actually de-energize the circuit. It would still be silly to use multiple single-phase breakers to de-energize it.

Another possible misunderstanding for the OP.
"Since neither leg in a 208V circuit is bonded to ground, a common double-pole circuit breaker"

I suspect you meant to type 'a double-pole common trip circuit breaker', the trip being common rather than the breaker.

I yield to your pedantry. You are, of course, correct. The breakers are quite common though. I can lay my hands on one with very little effort.

 

[lightguywcl]

Under your previous scheme, you were willing to sacrifice 24 channels of dimming to gain 12x L6-20 outlets. Now you're concerned about having to swap modules in multiples of two?

Not sure yet I will let you know when I get back to the theater. I just know that when I stick a R20 module in the numbers may not be next to each other. It is a concern until I figure it out.

It sounds like plans are in the works to upgrade your Sensor Classic or Sensor+ dimmer rack (s) to Sensor3 (and I wold question whether the expense of this upgrade can be justified), in which case some ThruPower modules would provide the flexibility you seek.

I know for a fact that we are switching out our unison system to a new paradigm system. At the time he inspected the unison system he looked at our dimmers. He said that the ECM modules were being phased out and that it would be difficult to get them repaired in the future. I know that was not a pressing need. Because of how our budget was my TD thought it might be better to do it now since we were going to have to do it eventually. I will ask tomorrow if we are going to do it. Why don't you think the upgrade can be justified?