Turning 120v into 208v

If you use those cables say for a practical and wire up a medium screw base lamp socket and your hot/neutral is reversed, the button contact is now neutral and the screw contact is hot. Potentially a dangerous scenario and not at all an expected wiring configuration.

Now remember I don't play with these plugs in actuality, just in theory.
But this comment perplexes me...
As I understand it, X and Y are 2 actives, so neither of them is at neutral potential and it seems unlikely that anyone would ever be using a 208 / 240 lamp in a practical, everything I've come to understand about your slightly eccentirc electrical system suggests that would be done down at 120...
 
Now remember I don't play with these plugs in actuality, just in theory.
But this comment perplexes me...
As I understand it, X and Y are 2 actives, so neither of them is at neutral potential and it seems unlikely that anyone would ever be using a 208 / 240 lamp in a practical, everything I've come to understand about your slightly eccentirc electrical system suggests that would be done down at 120...

The older style twist lock connectors (known as tit out) used for 120v distribution, I think they are L7-20's (can't remember) was once a Brass (Hot), Copper (Neutral) plus ground configuration. The male was not a "dead front" connector, instead had a fibre plate covering the screw terminals and neither the male nor the female had any X,Y,Z indications. Then the connector got changed to a 2 hot with ground configuration, became the modern dead front design and got indicators for X and Y, but stayed "tit-out". This is still the only twist locking style connector that interfaces with the the original design (in old spaces) and is what's used.

For assorted reasons, our space using twist, which was supposed to convert to 2P&G 2 years ago, has not, thus we continue to use twist. Hate them.
 
SteveB, Chris15, (et al), see the wiki entry TLGO (and TLGI) (and the thread http://www.controlbooth.com/forums/...38-old-non-nema-pin-out-style-twistlocks.html ). When wiring this connector for 250V (H,H,G) it doesn't matter which hot XY goes to brass or copper colored terminals. When wiring for 120V (H,N,G) black H should go to brass, and white N should go to copper (I think, see below), but it's understandable how this could get confused.

At least it's not the connector discussed here, which is neither ground-out nor ground-in:
... as for wiring, yes, the biggest blade is ground, and the blade at the 4 to 5 o'clock position "should" be the Neutral, but that should be indicated inside the connector. ...
So with the largest (ground) blade at 12, the non-copper blade at 4-5 is the "neutral," and the copper blade is "hot"?
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...

The above makes me grateful for how far we've come thanks to NEC, UL, NEMA. It's nice being reasonably certain of voltage and polarity when encountering any connector. Sadly, we can never be 100% without testing due to scofflaws and ignoramuses.
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The older style twist lock connectors (known as tit out) used for 120v distribution, I think they are L7-20's (can't remember) was once a Brass (Hot), Copper (Neutral) plus ground configuration. The male was not a "dead front" connector, instead had a fibre plate covering the screw terminals and neither the male nor the female had any X,Y,Z indications. Then the connector got changed to a 2 hot with ground configuration, became the modern dead front design and got indicators for X and Y, but stayed "tit-out". This is still the only twist locking style connector that interfaces with the the original design (in old spaces) and is what's used.

For assorted reasons, our space using twist, which was supposed to convert to 2P&G 2 years ago, has not, thus we continue to use twist. Hate them.

Tit-out twist-loks are non NEMA rated. They have a dual 125/250V rating--which is precisely why they are non-NEMA. Unlike the 2P&G pin plug dual voltage rating, which requires one conductor to be a grounded neutral--the tit-out rating is hot-neutral at 125V and hot-hot at 250V. That's why they disappeared over the last 20 years.

ST
 
I appreciate all the comments I have got so far and I have tried to come up with a plan that most people would agree with. I went into work today and tested my socoapex breakouts. Circuit 1-x, 2-y, 3-y, 4-z, 5-z, 6-x. So I do get 2 of each leg in all of my breakouts. So my plan is to get 24 cc modules and build two circuit breaker boxes with two male socoapex connectors going in and one female going out. With 6 15 amp double pole breakers in the middle. I plan on hanging it right on the pipe that the movers are on. This is the cheapest and code friendly idea I have come up with so far to get 208v. I am interested in what everybody thinks. Thank you.
 
I appreciate all the comments I have got so far and I have tried to come up with a plan that most people would agree with. I went into work today and tested my socoapex breakouts. Circuit 1-x, 2-y, 3-y, 4-z, 5-z, 6-x. So I do get 2 of each leg in all of my breakouts. So my plan is to get 24 cc modules and build two circuit breaker boxes with two male socoapex connectors going in and one female going out. With 6 15 amp double pole breakers in the middle. I plan on hanging it right on the pipe that the movers are on. This is the cheapest and code friendly idea I have come up with so far to get 208v. I am interested in what everybody thinks. Thank you.

There is no way that every single breakout has that exact configuration in how the phases line up. Though I can not site the exact code, I can't imagine a situation where a common throw breaker is allowed downstream of two non common throw breakers is allowed. If you have an issue on the line, you run the risk of the breaker on the dimmer rack blowing instead of the breaker on the load side, especially when both breakers are rated the same. It is pretty much a crap shoot as to which one will blow first.

I don't think we can say this enough here... there is NO LEGAL OR SAFE WAY in which you will be able to get 208v service out of your currently installed sensor rack and distribution. If you can't afford to do it right, you should not be doing it. If your looking at buying a 100k in fixtures, I have no clue what your problem is with purchasing a proper distro. Why would you jump through all of these hoops to save a few grand?

Here is one for 2k:LEX 200 Amp 3 Phase Moving Light Box | Power Distribution Boxes for Stage, Theatre and Live Performance | PNTA
Two 100' socapex cables for a grand: https://www.gearsource.com/catalog/listing/40175
Two nice L6-20 Breakouts for 300 bucks: https://www.gearsource.com/catalog/listing/49971
and some oversized feeder for a grand: 50' Feeder Cable

So, $4,500 and you have 12-20amp circuits of 208v power that is safe. So, what is the deal? Why are you jumping through these hoops? 5k is nothing crap compared to what 10 top level movers cost. You will spend 5k a year alone in lamps and maintenance on 10 units.
 
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I appreciate all the comments I have got so far and I have tried to come up with a plan that most people would agree with. I went into work today and tested my socoapex breakouts. Circuit 1-x, 2-y, 3-y, 4-z, 5-z, 6-x. So I do get 2 of each leg in all of my breakouts. So my plan is to get 24 cc modules and build two circuit breaker boxes with two male socoapex connectors going in and one female going out. With 6 15 amp double pole breakers in the middle. I plan on hanging it right on the pipe that the movers are on. This is the cheapest and code friendly idea I have come up with so far to get 208v. I am interested in what everybody thinks. Thank you.

There is no way that every single breakout has that exact configuration in how the phases line up. Though I can not site the exact code, I can't imagine a situation where a common throw breaker is allowed downstream of two non common throw breakers is allowed. If you have an issue on the line, you run the risk of the breaker on the dimmer rack blowing instead of the breaker on the load side, especially when both breakers are rated the same. It is pretty much a crap shoot as to which one will blow first.

I don't think we can say this enough here... there is NO LEGAL OR SAFE WAY in which you will be able to get 208v service out of your currently installed sensor rack and distribution. If you can't afford to do it right, you should not be doing it. If your looking at buying a 100k in fixtures, I have no clue what your problem is with purchasing a proper distro. Why would you jump through all of these hoops to save a few grand?

Here is one for 2k:LEX 200 Amp 3 Phase Moving Light Box | Power Distribution Boxes for Stage, Theatre and Live Performance | PNTA
Two 100' socapex cables for a grand: https://www.gearsource.com/catalog/listing/40175
Two nice L6-20 Breakouts for 300 bucks: https://www.gearsource.com/catalog/listing/49971
and some oversized feeder for a grand: 50' Feeder Cable

So, $4,500 and you have 12-20amp circuits of 208v power that is safe. So, what is the deal? Why are you jumping through these hoops? 5k is pigeon crap compared to what 10 top level movers cost. You will spend 5k a year alone in lamps and maintenance on 10 units.

Based on footers links your not saving any money at all by doing it the wrong way. I still don't understand why your so driven to use the dimmer rack for power after we've all told you it can't work.

24 cc modules will run you about $3230 plus shipping at production advantage, so yeah maybe you could find them a little bit cheaper.
$500 for breakers boxes and breakers (ballpark guess)
$500 in Soca connectors for the breakers boxes
$300 L6-20 breakouts
$600 stage pin break in's

That's already got the total up to $5130, not including all of the labor to build those illegal breaker boxes which won't be cheap. And you've also lost 24 channels of dimming that may need to be replaced $$$.

And then there are the really big costs to think about. The first one is your show getting shutdown by the fire marshal or another inspector, when they see breaker boxes in the air you won't have time to think up a reason before they shut you down. What happens when something fails does serious damage to your dimmer rack? And then there is the big fat lawsuits that will come raining down on you and the venue when someone gets hurt from this.

Please do us all a big favor and save a few dollars by doing it the right way.


$
 
... I went into work today and tested my socoapex breakouts. Circuit 1-x, 2-y, 3-y, 4-z, 5-z, 6-x. So I do get 2 of each leg in all of my breakouts. ...
There is no way that every single breakout has that exact configuration in how the phases line up. ...
One would hope all the breakouts are wired according to industry standard: http://www.tmb.com/images/stories/6-circuitpinout-ltr.pdf .
Now IF (big if) the female socapex outlets (dimmer outputs) are wired starting as mult circuit#1 is dimmer#2 [or 8, or 14, or 2+(x*6)], then phasing would indeed be "1-x, 2-y, 3-y, 4-z, 5-z, 6-x."
But it's more likely each soca outlet begins with: 1, 7, 13, 19 ... 1+(x*6), in which case the phasing would be 123456=XXYYZZ.

Which brings up a, very real, potential issue with the proposed scheme: if the outlets are not all wired the same, or start with the same phase dimmers, or a multi-cable has crossed wires, or a break-out has a hot-neutral reverse; any of seemingly minor errors will cause the system to be: inoperable at best, unsafe at worst.

... and build two circuit breaker boxes with two male socoapex connectors going in and one female going out. With 6 15 amp double pole breakers in the middle. I plan on hanging it right on the pipe that the movers are on. This is the cheapest and code friendly idea I have come up with so far to get 208v.
Will this "box" be designed, assembled, and tested by a UL Listed 1640 assembler? How does the theatre's insurance carrier feel about the use of a "homemade" piece of electrical distribution equipment?

... This is the cheapest and code friendly idea I have come up with so far to get 208v. I am interested in what everybody thinks. Thank you.
Cheapest = no.
Code friendly = no.

If you insist in not using a dedicated ML PD (the consensus here), consider this listed, by NRTL device: Quick 220 Systems: Model A220-20L <br />20 Amp Power Supply <br />Twist Locking Outlet as discussed in here: http://www.controlbooth.com/forums/lighting-electrics/19720-115-volt-ac-220-volt-ac.html#post179043 . The specs don't mention it working with 120/208V bi-phase, so I would inquire before purchase. I don't see why it wouldn't. I also don't see why anyone would want to introduce such a point of potential failure into his system, but there you go.
EDIT: Response from the manufacturer:
Thank you for asking about Quick 220 systems. In answer to your question, the Quick 220 can be used on the two 120V circuits of a 3 phase Wye system. As you indicated, the output voltage is then 208 volts, nominal. Although we don't emphasize 3 phase power as a source, it is covered on the specification section of the product page: http://www.quick220.com/-A220-20L.html . Although the output with 3 phase is 208 volts, nominal, we give the range of "187 to 216 Volts AC (1.732 times input voltage)” which reflects the output if the input varies from 120 volts.
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... and some oversized feeder for a grand: 50' Feeder Cable
From the listing:
50' Feeder Cable with Cam-Locks. Red Blue & Black are 4/0 cable. White and Green are 2/0 cable.
1. Don't buy from a vendor who can't spell cam-lok.
2. We've discussed previously code compliability of using a smaller ground, but I don't think we've ever discussed an under-sized neutral.
3. For this particular application (feeding a 200A distro), a 2/0 neutral is acceptable. Even more so when one considers that the neutral isn't even connected to the outputs (except for the "(1) NEMA 5-20, 20 Amp, 2 Pole, 3 Wire, 120 VAC, duplex receptacle" convenience outlet on the LEX pagoda box). But this assembly wouldn't be permitted to supply a dimmer rack.
4. We've also discussed previously the derating required when 4/0 feeder is bundled.

.
 
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O
1. Don't buy from a vendor who can't spell cam-lok.
2. We've discussed previously code compliability of using a smaller ground, but I don't think we've ever discussed an under-sized neutral.
3. For this particular application (feeding a 200A distro), a 2/0 neutral is acceptable. Even more so when one considers that the neutral isn't even connected to the outputs (except for the "(1) NEMA 5-20, 20 Amp, 2 Pole, 3 Wire, 120 VAC, duplex receptacle" convenience outlet on the LEX pagoda box). But this assembly wouldn't be permitted to supply a dimmer rack.
4. We've also discussed previously the derating required when 4/0 feeder is bundled.

.

One would also hope that you would not buy an entire rig off of gearsource... there are much better prices out there if you just pick up the phone!

The point of the post was not to spec gear for his exact rig but instead to show that you can buy what you need for pennies compared to the cost of the fixtures themselves. Personally though if I had a 400 amp company switch I would probably buy 4/0 feeder anyway. It is not that much more after you figure in the connectors and shipping. Down the line your not purchasing new cable if you want use the full capacity of the switch. Now, if I had to move it every day I would be singing a different tune... and rather loudly.
 
The original point of this post was to find out if my idea was legal and cost effective. My TD will not allow me to do it if it isn't. I have been a Head Electrician for 20 years and I will not build something if I feel that it is in anyway unsafe.

My thought was to first figure out if it was safe. If it was not then I did not need to find out if it was cost effective.

There is no way that every single breakout has that exact configuration in how the phases line up

Which brings up a, very real, potential issue with the proposed scheme: if the outlets are not all wired the same, or start with the same phase dimmers, or a multi-cable has crossed wires, or a break-out has a hot-neutral reverse; any of seemingly minor errors will cause the system to be: inoperable at best, unsafe at worst.

It is true I have not tested every breakout but I have tested every breakout I plan on using and they are the same. I have been using the term breakout but that is for testing purposes only. I am using one breakout and moving it to the places I want to test. So there is no problem with a hot-neutral reverse. I can only say that it has been the same so far and I will test more of them if I plan on going ahead with this.

If you have an issue on the line, you run the risk of the breaker on the dimmer rack blowing instead of the breaker on the load side, especially when both breakers are rated the same. It is pretty much a crap shoot as to which one will blow first
.

This is where I would like to get some more input on. This seems to be the biggest problem. I had stated that I would use 15 amp double pole breakers and there would be 20 amp single pole breakers up stream of that. So there would be no crap shoot problem. As long as the breakers are lower than the breakers upstream. How is that wrong?

Will this "box" be designed, assembled, and tested by a UL Listed 1640 assembler? How does the theatre's insurance carrier feel about the use of a "homemade" piece of electrical distribution equipment?

I am not sure how to answer that. Other than it will not be. My TD has requested plans on anything I am proposing to build. It will probably be looked at by the people that will be upgrading the etc sensor rack system. The building is owned by the city so it is self insured. Maybe a city electrician will look at it as well. Believe me this will not be done in secret. This will be checked by several people.

Based on footers links your not saving any money at all by doing it the wrong way. I still don't understand why your so driven to use the dimmer rack for power after we've all told you it can't work.

I will take no for an answer if it is explained to me the reasons why. The reason why I am so driven is curiosity and education. If it is not safe I did not see the logic in checking the cost. Yes several people have told me that it won't work. I have changed my idea a little to see if it could work. I can only address the concerns everybody has and answer them. If I can't then I will feel comfortable in going in a more conventional direction.

In conclusion I had an idea that I thought would work. I am trying not to appear than I'm obstinate and I try to answer each question in a logical manner. I did not want to propose this plan to my TD unless I thought it was safe and cost effective. That is why I had brought this up in this forum to get some ideas and information. I am happy with all the responses I have gotten so far. The only thing that is left to ask is that if my current idea is safe and not to crazy of an idea. I hope I have answered some of the questions that were proposed earlier in this tread. And I hope I can get feedback on why it is unsafe. Thank you.
 
The fundamental problem with the approach of extracting 208V power from a Sensor rack is the circuit cannot be de-energized by a common breaker. End of story. No amount of wishful thinking or clever crafting can resolve that problem.

There are 2 locations in the rack where it might be possible to install a module with a common breaker that would span 2 phases. However, ETC does not manufacture such a contraption. Bodging something yourself invalidates any existing approvals. Consequently there is no UL or NEC approved way of getting a 208V circuit out of the rack.
 
Not to mention its not cost effective, nor should any tour ever want to use that system. I don't mean to sound rude but experience is useless if its been lessons learned wrong. I know of a head electrician of 25 years who doesn't know squat outside of flipping a breaker or changing a lamp.
 
And I hope I can get feedback on why it is unsafe. Thank you.

Here is that feedback:

1. The ETC Sensor dimmer rack is UL listed to feed only 120V grounded-neutral loads, not 208V loads. Connecting a 208V load to the rack violates the UL listing and the conditions of use for the product.

2. If you were foolish enough to add a downstream two-pole circuit breaker, common-trip to a pair of dimmer outputs on different phases, there is no guarantee of the coordination of the module breaker and the outboard breaker, especially since the outboard breaker is likely to be a thermal breaker and the module breaker is a fully magnetic breaker. You cannot guarantee that the outboard breaker will open first in the event of a fault. If a module breaker were to trip first, you have an unsafe condition at the load since one ungrounded conductor would remain energized.

3. The liability of constructing “home-made”, unlisted power distribution units is considerable. I suggest it is very unwise to head in this direction, since if there is a problem, the solution you are attempting to propose will not stand up to scrutiny by an AHJ.

There are many purchase or rental sources of listed portable power distributions that are designed to solve the problem you have described. I suggest you avail yourself of one of those sources.

Steve Terry
--VP R&D, Electronic Theatre Controls
--Member NEC Code Panel 15—USITT Alternate Representative
--Member, PLASA Electrical Power Working Group
--Member, PLASA Technical Standards Council
--Member, UL Standards Technical Panels 498, 924, 1008, 1340, 1691
--ETCP Certified Electrician
--ETCP Recognized Trainer
 
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The fundamental problem with the approach of extracting 208V power from a Sensor rack is the circuit cannot be de-energized by a common breaker. End of story. No amount of wishful thinking or clever crafting can resolve that problem.

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?
 
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?

Because somebody with a bit less knowledge attempting to trouble shoot the system, might not know that the single Sensor breaker feeding 1/2 of the load is the only breaker, thus won't de-energize the other half. The common trip breaker is idiot proof.
 
The ETC Sensor dimmer rack is UL listed to feed only 120V grounded-neutral loads, not 208V loads. Connecting a 208V load to the rack violates the UL listing and the conditions of use for the product
.

This maybe a part of electricity I don't understand. For example if I make 208v out of circuit 318 and 319 it will create a load of lets say 10 amps on each leg back to the 2 circuits to the dimmer rack. Now if I use them normally and plug 2 lights into them how is it different? I have not changed anything on the dimmer rack side.

2. If you were foolish enough to add a downstream two-pole common-trip breaker to a pair of dimmer outputs on different phases, there is no guarantee of the coordination of the module breaker and the outboard breaker, especially since the outboard breaker is likely to be a thermal breaker and the module breaker is a fully magnetic breaker. You cannot guarantee that the outboard breaker will open first in the event of a fault. If a module breaker were to trip first, you have an unsafe condition at the load since one ungrounded conductor would remain energized.

I did not know that a magnetic breaker and a thermal breaker would react differently. I would be buying parts for this box and I could make sure that they are also fully magnetic.

3. The liability of constructing “home-made”, unlisted power distribution units is considerable. I suggest it is very unwise to head in this direction, since if there is a problem, the solution you are attempting to propose will not stand up to scrutiny by an AHJ.

I thought I had addressed this. So what you said that must mean that even if it is checked by a city electrician that it does not absolve me from liability because I built it. Of course if what everybody said was true than a city electrician would never approve it. So it would not get built so no liability.

If a module breaker were to trip first, you have an unsafe condition at the load since one ungrounded conductor would remain energized.

I know that is a problem. Though I still don't know why. As you know that is what I am trying to address. Hence the full magnetic 15 amp 2 pole breaker. Also why is it an ungrounded conductor? I just want to say that I have learned so much more that when I started this post. I am still glad that I presented this idea so I can learn more about my craft.
 
Because somebody with a bit less knowledge attempting to trouble shoot the system, might not know that the single Sensor breaker feeding 1/2 of the load is the only breaker, thus won't de-energize the other half. The common trip breaker is idiot proof.

As I was thinking about this problem that is the only thing I could think of on why it would be wrong. The system would not fail and cause a electrical fire. I can't think of on how it could. If that is the case then everything can just be unplugged to be serviced you would not have to turn off the breakers. I don't know why it would have to be more idiot proof than that. If everything was hardwired in I could see it become an issue.
 
I am getting very frustrated reading this, I guess I just don't understand your aversion to doing this the "legal" and "Correct" way?
You are correct, it is very unlikely that the AHJ will allow you to use the home make box, but even if it were allowed, it shouldn't be.
(People, including electrical inspectors make mistakes)

There is literally no way to build this box to do what you want it to do legally, and without voiding the UL listing on the dimmer rack at the same time.

There is no way to ensure which breaker blows first, even if one is lower amperage, and the same type.

I also would suggest you show your TD this thread, so that He or She understands what is going on, and the downside of what you proposing.

In any case Please listen to Steve Terry, and many other who have posted in this thread.
Buy a 208v power distro. It is the only way to go in this circumstance.
 

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