Electrical Question

[soundguy99]

Hey guys,
I have a quick question for some of you more experienced lighting technicians.
I have been slowly going through allot of our cables in our lighting system, and slowly replacing all of the old connectors.
The connectors, are a 20 amp 120v/240V 3pin Twist lock style connector. Says Nylon on the connector.
I know that the "L" blade is the ground but I am not sure about the other 2. Which is Hot and Netural.
Their both the same size, and looking at the back, their is an X & Z marking marking the 2 pins.
I have also read that in a 240V configuration, Both X and Z are HOT.
Now, we have a Stand C21 System, 2.4KW Dimmers.
So I would imagine that would be a 240V system right, which would mean both the X & Z would be HOT, and as long as I get the ground right it shouldn`t matter which wire goes to which terminal right?
I am going to check some of the other connecters as well , but I thought I would ask some of the veterans here, to make sure I am on the right track,
Any help is appreciated,
Thanks,
soundguy

 

[derekleffew]

...The connectors, are a 20 amp 120v/240V 3pin Twist lock style connector. Says Nylon on the connector.
I know that the "L" blade is the ground but I am not sure about the other 2. Which is Hot and Netural.
Their They're both the same size, and looking at the back, their there is an X & Z marking marking the 2 pins. ...

If all you say above is correct, your connectors might be L11-20, but totally wrong for your application (should be L5-20). Dual-voltage connectors are not NEMA-approved and have been being phased-out (get it? phased out!) since the early 1980s. The TLGO is the last of these and very close to being obsolete. See also this thread http://www.controlbooth.com/threads/wiring-extension-cables.35789 .

I can find no 3pin 20A twist connector that meets all of your criteria: One "hooked" blade. Other two the same size. Labeled X & Z.
Are the blades/terminals both the same color? Brass, silver, or copper?

See if you can find your connector on the attached chart, and let us know.

 

[Scenemaster60]

Sounds to me like you have what Derek calls the TLGO (Twist-lock ground out) connector. These came on the scene in North America in the 1960s and were gone on new installations by the mid-to-late 1970s. They can still be found in large, reputable houses in the US. I know of one in St. Paul, MN built in 1970 that has over 300 receptacles and instruments with this connector. To be honest, you never know which is the hot and which is the neutral. In a recent seminar that I attended led by two well-known and respected master electricians in the Twin Cities reported that they often found the hot and neutral interchanged between X & Z WITHIN THE SAME PLUGGING BOX when these connectors were used!

For traditional incandescent fixtures this does't present an operational issue and with a little common sense these are quite safe for that application. The trouble comes in when you start using these circuits on non-dims for LED or moving lights. In that case you just need to carry a meter and check EVERYTHING before you plug in.

 

[BillConnerFASTC]

I have also read that in a 240V configuration, Both X and Z are HOT.
Now, we have a Stand C21 System, 2.4KW Dimmers.
So I would imagine that would be a 240V system right, which would mean both the X & Z would be HOT, and as long as I get the ground right it shouldn`t matter which wire goes to which terminal right?
soundguy

Stop right here please. The arrival at "...240V system..." from "...2.4KW Dimmers...." says to me you should not be doing electrical work. Red flag. I am fairly confident the dimmed stage lighting circuits are 120 volts, but p!ease don't service equipment you don't understand as even your sincere and best intentions won't always save us.

 

[danTt]

If all you say above is correct, your connectors might be L11-20, but totally wrong for your application (should be L5-20). Dual-voltage connectors are not NEMA-approved and have been being phased-out (get it? phased out!) since the early 1980s. The TLGO is the last of these and very close to being obsolete. See also this thread http://www.controlbooth.com/threads/wiring-extension-cables.35789 .

What about Stage Pin Connectors? Why are those allowed to be dual voltage still?

 

[derekleffew]

What about Stage Pin Connectors? Why are those allowed to be dual voltage still?

Stage pin 2P&G are not NEMA-rated. Also,

1. The ANSI E1.24 standard for stage pin connectors requires that the connections to the connector are
--Ungrounded conductor (hot)
--Grounded conductor (neutral)
--Grounding conductor (equipment ground)

2. The 20 amp pin connector is dual rated 125/250V. However, (1) above applies to all voltages. So the only place that the connector could be used at voltages higher than 125V is in 230/240 markets where the neutral is still connected to one of the pins.

3. The UL489 connector standard now references E1.24 for stage pin connectors.

4. A stage pin connector is not rated to carry three-phase power under any circumstances.

ST

-----

Sounds to me like you have what Derek calls the TLGO (Twist-lock ground out) connector. ...

You may very well be correct. OP's description of " 'L' Blade" caused me to think of "ground in" devices. If indeed we are talking about TLGO, the "hook toward hot" meaning the blade closest to the bend/nub of the ground applies, although this is by no means a universal standard. Was the TLGO once popular in Canada?

-----

I also must concur with @BillConnerASTC above; @soundguy99, find yourself a Qualified Person, one who can meter your outlets and possibly open a box to see if "hook-to-hot" applies to your venue. And now that you've gotten us all curious, post a picture of one of the plugs in question.

 

[JD]

When I first got in to lighting (Late 60s early 70s) these connectors were all over the place with no good description of wire designation. My own rule of thumb for 120 volts was based on the three phase designators: Phase A=X, B=Y, C=Z. Since "X" was phase "A", that was my first choice for the hot. The distorted pin (tab out, or L shape) was ground. The remaining pin was Neutral. As I said, it was "my" system, and therefore was only valid on my equipment. (But it made sense to me!) In any case, there was no protection for plugging into an outlet that may have been 208/240 with the second hot connected to "Y." As such, I was happy to see its (sort of) demise. At the time, we only used these for accessory power for non-dim applications, and used on a roadshow that made no use of local outlets.

Added note: I remember them being X,Y not X,Z but then again that was a long time ago!

EDIT: Just looking over the non-NEMA section of the chart derek posted and remembering what a mess it was. "3 wire grounding AND non-grounding" yea... that's clear

 

[soundguy99]

Sorry in the delay in replying,
but I still wanted to thank you guys for your comments.
First off on the connector its labeled 20 amp 125V/250V not 125V/254V sorry that was a type-o.
As far as the connector itself yes it is a twist lock, liike the L5-20's. Only this one has the blade turned out. Its an old theater so all of our older electrics and floor pocket plugs have the blade turned out.
Also I have gone through our connectors and we have a bit of everything including the Lexington L5-20's as well as hubbels and even 30 amp plugs mixed. Like I say its an old theater.
I also did take a meter to it, and found that yes your right it did measure 120V between Ground to one of the other blades. In fact the blade that is away from the bend of the ground blade.
Obviously I am stillll going to double check with the techs who installed the system, just to make sure, but its still good to do the home work and get a good understanding how the system is wired.
Even continuing to clean up around the place going through connectors, the little conversation here will make me pay more attention to the connectors, and how everything is wired.
Thanks again,
soundguy