Getting power? 50 Amps?
- Thread starterCharc
- Start date
Haha, are you insane? I'm no where near qualified to tie in with cams.
For the sake of answering the question, I'm prepared to be hypothetically electrocuted. We'll I'd have to hazard a guess that the first thing I'd connect is the ground, to make sure the hypothetical me is never the path of least resistance.
Good guess. Now the cool thing. New Panels like the one you posted a picture of, have an interesting safety interlock. you can't open the little cover till the previous lead is installed. Most < ok, a lot> of the newer disconnects out there also have gone to the new NEMA standard of having 2 < two > neutrals. As you observed earlierin a standard 3 phase camlock panel al three pahases are sharing a common nuetral. This new style panel releives some stress on that circuit. < and sells more cable, camlocs, and panels.>
In response to one thing mentioned earlier, Peter, This is not "sort of" getting into the realm of a "real" electrician. This is the realm of a real electrician. Tie-ins and disconnects should not be performed by anyone who is not properly trained and licensed. Most state have a MINIMUM requirement of being an LME < limited Maintenance Electrcian> license holder before you can even take the screws out of a panel to do a tie in. In Portland you are "supposed" to be an LME prior to connecting cam-loks into a company switch. Lets make it Very Clear children. Electricity can kill you dead. Even a 60amp sub panel in the woodshop has the ability to roast your eyeballs right outta your skull. As for cam-loks I once lost half of an EDI 48 touring rack because one of my "kids" from the shop decided to help out during an out. She just started disconnecting, the ground first, then the neutral........ Luckily it was only the pack that fried.
< I hated that pack anyway it weigh 600 pounds.> < But I didn't tell her that!>
Many of the installs are now going with a system that will not allow you to open the cap on the cam lok if the system is energized. There is usually a requirement now to have posted right there the proper connect and disconnect sequence.
Van's experience is a classic example of how to have a disaster. NEVER EVER REMOVE THE NEUTRAL FROM A HOT CONNECTION, THE SAME GOES FOR GROUND.
For the sake of education, when connecting, on a standard setup go from right to left, first connecting ground, then neutral then each of the hots, all with the power off.
to disconnect, power off, again typically going from left to right, disconnect each hot, then neutral then ground.
Sharyn
Van's experience is a classic example of how to have a disaster. NEVER EVER REMOVE THE NEUTRAL FROM A HOT CONNECTION, THE SAME GOES FOR GROUND.
For the sake of education, when connecting, on a standard setup go from right to left, first connecting ground, then neutral then each of the hots, all with the power off.
to disconnect, power off, again typically going from left to right, disconnect each hot, then neutral then ground.
Sharyn
So, in an example "from the world"....
A 24x2.4kW Sensor Rack and a 6x6kW Sensor Rack tied into a 400amp company switch. Tails to Tees to two short runs of feeder to the two racks. The cables had to be routed under the corner of a showdeck (with the cams right at the upstage edge of the deck--ie, not hidden by the deck).
SOMEHOW, something go put down on the neutral tee, and caused it to rotate just enough that it was completing the circuit but not "locked".
When there would be a lot of traffic at that corner of the deck it would wiggle the connection.
Our first indication that something was wrong was a twofer that melted like a cannon fuse. Then the lights on those racks all stopped working. I started metering power at the racks. At the 6kW rack: L1 to N was giving me ~200v, L2 to N was 60-80v, L3 to N was ~120v. N to G was ~80v. At the other rack things seemed fine, but nothing would turn on.
It took a while to figure out exactly what had happened--tech was still happening around us.
Disconnecting the neutral is not only VERY dangerous (potentially to people, and apparently twofers!) when the system is energized, it will cause lots of weird things to happen.
--Sean
I've seen many panels with the gound on the left, so I would disagree that it is "standard" to connect right-to-left
A safer way of putting it might be:
Connecting: Start with the ground, and work accross
Disconnecing: Start at the opposite end from the ground, and work accross, ending with the ground
-Fred
And some gear/boxes have soft tails....
Green/ground is ALWAYS connected first.
Then white/neutral
Then the three hot legs
Disconnect in reverse order. Then the panel layout is irrelevant.
--Sean
That's exactly what I was getting at with my earlier "test" question.
BenFranske
Member
A lot of the new company switches I see have no caps but have the connections behind a door (with a feed through on the bottom) which cannot be opened while the switch is on. Another interesting tidbit to remember is that the ground and neutral cams should be reverse gender from the hots so they can't be crossed.
That is up in the air, while it is a good idea in my book this would have to be a universal thing otherwise the amout of adapters needed will make this counter productive. WE are almost done with 3 pin DMX cable after 10 years, the move to flipped G+N might take twice that as the cost per conector is greater.
Yes, Van, thank you for clarifying that. The only part of this that is not treading into electrician's terratory is the connecting / disconnecting of cam. This can be done by a non-licenced electrician with proper training.
About the flipped gender ground / neutral, we recently found out that that is quite a standard practice "out west" according to several rental houses and distro manufacturers in our area, and most of the eastern seaboard uses all of one gender on a device. We found this out the hard way when a new distro we ordered came with the ground and neutral's genders reversed. We simply bought two "gender benders" and always keep them with that distro and run the rest of our equipment with all connectors the same gender on any given device.
About the flipped gender ground / neutral, we recently found out that that is quite a standard practice "out west" according to several rental houses and distro manufacturers in our area, and most of the eastern seaboard uses all of one gender on a device. We found this out the hard way when a new distro we ordered came with the ground and neutral's genders reversed. We simply bought two "gender benders" and always keep them with that distro and run the rest of our equipment with all connectors the same gender on any given device.
It seems to be an East coast/ West coast thing. Most of the lighting gear, on the East coast has H&N reversed. This has been the case for at least 10 years. There are already countless "turnarounds" floating around (and MMF or MFF tees can be used as well).
--Sean
JD
Well-Known Member
Beware a Floating Delta! Had this in a club in PA once. All three legs measured 120 volts to neutral.. 3 Phase Y right? Nope! A separate feed that handled air, it was a delta box (240 between hots) with no neutral tap on the transformer! (As compared to the tapped delta 120/120/208) When a leg was loaded, it would go to 0 and the remaining legs would go through the roof! (I had to climb the pole outside to figure this one out.) There was a second feed for another mains panel coming in that was standard 3 phase Y (120/120/120 208-208-208) So the tip off was the 120 to ground but 240 between legs and three legs in the box. Only one I ever ran across in 30 years! (BTW, I was using EDI dimmers, they seamed to laugh off the over-voltage! Shame they weigh more than a truck!)
Now, on to "Tapping fees." Never ran into this, even though I did a lot of work down in the Philadelphia theater district. (Schubert, Academy, Forest, etc.) I have to qualify that statement as they were union houses that billed the promoter directly, so there may have been billings I did not know about. Around these parts they are known as "Theatrical Disconnects" for road shows. There were some locations that would charge for a "House Electrician" which was generally the guy that would sit at the bar and watch you do it. My guess is this varies from state to state. The worst were the club owners that would point to 20 amp wall sockets as you were holding camlocks in your hands! Education of venue owners was always the hardest part for me.
To answer some of the questions posted on this thread, Three phase power uses the same size neutral because the power is happening at a different time on each leg with a phase lag between them. With an exactly balanced load, no current flows through the neutral. (This will never happen in real life!) As far as handling power, it's like rigging: If at first you don't succeed, don't do power taps! There is no room for error.
As far as rain goes, "Danger Will Robinson!" I know, we have all had to do them, but until they invent a 400 amp GFI, it will not be safe. As for the equipment, Cover the moving lights first! They may get wet, work fine, and then three months later fail!
Now, on to "Tapping fees." Never ran into this, even though I did a lot of work down in the Philadelphia theater district. (Schubert, Academy, Forest, etc.) I have to qualify that statement as they were union houses that billed the promoter directly, so there may have been billings I did not know about. Around these parts they are known as "Theatrical Disconnects" for road shows. There were some locations that would charge for a "House Electrician" which was generally the guy that would sit at the bar and watch you do it. My guess is this varies from state to state. The worst were the club owners that would point to 20 amp wall sockets as you were holding camlocks in your hands! Education of venue owners was always the hardest part for me.
To answer some of the questions posted on this thread, Three phase power uses the same size neutral because the power is happening at a different time on each leg with a phase lag between them. With an exactly balanced load, no current flows through the neutral. (This will never happen in real life!) As far as handling power, it's like rigging: If at first you don't succeed, don't do power taps! There is no room for error.
As far as rain goes, "Danger Will Robinson!" I know, we have all had to do them, but until they invent a 400 amp GFI, it will not be safe. As for the equipment, Cover the moving lights first! They may get wet, work fine, and then three months later fail!
When i was a young know it all, as opposed to now when I'm a Mature know it all, I hooked up a dust collector to a plug in our new shop. Fired up just fine, then I touched it and got the crap knocked out of me. Yup is was an old mechanical warehouse / metal working facility where they used a lot of heavy machinery, all of it delta. FYI now days most good electricians will mark an outlet or switch with a triangle to let others know it is a delta feed and not 3 phase 120. As a good measure, always check every hot to hot, and neutral to hot. They should be 240,240,240,120,120,120, for standard 3 phase 240/120 or 208,208,208,120,120,120 for a 3 phase 208 or motor feed.
Neutral to ground should be 0 if it's anything higher than 12v there is a good possibility that there is a floating nuetral, or reversed nuetral somewhere in the system.
I actually used a 400 amp gfci for the dive scenes in Men Of Honor , Since we were on a dock with a lot of lights and we had folks in the water,around the water etc.etc we had to have this little unit in-line with our Jenny. it was about 2x2x2.5 feet and weighed a ton!
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