Lights stay on even when power to rack is off. How?

Agree with Bill C . - You brought up the local switch in connection with a fixture that can be turned on and off normally but fed by two circuits. The whole two-circuit cause has to be before the switch, in this case the dimmer. It seems highly improbable in an SCR dimmer cabinet (as stated NSI Architectural dimmer from 20 years ago) that the dimmer feed and branch breakers could be off and still being fed by two circuits; and since it does dim normally it can't be fed by a secondcircuit after the dimmer.

And Ron - if you remove the front cover from a live breaker panel and meter the actual output terminals of the breakers themselves, you may expect to find voltage while a given breaker is switched on and you MAY expect to see the voltage fall to zero upon switching off the breaker. Some people will suspect a fault within thebreaker if the voltage remains present when the breaker is switched off when what they MAY in actuality be measuring is a combination of the voltage being supplied by the breaker coupled with voltage being back-fed to thebreaker's output terminal while it's switched on and the voltage being back-fed remaining on the output terminalwhen the breaker's switched off. This strongly points to an an inadvertent cross connection between load circuits from the same leg / phase amongst the circuits.


Wow....a good one. I would love to be there with my testers and hunt this one down.

Can't wait to hear what the problem really is.
@garyvp I can tell you from first hand experience it's . . . . . . . "interesting / relieving / richly rewarding when you eventually hunt it down to within a junction box above a very expensively finished ceiling."
Here's another puzzler for you:
There was / is a fairly spendy Crestron installation in the heart of downtown Toronto installed by one of the larger [All things to all people] factory authorized Crestron contractors.
I'll skip over the uglier legal aspects of "somebody else's problem" and proceed directly to my point.
A friend of many years became a then comparatively recently factory authorized Crestron dealer.
While making an exploratory site visit prior to bidding a new project within a building, he was asked would he mind looking at an existing installation elsewhere within the same building. The system's owners rep' led us to a small room containing a quite large collection of various Crestron modules, invited us to sniff the air then pointed to two modules which were the 'outcasts' from two previous visits by their then under contract maintenance company. Apparently a specific module had smoked and charred itself to death and was systematically, and symptomatically, replaced only to be found charred and in need of a third replacement. One factory original module next to its two replacements in two weeks with a third replacement / fourth module presently charred and dead within the rack enclosure. Crestron's anything but an upstart inexperienced company building to a low price point.
Quite the opposite. They've been charging top dollar for top tier gear for quite some years and definitely have a handle on what they're doing.
At some point, you'd think someone would've stepped back and figured they were treating the symptoms but not the actual root problem at hand. Here's the crux of the problem and it most emphatically wasn't Crestron's modules but careless installation of load circuit wiring external to the rack. When I tracked down the problem I felt honor bound to report it to Crestron but as the owners were contemplating legal action against their installation and maintenance contractors, my immediate supervisor suggested I keep my mouth shut and bask in the glory of having analysed the root problem. A few months later, I cold-called Crestron attempting to report my discovery and suggest they might keep their eyes open for a less than obvious loop-hole which could prove problematic in some cases of faulty mis-installations. If you've ever cold-called a company like Crestron and tried to suggest there's the tiniest of 'flies in their ointment' AND you're just some bozo they don't know calling from Canada . . . well . . . frankly they don't want to hear from you, they're so sure of themselves and their rigorously tested and approved products, it's beyond their comprehension that any bozo from the boonies could possibly have discovered any flaws. The fellow tersely explained ALL service was to be carried out EXCLUSIVELY by factory authorized technicians, which I personally clearly wasn't, and was about to hang up when I said: "Sorry! I thought you may want to learn of a potential fire hazard with one of your modules that a factory authorized tech' has routinely replaced twice in two weeks." Suddenly he was interested in hearing from me and noted my discovery.
Here's the bottom line:
In this series of dimmer modules, they offered the following amongst a great many others:
Modules that supply 120 VAC loads with 10 VDC contol.
Modules that supply 120 VAC loads with 120 VAC control.
208 VAC / proprietary control
Incandescent loads
Fluorescent loads
LED loads
You've got the notion, the range ran the gamut.
If you're supplying 120 VAC fluorescent loads with old fashioned dimmable magnetic ballasts employing 120 VAC control
AND an IBEW brother inadvertently confuses a black wire with a brown wire within a dimly illuminated junction box above a dimly lit ceiling during the 'rough-in' stage long before the Crestron rack arrives on site let alone before the installation's commissioning, you can end up with one poor little TRIAC suitably over-rated at perhaps an amp and anticipating being called upon to control perhaps 500 mill's, finding itself being called upon to control perhaps 5 of its 6 ballasts AND the full load current for its 6th fixture.
The clues to tracking it down:
The module was protected by let's say a 10 amp breaker supplying its input.
A higher rated TRIAC was employed to switch the steady-state mains power ON or OFF.
The lower rated TRIAC was only intended to provide the 120 VAC dimmed voltage for the ballasts' control winding.
When you supply both TRIAC's via the same 10 amp breaker, do not include lower on-board protection for the lesser rated TRIAC AND an installing "brother" inadvertently miss-identifies a black jacketed wire with a brown, you can keep right on smoking and charring poor little smoldering TRIAC's to death essentially as quickly as you're able to order and replace them.
To their credit: Crestron's boards were of excellent quality showing little damage considering the abuse they'd been suffering.
Have we communicated @garyvp? I suspect so and possibly you might explain this to the majority of our other posters.
It took some creative sleuthing to determine which fixture's dimmable ballast was cross-connected and the visible clue lay in which fixture would snap on vs. which would ramp up as if being supplied from a dimmer rather than what was essentially a non-dim.
Toodleoo!
Ron Hebbard.
 
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Brief update, on vacation for a few days so can't do further updating for a few days. Spoke with a company rep who indicated that there is no backup power circuit in this system. The circuits were originally pulled to a standard electrical breaker panel. At a later time a reputable electrical company added the dimmer system by interfacing the circuits at the electrical panel. My next move is to locate the original panel and try to discover how the extension was executed. Thanks for the helpful information!
 
Brief update, on vacation for a few days so can't do further updating for a few days. Spoke with a company rep who indicated that there is no backup power circuit in this system. The circuits were originally pulled to a standard electrical breaker panel. At a later time a reputable electrical company added the dimmer system by interfacing the circuits at the electrical panel. My next move is to locate the original panel and try to discover how the extension was executed. Thanks for the helpful information!
@Jim Murphy Have you anything further to report? Have you gotten to the bottom of this yet?
Toodleoo!
Ron Hebbard.
 
Yesterday were finally able to get back into the building for further research. We did, in fact, finally find a separate architectural breaker panel and two more dimmer panels. Without taking a lot of time, the original configuration of the facility had only breakers for the light fixtures in the Sanctuary. They were switched using a breaker panel in a location not near the actual Sanctuary but near the secretary's office for some reason. When the dimming system was installed two dimmer racks for the existing circuits were installed at a location on the level below the original switch panel. The additional three dimmer panels were installed under the Sanctuary on the other side of the building. Apparently no one remembered that the two dimmer panels were there so we were not told about them. After discovering the additional panels we were able to verify that everything is wired correctly and fully troubleshoot the defective control boards and firing cards. Please accept my sincere thanks for all of the feedback from those who posted. The information allowed us to more fully understand the possibilities and ultimately trace down the actual configuration. So, as it works out, it cost more for the evaluation and troubleshooting than the actual repair. At this point i am going to pull together a system drawing showing the locations of the devices and circuits so that there will be some actual documentation of reality. Again, Thanks. Jim
 
I wrote an update yesterday but don't see it here. So the answer is that there were two additional dimmer racks located in another section of the building. Once we discovered that a whole bunch of things became clear, not the least of which is that the system was wired properly albeit without proper documentation that we were given. I really learned a lot from all of you and the terrific troubleshooting procedures and suggestions. Glad I stumbled onto this group. Thanks all!
 
Do you mean the lights are not even fed by this panel? I thought the op contradicted that, that they did some testing and turned lights on and off, but at some point they all came on.
Bill, in actuality we thought we had all of the circuits identified to three panels and there was some reason to believe we understood the configuration. But now we see that there is a bad control board and firing boards and so we really did not have our understanding of the circuit paths correct. On the second trip we started by a more detailed tracing of individual circuits back to dimmers and then discovered we were wrong and the additional dimmers as a result. So maybe not the best practice in troubleshooting and too much taking the customer's information as fact. There were 24 dimmer channels in the three original panels and 24 channels that seemed associated on the console. What we found were 40 dimmers in total but a bunch of them were cot connected to a circuit. Sort of a perfect storm of bad info and assumptions coupled with the fact we had defective units which let us down the primrose path.
 
Well done!

That was a good 'Duhhhhhh' discovery....and the customer is always right.

I document, diagram and label everything, and label all breakers.....but no one ever looks at this stuff but me. Beyond using the breakers as our dimmer disconnects, no one has a clue to how it all works and nor do they care. That's why they invented TDs,
 
Perhaps you've discovered "the first source of perpetual free energy". I recommend you file a patent.
@robmerow @garyvp @Jim Murphy @ Greywyvern A quick similar tale of purportedly "perpetual free energy".
A friend of a friend of a friend was involved with pulling together ALL technical aspects of a 10 day Fringe Festival to operate simultaneously across four venues in the heart of downtown Hamilton, Ontario, Canada. Two of the venues were homes to long established amateur theatres with the third being the secondary space of a pro' venue in town. Thus, three of the four venues were some manner of functional theatres. The fourth venue was to be accommodated in donated premises which had most recently served as a downtown restaurant bar and tavern housed within a 10 story renovated office tower. When the space had been functioning as a licensed bar with cooking and serving facilities, it had operated on two floors with the bar on the lower of two floors and the "fine dining / dancing / Karaoke one floor above. As it occupied portions of two floors which had at a previous point in time been the premises of multiple tenants, the space had three services c/w three separate meters and the building's owner paid three electrical invoices monthly for these portions alone. One service was 3 phase 5 wire 347 / 600 volts and the other two were 3 phase 5 wire 120 / 208. The 347 / 600 volt service also fed a Delta / Wye step-down transformer for a third 120 / 208 volt panel. This is when I was asked if I'd visit, test and identify all breakers, receptacles, lamps, bar coolers, ice-cube makers, liquid and mix dispensers, yada, yada, etcetera. Check for reversed hots and neutrals, integrity of grounds, basically do a number on the place and leave them with several pages of accurate sketches and legible Sharpy on masking tape labels. Basically one 120 / 208 service did one floor. The second 120 / 208 service did the other floor. The 347 / 600 service ran the air conditioning and 347 volt fluorescents across both floors with its step-down transformer supplying a few 120 / 208 volt items the building's owner had agreed to pay for as part of his tenants leasing contracts.
Recapping: 3 sub services. 3 KW/Hour meters. 1 Delta / Wye step-down transformer and 4 breaker panels.
Unusual: Yes.
Basically: So far, so good.
Discovered a few 'cross-pollinated' duplex receptacles and a few instances of receptacles sourced via 14/3 copper in a commercial establishment where 12/3 would normally be our minimum gauge. Found some interesting memorabilia and electrical relics from the disco era but nothing too unexpected UNTIL we discovered the "perpetual free energy" duplex.
After a day and a half of methodical checking, we'd never discovered a source for our mystery receptacle. Included in the festival's gratis donation deal was one brief visit with the building owner's favorite installation and maintenance electrician. Upon his arrival, we were waiting with a 60 watt incandescent clip light plugged into the mystery duplex and our flashlights. We breakered off all loads and pulled all three main breakers. The place plunged into silent darkness and our flashlights let us see all three meters had stopped turning. The "perpetual free energy" duplex was the only power still standing. Everyone's best guess was it appeared to have been sourced via a run of 14/3 BX from a street level drive-through car wash but no one was willing to ask the folks leasing the car wash if they'd mind dumping their service for a moment. We all scratched our heads, stroked our beards, chuckled and traded war stories. I advised the self-professed amateur theatre electrical expert to avoid the receptacle and go with only sources we'd fully checked out. Heck no! This was in a great location for him, he could plug two cheap plastic power strips in and run most of his sound and lighting without having to string those nasty big 12/3 SO cables around the place. I allowed as to how this MIGHT appear to be a 'God send' BUT what was his plan in the event the "perpetually free" breaker should trip with no one knowing where to find it. I guess some people are born lucky as the amateur expert powered two plastic plug strips and a couple of cube taps for good measure from the "perpetual free energy" duplex for ten consecutive 20 hour days with nary a hiccup. I guess impetuous youthful exuberance must count for something after all. As a long deceased work-mate of mine used to phrase it: "It only works for 'them' because 'they' don't know it shouldn't."
Toodleoo!
Ron Hebbard.
 
I wrote an update yesterday but don't see it here. So the answer is that there were two additional dimmer racks located in another section of the building. Once we discovered that a whole bunch of things became clear, not the least of which is that the system was wired properly albeit without proper documentation that we were given. I really learned a lot from all of you and the terrific troubleshooting procedures and suggestions. Glad I stumbled onto this group. Thanks all!
The older I get, the more I realize the difference between "qualified" and "masterful" is documentation.

(yes, I deal with a lot of software)
 
The older I get, the more I realize the difference between "qualified" and "masterful" is documentation.

(yes, I deal with a lot of software)
@Chris Pflieger And that in and of itself Sir is a "masterful" illustration of a "qualified" qualification attained at the tender age of 42. Congratulations upon attaining this monumental milestone achievement at such a youthful age. [And learn to recognize when your leg is being pulled mercilessly by one of the nonsensical geezers of the site.]
More seriously, all the best @Chris Pflieger
Toodleoo!
Ron Hebbard.
 
Ha! I'm sure we've all encountered the pristine breaker panel with nary a mark on it.

In my field of software, the mantra (i.e. lie) of "good code documents itself" is rampant.


This reminds me I have some load schedules I need to update.
 

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