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

Discussion in 'Lighting and Electrics' started by Jim Murphy, Aug 12, 2017.

  1. Jim Murphy

    Jim Murphy Member

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    In troubleshooting an NSI architectural system about 20 years old for irratic behavior we found a bad control module. But, in the process we discovered something
    I do not understand. We had all lamps at full power and then proceeded to trip the breakers one at a time in an attempt to discover what lamps were on what breaker. The lamps in the corresponding circuits did NOT go out. We then turned off the main panel breaker to each dimmer pack. The lights still did NOT go out. How is this possible? The NSI tech, who admitted to not being an electrician, did not have an answer. He also said he had never heard of this situation in the past. Can anyone on this forum offer a suggestion? Any help would be appreciated.
     
  2. BillConnerFASTC

    BillConnerFASTC Well-Known Member Premium Member

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    Are they emergency lights? There would be a branch circuit emergency transfer switch between dimmers and lights, designed to transfer the lights to emergency power when the main feed is list.
     
  3. Jim Murphy

    Jim Murphy Member

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    That was our first consideration. At this point we have not seen as asbuilt only a prebuild which does not accurately reflect what we physically see. If there is such an arrangement, it is not anywhere in the vicinity as the dimmer racks. Each circuit leaves the rack individually leaving us to assume they go directly to the lamp locations.

    So my question now is, if you are right and it certainly seem that you are, how is the triggering to indicate power loss accomplished? What kind or manufacturer device should we see in circuit that is performing the switch?
     
  4. Amiers

    Amiers Custom Title of Awesomeness

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    The panel that powers the E-lights doesn't have to be next to the dimmers. You should look to other panels in your building to see if you can spot the not.

    You possibly could have a generator and not know about it.
     
  5. RonHebbard

    RonHebbard Well-Known Member Premium Member

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    @Jim Murphy Having read the other posts, let me suggest one other possibility which I've personally uncovered in the past five decades.
    TLDR warning FIRMLY in place:
    In one case this was 44 stories up in a brand new executive board room supplied by three phase 120 / 208 volts.
    The other instance was in the basement of someone's two story dwelling supplied by single phase 120 / 240 volts.
    In both situations, the root cause of the problem was identical in the following way:
    Inadvertently the hot conductors of two circuits had been mistakenly connected [Marretted] together such that either / both circuits effectively powered all of the related lamps in parallel. No "short circuits". No sparks or overheating of any kind. No symptoms of any problems other than you could turn off each and every breaker one at a time and the related lamps NEVER went out.
    In the first situation back in 1967, the homeowner had purchased his home used and lived in it for several years before wanting to remove the correct fuse and replace his basement ceiling lights as part of a basement recreation room upgrade. He removed every fuse one at a time and neither of his two basement lights ever went out. He solicited many opinions and chased down many red herrings but, in spite of investing much time and money, the mystery was never solved.
    One day a friend of a friend related the tale to me and the mystery nagged at me for several months. Finally, I just had to see this bizarre phenomenon for myself.
    Let me move this along.
    This was in the days when original contractors routinely roughed in lighting in unfinished basements as one ceiling mounted porcelain lamp socket at either end operated by a pull-chain / string hanging from each socket.
    You descended the stairs to your basement and pulled the first string, the light came on and you were happy.
    If you needed to go to the far end of the basement, you walked over there and pulled the second string. The second light came on and again you were happy. You reversed the procedure upon departing often cursing yourself upon ascending the stairs and realizing you'd left one of the lights on. That's when you'd come home from hockey practice and Dad would say "Go downstairs and turn the light off for me."
    I've digressed. My point was / is everything was working normally. The original home buyer hadn't paid for the deluxe upgrade that would have provided a switch at the top of the basement stairs for the basement lights. Only the wealthy paid for such frivolous upgrades in those days. Along came TV in the fifties and the early adopters had their sets in their living rooms. The crowd who just had to have the latest new gadget of the year, installed their new sets in the living room and moved their old set to the basement for Dad and his buddies to watch the ball game while Mom and the wives took over the parlor.
    By the time the home's present owners purchased the home, many renovations had taken place with wall mounted duplex receptacles having been extended from the existing ceiling lights' back-boxes. As each light was switched by its own pull chain, everything functioned normally. Wall receptacles were always live regardless of whether or not lights were on. Along came the present owners wanting to exchange the original porcelain socketed / bare incandescent lamps for the then new and modern cool white fluorescents and were totally bewildered to learn they could remove every fuse from their panel and their basement lights NEVER went off.
    Let's move this along a little faster:
    Showed up armed with flashlight.
    Homeowner removed each fuse one at a time demonstrating neither of the two lights went out.
    Single family dwelling.
    No neighbors on opposite sides of walls powered from alternate services.
    No emergency lights.
    No battery back-ups.
    No generators.
    No extension cords from the neighbor's exterior receptacle.
    Service entrance was a fused disconnect.
    Lit flashlight and pulled the main switch.
    Lights went off.
    Homeowner was surprised.
    Clearly lights were being powered from his immediately adjacent fuse panel as it was the only fuse panel supplied from his main disconnect.
    Pulled all fuses to remove the load and re-closed the main switch.
    With my flashlight still on, replaced the fuses one at a time while the homeowner and his family hollered from room to room and floor to floor dutifully noting what worked vs what did NOT work on each fuse.
    Imagine everyone's total awe when we discovered two fuses each supplying exactly the same items.
    Returned all of the fuses to their starting points and Dad gathered the family to collate and compare notes.
    Bid them au revoir and left them to compare notes.
    They offered money. I graciously refused, I was having just far too much fun debunking all of the various scenarios that had been suggested. At the time, I was still a lowly construction and maintenance electrical apprentice. It's not like I was a journeyman yet let alone a licensed electrical contractor used to showing up with my hand out. Nah! For me this was all just too much fun and great conversation for coffee and lunch breaks during my days on job sites.
    Armed with their new-found findings, the homeowners went back to two or three of their previous contractors and paid money to have them assess their now neatly detailed notes.
    The tales that came back down the 'friend of a friend' grapevine just kept getting sillier and sillier / less and less plausible / easier and easier to refute.
    Cutting to the chase:
    In those days it was common practice to run a circuit to an octagon box at one end of your unfinished basement.
    From that box, you'd run Romex up to a living room duplex and on up within the wall to feed a bedroom's overhead light and receptacles.
    You'd repeat this with two or three runs emanating from this same box / fuse and extending up to various points on the ground level and upper floor.
    At the opposite end of the unfinished basement's ceiling, you'd do exactly the same thing servicing the opposite end of the dwelling.
    Two fuses. Two circuits, covering the bulk of the dwelling's ceiling lights and wall receptacles.
    Range hoods were pretty much unheard of in working class neighborhoods.
    Washroom ventilating fans were luxury items beyond the aspirations of working class stiffs.
    The home's original purchaser MAY have gone 'hog-wild' and sprung for a separate circuit for his kitchen counter with a toaster and trendy new electric frying pan in mind.
    You may have a couple of 30 amp cartridge fuses for your hard-wired clothes dryer.
    Perhaps a couple of 40 amp cartridges for your hard-wired electric stove.
    Maybe you had a separate fuse for an outside receptacle for your car's block heater or battery charger but that was pretty much it. Thus it wasn't at all uncommon to find your entire home powered by basically two fuses.
    Neither the great explosion of electrical appliances; microwaves, home stereos, room air conditioners, ceiling fans, et al nor electric heating had occurred yet. Telephones had rotary dials and were hard-wired to the wall with 6' cords.
    Times were radically different and total electrical loads per dwelling far, far less.
    My grandmother's two story home was originally supplied by a single phase, two wire, 30 amp main service: One hot. One neutral. Overhead from the street, through a simple weather-head, through a hard-wired / non-socketed single phase single leg meter and directly on to an open porcelain block holding two [Count 'em 2] 15 amp twist in fuses.
    Times were definitely different.
    Getting back to the home owner with the mysteriously powered lights:
    Over the years, through the course of several previous owners, the two circuits [The circuit for one end of the home and the circuit for the opposite end] had become connected together within the dwelling. As luck would have it, both the circuits in question were sourced from the same side / leg of his single phase 120 / 240 volt panel thus no "shorts", no sparks, no flames, no apparent problems.
    True, you now had 14 gauge / 15 amp wire fed by effectively 30 amps but everything appeared to be normal and functional until they inadvertently tripped over the fact that they appeared to be in possession of mysteriously powered lights.
    Fast forward roughly four decades to a 44th floor executive board room in the heart of downtown Toronto.
    Include a fabulously huge board room table seating 24.
    Add fancy A/V, HUGE 3 X Barco PJ's, four PTZ cameras that descended from the ceiling and automatically tracked the various executives as they were recognized by the 'chair'. Indirect and direct CFL and incandescent lights, dimmers, computer controlled, motion sensed and IR controlled up the wazoo.
    Basically a bigger client with deeper pockets being taken advantage of by an even greater number of higher class contractors.
    Root of the their problem: EXACTLY THE SAME with the ONLY difference being a 3 phase 120 / 208 volt service this time coupled with the errant connection being within a junction box above a very fancily finished ceiling.
    The client was armed with documented data from the room control systems computer logs when they brought in their lawyers and cheerfully paid my boss's invoice.
    I won't go into the myriad of red herrings postulated and presented to either the original home owner or the bank in downtown Toronto but I'll cheerfully entertain and refute all comers.
    I'm not suggesting this is @Jim Murphy 's problem, just throwing it out there as one more plausible possibility to consider.
    I did provide a TLDR warning.
    It's lunch time here.
    Toodleoo!
    Ron Hebbard.
     
    Last edited: Aug 12, 2017
  6. BillConnerFASTC

    BillConnerFASTC Well-Known Member Premium Member

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    I did assume this was a place of assembly - an auditorium - and that if 20 years old probably incandescent lamps on dimmers, and that they did dim.

    The branch circuit transfer panel could be remote. There would be a sense or reference line - circuit-which basically holds the transfer relays on the normal or dimmer output side. Power fails, and the relay close on the emergency side. Its been done different ways - some correct and some not per code - so hard to say what was done in your space. And it could be something else.

    The emergency side could be fed by a generator, an inverter (big battery), or some other source that was deemed "emergency", so could be harder to track down.

    First thing - you said you tripped the breakers then the feed. Try resetting and running lights down on dimmer as you normally would. When lights are off, see if the individual breakers or the feed causes the lights to come on - but turn off and if no action turn on and go to next. I think narrowing which action causes them to be powered will help trouble shoot.

    Another thing you could do is see if there is power at the dimmer output - a meter or tester on the output breaker.
     
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  7. Jim Murphy

    Jim Murphy Member

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    The scenario you suggest where the lamp circuits were wired using 2 hot feeds was my first concern. The installation is very professional but, the dimmer system was clearly installed at some time after the building was completed. Some of the circuits were installed with construction but a number were installed most likely when the dimmer panel was installed. Another reason for concern is that all the circuits in the dimmer system remained at full power after the breakers were tripped. If the facility was somehow configured for emergency power it does not seem reasonable to configure every fixture for that function, only enough lamps to provide light yo exit the building not to complete a service.
     
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  8. Jim Murphy

    Jim Murphy Member

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    The facility is a medium size church building that is probably 30 to 40 yrs old. The dimming system was added about 20 to 25 years ago. We were doing our troubleshooting late in the day on Friday afternoon so we were unable to do any research on the configuration as we made this discovery as we're were shutting things off to leave. Your suggestions are very helpful and we will implement then on the next visit. We discovered that one of the main control units was bad causing the presenting problem which was unsolicited strobing of one of the circuits and intermittent self powering of the same circuit. There appears to be some failing firing boards as well but not necessarily connected to the bad control board. We will correct those issues as a matter of maintenance. I guess I am trying to ultimately determine if there is a wiring issue that needs to be corrected. After all it has worked, as far as I know, well until now. If there is no safety or damage concern with how it is wired then no harm no foul, let it remain as it is.
     
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  9. RonHebbard

    RonHebbard Well-Known Member Premium Member

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    @Jim Murphy This is one of those situations where on one hand, I want to delve into it, while on the other hand I hate the shot-gun approach of throwing out plausible scenario after scenario with zero ability from my distance to actually conduct any meaningful tests or make any first hand observations. That said, I'll continue to, in effect, scatter bird-shot (As duck hunters would phrase it) at your situation. Please excuse the disorganized randomness of my approach as I'm long past tired and hurting for sleep. Herewith my thoughts in random order as they occur.
    As @BillConnerFASTC suggested: Back-up power sources and methods of load transference can, and do, take many forms. I'll quickly glance over this by hitting two extremes from personal experience and suggest options run the gamut from one to the other.
    At the high-end you find installations where the back up is total x three in the sense that any one of the sources is conservatively capable of handling the entire needs of the installation / building / hospital / military / national defense. Think large V-12 diesel driven generator capable of handling 100% of the installation's demands while the generator is loaded to only 80% of it's capacity. Now that you've some notion of the generator, realize there will be three identical units in a row with the P. Eng's plan being one can be providing for your full power needs while another is being stripped down for regular maintenance and there's still that third unit sitting right there with block heaters, et al, keeping it fully ready to serve as back-up for the unit that's carrying the load. In installations at this level, when the installation is operating from its normal power source, they don't let the three generators sit there going to rot nor do they let them idle sans load. To the contrary; one of the three will be down for regularly scheduled maintenance procedures while the other two are operated for one or two hours per day purely to keep them active. Of course they want to test run the generators under load so they're either doing regularly scheduled seamless transfers with full phase synchronization of the outputs or powering "dummy" loads. [I REALLY hate to be skipping over the details.] In one such installation, their test loads (for lack of a better term) consisted of selling power back to our provincial / national power grid. As previously stated, installations such as this are at the extreme high end.
    The same 3 to 1 approach is extremely common in the 'pump and fan' industries where it's not at all uncommon to find three civic sized sewage pumps, three massive exhaust fans or three huge air conditioning compressors with any one of them designed to handle the maximum anticipated design needs.
    At the bottom end of the scale you've got gel-cell powered exit signs with a couple of lamps attached, sized to provide illumination for 30 minutes before rapidly dimming to a glow.
    I've NEVER placed a bet of any kind in a casino in my life. My biggest "gamble" has been sleeping daily in a guest room for free while toiling in a third level basement overnight. If / when you're gambling in any of the serious casino's, certainly any of the several I've worked in in North America, not pulling your focus from your gambling is their HIGHEST priority. If the sky were to fall outside their building, they wouldn't want their patrons to be aware of it in the least. To that end, the UPS inverters tucked out of sight in casinos are amongst the largest you're ever likely to encounter and the rows of 'large refrigerator sized' battery cabinets go on forever. I'll digress briefly. You may think a 96 x 2.4 KW dimmer rack is a reasonable size rack of dimmers. It may be but a lone rack pales in comparison when walking through a rack room housing 27 similar racks and then realizing there's a second dimmer room at the opposite end of the complex housing another 27 racks. When you appreciate there are (in one case) at least fifty-four 96 x 2.4 KW racks devoted to the myriad of individually controlled loads in ONE SHOWROOM, you rapidly realize you're 'not in Kansas anymore'.
    Let me tie this back to your situation.
    No matter how "professional" an installation may be, every now and again inadvertent errors can / may / do creep in.
    Aside from safety code aspects, 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 the breaker 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 the breaker's output terminal while it's switched on and the voltage being back-fed remaining on the output terminal when 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. Optimistically the two cross-connected circuits are sourced from within the same panel though this may not necessarily be the case.
    Rather than starting from a position of "normality" and switching breakers off individually one at a time, you're often better served by beginning with all the load breakers switched off then turning them on and documenting their loads one breaker at a time before turning a given breaker off and proceeding to the next breaker.
    The oddities are near limitless. You may think you're looking for a cross connection between lighting circuits when you may discover a live duplex receptacle circuit inadvertently connected with one of your dimmed or non-dimmed lighting circuits. Sometimes it can even be even more bizarre when you find one phase of a 208 volt dual or triple phase load inadvertently interconnected with one of your lighting circuits. Switching off a three pole common trip breaker only to find a back-feed on one of its output terminals that you eventually trace to a circuit powering a wall clock or light in a broom closet. I read @BillConnerFASTC as suggesting there was something unique about a place of assembly compared to a single family dwelling basement or 44th story board room. I guess my counter-point is Edsel Murphy's efforts know no bounds. Inadvertent inter-circuit electrical oddities can, and do, occur across a broad spectrum of installations.
    I talk too much when I'm beyond tired and I appear to have the same symptom / problem with my typing as well.
    Toodleoo!
    Ron Hebbard.
     
    Last edited: Aug 13, 2017
  10. BillConnerFASTC

    BillConnerFASTC Well-Known Member Premium Member

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    It does seem if it dimmed normally the fixture is unlikely powered by two circuits. It's not the spst pull chain.
     
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  11. JonCarter

    JonCarter Active Member

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    My thoughts, too. What happens to a dimmer if dimmed to "0" when line voltage is applied to its output from an external source? (Would still dim, as resistance dimmers are usually in the neutral, REALLY bad for an autotransfromer, ??? for an electronic.)
     
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  12. RonHebbard

    RonHebbard Well-Known Member Premium Member

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    @Jim Murphy @BillConnerFASTC @JonCarter @derekleffew or @gafftaper
    Jim; Are you any closer to resolving your issues and please keep us up to date on your progress.
    Bill; I must've missed the inclusion of any Single Pole Single Throw pull chain fixtures in the OP's specific situation.
    Jon; I too would be very interested in any discussions regarding what happens when cross-connections from other sources are inadvertently brought back and superimposed upon the outputs of various types of dimmers.
    Herewith a few sub topics for our latter point [Which Mods may wish to move to a new post]:
    a; The return is from another circuit within the same panel and with the same synchronous zero crossing point.
    b; The return is from another dimmer.
    c; The return is from a non-dim [often termed "air gap"] mechanical relay rather than an SCR, TRIAC or IGBT.
    d; Further discussions upon the effects with various types of dimmers such as:
    1; Resistance dimmers.
    2; Saturable core dimmers.
    3; Magnetic amplifier dimmers.
    4; Autotransformer / VARIAC dimmers.
    5; Dual SCR dimmers.
    6; TRIAC dimmers.
    7; IGBT dimmers.
    8; I suspect we can skip over thyratron and brine tank dimmers.
    e; Circuits intentionally involving the simultaneous use of dimmers in both the hot legs AND the neutrals of each load circuit.
    This latter situation was very popular when "Disco was king" and specific manufacturers were introducing 'cool new tricks' in which their various loads were connected 'MATRIX style' such that fully turning on the neutral dimmers and chasing the 'hots' resulted in vertical chases while reversing the situation by fully turning on dimmers in the 'hots' and chasing the neutrals resulted in horizontal chases. As bizarre as this sounds in today's times, this was considered somewhere between "Rocket Science" and the effects of poltergeists at the time.
    f; The return is from an independent / non synchronous source such as:
    - i; A generator
    - ii; An inverter / battery sourced UPS.
    Derek or Gaff; Perhaps you'd be interested in moving these latter points to a new thread to further explore issues raised by Jon.
    A penny for your thoughts, perhaps as high as a deflated Canadian Looney?
    Toodleoo!
    Ron Hebbard.
     
  13. BillConnerFASTC

    BillConnerFASTC Well-Known Member Premium Member

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    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 second circuit after the dimmer.
     
  14. RonHebbard

    RonHebbard Well-Known Member Premium Member

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    @BillConnerFASTC Exactly as I recall Bill and, I agree, not directly relevant to the OP's specific situation.
    Let me toss another consideration into the mix: [While I'm taking the 'shot gun / bird shot' approach which I so detest doing without direct knowledge of the specific installation.]
    Consider dimmer racks or packs which include both a single breaker in series with each dimmer's input and multiple [lesser rated] load breakers sourced from each given dimmer's output as often the case [Speaking in terms of North American 120 volt dimmers as opposed to 230 or 240 volt dimmers in other countries] when a 50 or 60 Amp breaker provides power for each individual 6.0 or 7.2 Kw dimmer and four to six single pole, non-common trip, 15 Amp breakers are provided for the protection of 14 or 12 gauge copper or aluminum load wiring. Inadvertent cross connections between circuits come into play once again.
    As I've suggested to Mods within another post, possibly they might consider spinning this off to a new thread devoted specifically to these concerns raised by @JonCarter as I too feel they're well worth the investment of our collective time.
    Always good chatting with others who've appreciably more than 'half a clue / clew'.
    Toodleoo!
    Ron Hebbard.
     
  15. Lekolite48

    Lekolite48 Member

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    Are you absolutely sure you've located all the dimmer packs/racks? This sounds like there may be another hidden dimmer somewhere that may be fed from the same source. Possibly added after the main system was installed?
     
  16. BillConnerFASTC

    BillConnerFASTC Well-Known Member Premium Member

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    I guess in the future, the question should be, how many suggestions will the people on the forum offer? Assume at least 5 from Toodles to begin with.
     
    Last edited: Aug 16, 2017 at 3:23 PM
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  17. Amiers

    Amiers Custom Title of Awesomeness

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    I'm still with Bill on this one there is some sort of other source that is feeding the lights.

    And Ron offers walls of suggestions lol. I sometimes have to switch to my iPad because my finger gets arthritis from swiping reading swiping.
     
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  18. garyvp

    garyvp Active Member

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    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.
     
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  19. Van

    Van CBMod CB Mods Premium Member

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    I'm voting for the fact that there is a separate, Architectural panel, as yet undiscovered.
     
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  20. BillConnerFASTC

    BillConnerFASTC Well-Known Member Premium Member

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    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.
     

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