Author Topic: How's this for ironic???  (Read 545 times)
wide-lite 1000
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How's this for ironic??? « on: September 09, 2019, 07:52:34 PM » Author: wide-lite 1000
A Columbus City School building received est. 150 K in fire damage from the LED conversion they did to save money !  

  https://abc6onyourside.com/news/local/columbus-city-schools-to-vote-on-150000-needed-for-fire-damaged-school

 In a way, it's kinda funny !
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Re: How's this for ironic??? « Reply #1 on: September 09, 2019, 10:37:30 PM » Author: fluorescent lover 40
Interesting! Wonder how it could be the ballast though? Maybe it was a magnetic one?
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Re: How's this for ironic??? « Reply #2 on: September 10, 2019, 12:52:15 PM » Author: Ash
A ballast failure in a proper FL luminaire would never cause a fire since it is enclosed inside the metal luminaire body. But the plastic enclosures of LED drivers of most LED luminaires (that gets tucked in ceiling space) or plastic endcap of a LED tube (that can drip onto papers in the room) doesn't stop fire spreading if the circuit board inside caught fire

Last time i know of when FL caused a fire was in Zim building in Israel in the 1950's. And that involved FL luminaires with open back design (not meant for installation on flammable ceilings), installed on chip board ceilings (a material which in itself was allready then banned for use in construction due to flammability) and a stuck starter

With as much as icepacks with falling covers and burning ballasts in the 90s were scary, i never heard of a fire from one of them
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Re: How's this for ironic??? « Reply #3 on: September 10, 2019, 03:36:44 PM » Author: wide-lite 1000
Knowing the city , It probably didn't have the ballast cover installed , or they had insulation or something on top of the fixture .
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Re: How's this for ironic??? « Reply #4 on: September 10, 2019, 04:22:38 PM » Author: RyanF40T12
Actually there have been many fires of the years from fluorescent ballasts overheating and igniting ceilings and walls from the heat alone.   
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Re: How's this for ironic??? « Reply #5 on: September 10, 2019, 04:24:40 PM » Author: Lumex120
There was a case in my area a few months ago where a fluorescent light ballast apparently started a fire in a kitchen. Fortunately it didn't do any serious damage.
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Re: How's this for ironic??? « Reply #6 on: September 11, 2019, 11:38:32 AM » Author: Ash
Is it the case that the ballasts drip burning tar that can ignite something outside of the luminaire body ? I dont think it is possible for a "dry" ballast to overheat to the point of setting fire to something through the luminaire metal body (that spreads the heat over bigger area and acts as heatsink)
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Re: How's this for ironic??? « Reply #7 on: September 11, 2019, 09:16:17 PM » Author: Ash
For the isolation to melt back to the ceiling means that it melted past the wire nuts connecting the ceiling wiring with the ballast wiring. That cannot happen by heat conduction - only by arcing at the wiring

And this indeed is only possible when the breaker is failing to trip or extremely overrated for the circuit, to the point that it won't trip to an arcing short between Phase/Neutral or Phase/Earth
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Re: How's this for ironic??? « Reply #8 on: September 12, 2019, 06:32:32 AM » Author: sox35
You exceed the ampacity rating of a wire and it begins to heat up and you exceed the ampacity drastically and it can melt the insulation. That is why the NEC has ampacity ratings for sizing conductors and coinciding breaker/fuse sizes for that conductor. 
Ampacity, I love it..! If that isn't a proper word, it should be  Cheesy
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Re: How's this for ironic??? « Reply #9 on: September 12, 2019, 08:52:15 AM » Author: sox35
It's still a wonderful word..! Over here we'd just say current rating.
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Re: How's this for ironic??? « Reply #10 on: September 12, 2019, 01:30:54 PM » Author: Ash
In electrical engineering in the area of design of power systems (thats my area mostly) in Hebrew, we talk about current rating as there isn't specific term for ampacity. But we do in fact mean by the same term either the "rating" meaning (for things that are rated by the manufacturer) or "ampacity" meaning (for things where it is more of empirical data, like how much current can a conductor handle with a specific temperature rise)

And sometimes we also talk about current density (when trying to evaluate the current carrying capability of conductive parts that dont have specs other than size)



All cases mentioned here in which the conductors in the wall became oven heating elements, are not possible with properly working circuit protections. So it is not the ballast's fault. Ballasts and other electrical components are expected to sometimes fail short circuited

There is only one other case about which i might think that would cause wire overheating like that, and it is, if the Earth wire becomes a path of some stray currents (say between an appliance connected to remote Earth source, such as plumbing or data cables), or a Neutral to Earth short carries Neutral current of upstream loads in a broken Neutral condition

The latter though can be protected against with a GFCI

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Re: How's this for ironic??? « Reply #11 on: September 12, 2019, 04:24:44 PM » Author: AngryHorse
And this is EXACTLY why when you do an LED conversion you rip out the control gear and wire LED tubes direct like the manufacturers guidelines!!
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Re: How's this for ironic??? « Reply #12 on: September 13, 2019, 06:05:35 AM » Author: Ash
Sharing a Neutral between circuits is very bad thing to do even if it is allowed

It is dangerous not only due to ampacity but danger to anyone who would be working on the circuits, and unaware of the little secret. He will flip off the breaker for one of the circuits, probe all conductors and see that they are not energized, open a connection on the Neutral and once he does, some wires will become live through the load of the other circuit, which is still on

I was talking about other situation though :

You have an 15A circuit (with 15A breaker on the Phase), which is fed from a sub panel

Case 1 : If in your systems Neutral and Earth in the panel go to 2 separate busbars (like here in 230V hemisphere), then let's assume that a short happened between Neutral and Earth in the appliance on the 15A circuit. There is no GFCI on the circuit

Case 2 : If they go to the same busbar (like what i seen in some pictures online ?), then let's assume that the appliance is intact, but it also connects Earth from the receptacle to a remote Earth. For example a water heater connected to metal water pipes, a TV connected to cable TV (that goes to the cable TV network and is Earthed over there), etc

Any of the cases can exist for years without anyone noticing. Case 2 isn't even an actual fault of any equipment, just bad installation practices

One day the Neutral in the feed to the subpanel breaks

Now the Neutral current from other loads of the sub panel (which can sum up to way more than 15A), can go in one of the ways :

In case 1 : from the Neutral busbar in the panel, through the Neutral of the 15A circuit, the short, back to the panel through the Earth of the 15A circuit, Earth busbar in the panel, and Earth connection

In case 2 : from the Neutral+Earth busbar in the panel, through the Earth of the 15A circuit, appliance, and remote Earth


GFCI on the circuit can prevent case 1 - it would catch the Neutral current (which does not exist on the Phase) and trip

Case 2 can only be prevented by breaking any remote Earth connections - using nonmetallic pipes (at least a short part of the pipe to break the dead short connection), using isolator modules on the TV coax, using optic fiber (and not ethernet) to connect network between 2 buildings, etc
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wide-lite 1000
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Re: How's this for ironic??? « Reply #13 on: September 13, 2019, 08:23:55 PM » Author: wide-lite 1000
Sharing a Neutral between circuits is very bad thing to do even if it is allowed

It is dangerous not only due to ampacity but danger to anyone who would be working on the circuits, and unaware of the little secret. He will flip off the breaker for one of the circuits, probe all conductors and see that they are not energized, open a connection on the Neutral and once he does, some wires will become live through the load of the other circuit, which is still on

I was talking about other situation though :

You have an 15A circuit (with 15A breaker on the Phase), which is fed from a sub panel

Case 1 : If in your systems Neutral and Earth in the panel go to 2 separate busbars (like here in 230V hemisphere), then let's assume that a short happened between Neutral and Earth in the appliance on the 15A circuit. There is no GFCI on the circuit

Case 2 : If they go to the same busbar (like what i seen in some pictures online ?), then let's assume that the appliance is intact, but it also connects Earth from the receptacle to a remote Earth. For example a water heater connected to metal water pipes, a TV connected to cable TV (that goes to the cable TV network and is Earthed over there), etc

Any of the cases can exist for years without anyone noticing. Case 2 isn't even an actual fault of any equipment, just bad installation practices

One day the Neutral in the feed to the subpanel breaks

Now the Neutral current from other loads of the sub panel (which can sum up to way more than 15A), can go in one of the ways :

In case 1 : from the Neutral busbar in the panel, through the Neutral of the 15A circuit, the short, back to the panel through the Earth of the 15A circuit, Earth busbar in the panel, and Earth connection

In case 2 : from the Neutral+Earth busbar in the panel, through the Earth of the 15A circuit, appliance, and remote Earth


GFCI on the circuit can prevent case 1 - it would catch the Neutral current (which does not exist on the Phase) and trip

Case 2 can only be prevented by breaking any remote Earth connections - using nonmetallic pipes (at least a short part of the pipe to break the dead short connection), using isolator modules on the TV coax, using optic fiber (and not ethernet) to connect network between 2 buildings, etc
The building I work in (built in 1993?) has shared neutrals in the lighting circuits. I was changing out a high bay fixture (277v) and got LIT UP by the neutral !
The junction box at this particular light was rather crowded and I didn't feel comfortable doing it live so we killed the breaker to that particular set of lights and while hooking up the new one ZAP ! turns out there were 3 circuits sharing that neutral ! 277 HURTS !  Apparently that practice isn't legal here anymore but doesn't mean there still aren't old systems that still have it .
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Re: How's this for ironic??? « Reply #14 on: September 14, 2019, 01:59:56 PM » Author: Ash
There allways may be systems from before the code was in effect, or systems in which hacks have been done by clueless sparks who break common sense or code - Somewhere down the circuit they "borrowed" a Phase from a light switch (that does not have a Neutral in the box) and a Neutral from some other circuit, and your surprise is ready

This and other similar hacks are primary causes of some of the most extreme dangerous situations in electrics which i ever seen. And its not about compliance to code, its about having the most basic common sense to understand that this is in the unacceptable hacks territory



Also, 2 Phases going to a shared Neutral could have been wired in the panel to the same Phase by mistake - Which can result in Neutral current being a plain sum of the Phase currents, instead of a vector sum of them (which limits the current to that of the max of the phase currents at most, not counting harmonics or some very unlikely power factor conditions)

Not so long ago i was looking into a case in a friend's workshop, where a machine with belt (3 phase 400V motor) would buzz and trip the motor protection when plugged into one specific receptacle. Comes out, the entire subpanel in that area was not getting phases R,S,T, it was getting R,S,S !! The single phase loads connected there worked just fine as expected so the problem have not been found until then
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