"LIGHT FALLS FROM CEILING, AIRCRAFT CABLE FAILS" ...coming to a install near you!

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forabit

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"LIGHT FALLS FROM CEILING, AIRCRAFT CABLE FAILS" ...coming to a install near you!

Because I have seen this happen I was wondering if anyone else has seen this or heard of this:
Aircraft cable hung flourecent lost EGC and used the "cable" to (try) trip the breaker. "Cable" does not have the ampacity to handle the load....light falls.

Like I said I have seen this happen and am wondering when they will stop making these death traps?
 
forabit said:
Because I have seen this happen I was wondering if anyone else has seen this or heard of this:
Aircraft cable hung flourecent lost EGC and used the "cable" to (try) trip the breaker. "Cable" does not have the ampacity to handle the load....light falls.

Like I said I have seen this happen and am wondering when they will stop making these death traps?
Click to expand...

It seems like a darn remote possibility.
 
forabit said:
Because I have seen this happen I was wondering if anyone else has seen this or heard of this:
Aircraft cable hung flourecent lost EGC and used the "cable" to (try) trip the breaker. "Cable" does not have the ampacity to handle the load....light falls.

Like I said I have seen this happen and am wondering when they will stop making these death traps?
Click to expand...

How does a fixture lose an EGC?

And you say you have seen aircraft cable get so hot it melts (3000 F or so) and fuses open without tripping an OCPD?

And who are 'they'? The ones you say are making death traps?
 
forabit said:
Because I have seen this happen I was wondering if anyone else has seen this or heard of this:
Aircraft cable hung flourecent lost EGC and used the "cable" to (try) trip the breaker. "Cable" does not have the ampacity to handle the load....light falls.

Like I said I have seen this happen and am wondering when they will stop making these death traps?
Click to expand...

I would bet the aircraft cable has adequate ampacity to trip the OCPD. But it is not supposed to be used for that purpose. How is this any different than a light fixture hung with a chain?
 
forabit said:
Because I have seen this happen I was wondering if anyone else has seen this or heard of this:
Aircraft cable hung flourecent lost EGC and used the "cable" to (try) trip the breaker. "Cable" does not have the ampacity to handle the load....light falls.

Like I said I have seen this happen and am wondering when they will stop making these death traps?
Click to expand...

Anecdotal evidence does not provide enough proof to support your claim "death trap".

Surviving a crash in a car rated poorly does not mean much. Someone you know getting hurt badly in a particular model of a car have no greater weight than reading about someone getting hurt badly in that model car.

You need to consider the probability, likelihood of reoccurrence and cost of incident vs prevention.

Slip and fall injuries are fairly common. You could slip on ice or gravel and smash your head on a fire hydrant.

A.) Accept the risk and continue to walk as you've always have.
B.) quit walking outside.
C.) wear a helmet when walking just in case.

Option C offers protection from relatively small risk at a low financial cost. You're still not protected form a car losing control and running you over or getting attacked by a mugger.
 
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Electric-Light said:
Slip and fall injuries are fairly common. You could slip on ice or gravel and smash your head on a fire hydrant.
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My father got out of his car at an automatic carwash, it was icy, he slipped and fell and was pierced up through the armpit with one of those orange traffic cone thingies.

I guess we could ban those orange traffic cone thingies. Or maybe ice.
 
K8MHZ said:
How does a fixture lose an EGC?

And you say you have seen aircraft cable get so hot it melts (3000 F or so) and fuses open without tripping an OCPD?

And who are 'they'? The ones you say are making death traps?
Click to expand...

EGC's are internal and they are not involved in the functioning of the equipment, a passive component, so one never knows if they are in place or not. Unless you specifically test for it before energizing the serviced equipment, you won't know if it is there effectively, or not. We test for wire continuity and megger resistance on the phase and neutral before putting it in service (not necessarily light fixtures though:D), but nothing is done for the EGC. (Testing voltage difference between the neutral and ground wire is a pretty good indication though.) "Loosing" an EGC to vibration or whatever is not a common, but neither it is an unheard-of occurrence.

I had a 400'+ heat tracing circuit, without GFP, and have burned up about 150' of it with a short between the metallic braiding and the phase wire without the breaker ever betting an eye. The braiding was grounded. (Talk to Rich Hullett @ Thermon.)
 
weressl said:
EGC's are internal and they are not involved in the functioning of the equipment, a passive component, so one never knows if they are in place or not. Unless you specifically test for it before energizing the serviced equipment, you won't know if it is there effectively, or not. We test for wire continuity and megger resistance on the phase and neutral before putting it in service (not necessarily light fixtures though:D), but nothing is done for the EGC. (Testing voltage difference between the neutral and ground wire is a pretty good indication though.) "Loosing" an EGC to vibration or whatever is not a common, but neither it is an unheard-of occurrence.

I had a 400'+ heat tracing circuit, without GFP, and have burned up about 150' of it with a short between the metallic braiding and the phase wire without the breaker ever betting an eye. The braiding was grounded. (Talk to Rich Hullett @ Thermon.)
Click to expand...

I guess I don't understand what that has to do with my questions.

:?
 
forabit said:
Because I have seen this happen I was wondering if anyone else has seen this or heard of this:
Click to expand...
Nope, never heard of it and never seen it happen and I have had a number of projects with probably a couple thousand total fixtures installed with aircraft cable. I think it may be more appropriate to address the actual installation and installers before you worry to much about the method.

Roger
 
roger said:
Nope, never heard of it and never seen it happen and I have had a number of projects with probably a couple thousand total fixtures installed with aircraft cable. I think it may be more appropriate to address the actual installation and installers before you worry to much about the method.

Roger
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I've never seen it happen either. There is a recall of lights suspended by wire for failing, but it is not aircraft cable, it's just fixture support wire, and I'm pretty sure it has nothing to do with losing an EGC.
 
K8MHZ said:
I guess I don't understand what that has to do with my questions.

:?
Click to expand...

I directly answered your first two questions. Perhaps I should have emphasised that the Thermon, self regulating heat tracing cable employs a stainless steel braid. The detailed construction of such cable can be found on the Thermon site. The arcing ground sustained failure, before GFP requirements, were a common failure mode. As the braid installed over the first layer of insulation then have an extruded Tefzel overjacket, some of the braid strands would break. Upon heat cycling these loose strands would puncture/penetrate toward the bus wire and eventually produce a high resistance fault that was sufficient to melt both wires, but not sufficient to trip the circuit without GFP.
 
I would agree that this is an unlikely accident, but it could happen.
Stainless steel wire (often called aircraft cable, even if not actualy used in or approved for use in aircraft) has a relatively high resistance when compared to copper.
A relatively small current, perhaps a few dozen amps would make it hot enough to fail.
The small thermal mass of the aircraft cable could result in it getting dangerously hot before a 20 amp breaker trips.

The answer would appear to be better workmanship on site, and better qaulity control in the factory to ensure that the EGC remains reliable for the life of the installation.

In high risk situations it might be worth duplicating the EGC, or use of a GFCI.
 
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