ECN Forum Forums Safety Discussion and News Safety News and Product Recalls Burning Wirenut

HotOne,
some of what you ask is detailed in the substaintiations forwarded to CMP2

~S~

~S~:
OK, Thanks, I'll do some reading there ASAP!

Ok, Apart from my tests, I also saw a site with an NEC proposal, I think it was combinaisonAFCI.com, (try) where the author seems to be qualified.
Have a good day.
Regards,
FLV

HotOne,

first off incendiary levels can be reached without an arc

secondly, the series 'bad connection' has always, and will most likely always be the most prevelant culprit

i mention this because we (American electrical community) have nothing to address this

~S~

~s~:
Yes, you can be incendiary ie: Renos toaster and Tom Edisons light bulbs, but those are designed to do that.

Unless we all get zapped into the fourth dimension, and enter the 'perfect world/utopia' the bad connections will be around.

Yes, there is no device available that we could use to prevent this issue, and I'm now questioning IF the combo AFCI will do what is claimed. I wonder if anyone here has attempted to do a series arc test on an AFCI CB? (Greg)
(Reno)

Hello HotLine1 and sorry, it's was no clear: "Ok, Apart from my tests, I also saw a site with an NEC proposal, I think it was combinaisonAFCI.com, (try ON GOOGLE) where the author seems to be qualified. "
I apologies.
Regards,
FLV

Alas, I have never been in a position to do any truly proper testing.

Mike Holt had a gizmo that mounted electrodes on a rail, and he could slowly separate them to make a controlled arc. I have not seen him use this since he visited AFCI central and 'drank the kool-ade.' IMO, his device would provide a very good demonstration of any type of AFCi.

Loose connections? I think we're on a unicorn hunt here.

Several years back, I posted an Image of an Ideal Red Wirenut, which had extensive Heat-Related damage.
The Wirenut was found in a 4s Box, during the Demo Phase of a Tenant Improvement (T.I.) Project.
Several others were found as well; a few were so Heat Damaged, that they disintegrated upon touch.

The culprit: Poor Workmanship!!!

It was obvious that the Terminations were done by more than One Person... most likely there were Three People doing the Makeup on these Ceiling Boxes.
The Boxes with "Poor Workmanship" comprised of less than 20%, had no Writing on the Covers (to indicate Panel / Circuits + Voltage), were only the Lighting Circuits (277V), and were the only Terminations where no Pre-Twisting was performed.

The Pre-Twisting inclusion is simply an observation of bulk Terminations, not an indication of Termination Failure where not performed, as I have seen many undamaged non Pre-Twisted Terminations.

Points to ponder:

1: The Service Capacity which these Lighting Circuits were fed from, was 4,000 Amps - 480Y/277V 3 Phase 4 Wire; so the Service Disconnect (Main Circuit Breaker in this case) included GFPE (Ground Fault Protection for Equipment).

2: The settings were dialed in for most restrictive / highest sensitivity.

3: Although the GFPE does not directly scan for Series Arcs, there was evidence in some of the effected 4s Boxes, showing L-G Arcing.

To me, the Termination issues discovered on this Project are very rare scenarios. I had been in the field for at least 24 Years when discovering the Bad Terminations. Prior to this I had uncovered only a few (no more than 5) such situations - only there was a single Termination issue (only One Wirenut in One Box total), and the Wirenut was either an obviously over-used Ideal, Scotchlock, or something in the "El-Cheapo" line...

My Conclusions:

a: Termination Failure is directly related to the experience of the Person performing the task,

b: The Workmanship placed on any installation, may vary with a Person - per the situation involved (i.e.: bad day = poor makeup),

c: The Wirenuts in this case were damaged from excessive Heat, caused by drawing 100% LCL Current through the internal spring mechanism of the Wirenut,

d: Little, if any, Series Arcing was experienced in the Wirenut,

e: The only way any Protective Device would react to these scenarios, is when a Bolted Ground Fault occurred (Wirenut Spring made contact with the Metallic Enclosure of an Outlet / Junction Box),

f: This is not a Brand-Specific issue. All brands and types of Solderless Terminations have the potential to fail this way, due to Poor Workmanship.

Just my 2¢

-- Scott

Scott, please allow me a rebuttal here.

a bad connection is the most common malady of the electrical trade,

said bad connections are usually seen as overheated terminations

this can be described as a series event, or a 'glowing contact'

give me free rein in any house wired a generation ago, and i'll wager i'll find you multiple examples

further, a glowing contact can produce incendary levels before an arc occurs

UL has finally come around recently to recognize said glowing contact as a major fire safety consideration

please look at the latest IEEE paper via a Mr Joe Engle, phd, for this>>>

http://www.combinationafci.com/resources/doc_ieee_combination_afci.pdf

thank you


~S~

To the comments made by Scott, I would like to add one thing. He mentions lighting circuits, 277 volt, etc.

Could the circuit(s) been operating at or near max amperage?

Yes, I agree with the 'workmanship' statement, as I said back in this thread. No I would not expect a GFPE main to see this potential issue until it was a L-G fault, which may be after the situation evolves into a fire condition.

And, to Sparkys comments, yes, I have found some old, porcelain wire nut, twisted, & friction taped cloth wrapped RH that had issues, most of which reared their heads when oversized plug fuses were installed. Some burned clear, a few resulted in structure damage. (From my young days in Newark, NJ areas)

'Newer' work bad connections of wire nuts (Yellow & Red) with scorch marks I have also come accross, not 'lots', but more than a handful for sure.

No debate that these situations can be a cause of a fire, Hence, splice boxes require covers.