QO failures

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junkhound

Senior Member
Location
Renton, WA
Occupation
EE, power electronics specialty
'Kate Megahertz' mentioned on another thread that QO breakers have seen some bus contact failures.
The photo is from a Schneider web page, but they give no other details.

Anyone have a link or personal experience about how prevalent this is ?

Did Sq D switch to aluminum busses recently or sometime in the past that would initiate problems ?

qo.jpg
 

K8MHZ

Senior Member
Location
Michigan. It's a beautiful peninsula, I've looked
Occupation
Electrician
'Kate Megahertz' mentioned on another thread that QO breakers have seen some bus contact failures.
The photo is from a Schneider web page, but they give no other details.

Anyone have a link or personal experience about how prevalent this is ?

Did Sq D switch to aluminum busses recently or sometime in the past that would initiate problems ?

View attachment 14163

First, K8MHZ is my amateur radio call sign, so K8 isn't Kate. I wanted W8MHZ, but it was already taken. 8 is the district that Michigan is in. There are 10 districts.

Second, do you have a link for the picture?

Beside my personal experience, an EC I know that has been installing QO panels has told me he has seen this recently as well. Neither one of us has seen a Homeline panel do this.
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
It looks like the breaker was installed with its bus connection on one side of the bus finger instead of straddling it. Those clips can be damaged by incorrect handling and installation and if they are you will have exactly what you see here...high heat damage at the point of connection. This happens with all brands of breakers.
 

Jraef

Moderator, OTD
Staff member
Location
San Francisco Bay Area, CA, USA
Occupation
Electrical Engineer
Without knowing the context, you can't draw conclusions from the photo alone. For example, Sq D has been hit hard by Chinese counterfeiters lately, this photo may have come from a presentation on what can happen. Or as mentioned, it may have been a warning about making sure the breaker is stabbed on correctly. We just don't know, so we should avoid creating a false panic here.
 

junkhound

Senior Member
Location
Renton, WA
Occupation
EE, power electronics specialty
Here is the Schneider link:
http://ecatalog.squared.com/pubs/Electrical Distribution/Load Centers/0106BR0502.pdf

Also found this after initial post:
http://inspectapedia.com/electric/Classified_Breaker_Warning.php

a sentence from page 2 of the first link also implies counterfeit or non-compatible non-QO breakers or othe mfg panels with; Aluminum bus bars ? : ...Breaker is installed in another manufacturers load center..





Sorry about the 'Kate', was just having fun with you, which is why I put it in quotes. My old boss (pioneering ham, a nonagenarian nowadays) still has his initials as call sign and auto license plate also, K7HO. My cousin was W9EBX in IL, sometimes called him 'whiner'.

PS: want to know how dumb I am ? Had to have it explained to me 65 years ago why dah-dit-dah-dit dah-dah-dit-dah was replaced by SOS. Seek you was to generalized apparently to attack attention. Somehow did not equate CQ with 'seek you' ; kids nowadays with texting come up with the wierdest combinations.
 
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