Burnt time clock conductors

[nizak]

Got a call to a business that had non working exterior lighting. Opened the time clock and found insulation on load conductors burnt back about 2 inches from terminal.Time clock mechanism was melted at terminal where wires were landed.
I disconnected wires, rung out each conductor and found nothing grounded. I energized them and had an acceptacle amp draw for the # and type of fixtures that were being operated.Building owner states that C/B never tripped, he turned it off after seeing and smelling the burnt conductors. Out of the 8 fixtures on the exterior, I found one that needed a ballast replaced(150W HPS).Owner told me that fixture had been out for awhile prior to this problem. Time clock failure??? Loose terminal???, don't really know what to attribute it too. Any thoughts?

 

[mgookin]

What's the make & model on the time clock?

 

[GoldDigger]

Could have been failing switch contacts overheating the wires.
Could have been loose screw connections overheating the wires.
But if it was both (or more) load circuits on separate switch contacts it is harder to see how one bad screw or contact could start the whole thing.
My first concern would be whether the contacts were rated for the actual load.
I suppose one failed ballast could increase the current on the circuit enough to damage the wires if the wires were too small relative to the C/B.
Lots more info needed.

Tapatalk!

 

[ptonsparky]

Over torqued. Under torqued. Overloaded. Age.

 

[nizak]

T101 Intermatic. 40 amp rating/125v. Time clock is approx 10 years old. Total load 17 amps connected. Supplied by QO 120 breaker.

 

[pjholguin]

From what you describe, this is a typical signature of a loose or improper connection. If you had used an IR camera, you would see the heat signature starting at the terminal( hottest point) and as it travels away from connection the heat signature dissipates. Seen it several times before and after a insulation failure.

T101 Intermatic. 40 amp rating/125v. Time clock is approx 10 years old. Total load 17 amps connected. Supplied by QO 120 breaker.

 

[masterinbama]

Clock contacts deteriorated over time. Resistance creates heat and heat creates resistance until.........................................

 

[K8MHZ]

From what you describe, this is a typical signature of a loose or improper connection. If you had used an IR camera, you would see the heat signature starting at the terminal( hottest point) and as it travels away from connection the heat signature dissipates. Seen it several times before and after a insulation failure.

I am going to have to agree. The T101s are pretty stout, but it can be an SOB to get #12's in and tightened properly.