Tuesday, December 15, 2009

As Far As I Got...

This was as far as got this afternoon at the shelter where I volunteer. When you find a junction box that is NOT water tight, has melted wire nuts, was previously secured to a spongy roof with a thin bead of silicon caulk, that is driving 2 green strings of 180 lights at 45 watts each... you just Back Away, slowly, as a registered PE.

The duct-taped splices, the lack of water-tightness, the black-melted wire nuts that used to be red (joining two 12 ga neutral lines to the photo sensors seen here, in one big molten ball of copper), the melted foam rubber seal on the cover... crispy!

I did not supervise the reassembly, nor did I assist with my manual labor. I did advise what needed to be done to correct the NFPA 70 NEC (National Electric Code) violations. It's a good thing it doesn't rain often in Arizona. Yikes.

Double Checking my own math
45 Watts x 180 lights = 8100 Watts
P = I * V (Power = Amps X Volts)

8100 Watts / 120 VAC = 67.5 Amps.
(in my head, I came up with "about 65 Amps", as I figured in the parking lot without paper or pencil... it's nice to know I can still do math even at my advanced age.. =P )

A 12 AWG wire, at 30 Deg C, can safely carry 23.1 Amps... 1/3 of what each of the two the 180 light strings are calling for. Again, Yikes. It's been installed for 20 years... I recused myself. The main maintenance guy I work with there said he'll work to get it correct over the next week...


  1. yikes!

    just recently, we had a grounding issue (as in, THE ground) fixed at the house. i didn't know the previous setup was hazardous.

    i don't know much about electricity, but i'm still excited by the orange outlets i've got my computer plugged into.

  2. I quite liked electrical work when I did some in our house in Chicago. I still have the armored cable cutters and other tools in Alabama. Part time electricianing seems like something I might consider if I ever retire.


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