On 10/16/2015 11:59 PM, Texas Kingsnake wrote:
Howdy folks,

I read all the excellent replies (thanks to all). Here's what I am going to
do. I will put on my long linesman rubber gloves, place a thick rubber mat
on the floor in front of the box and use a large insulated screwdriver to
see if the screw (it's slotted, not hex-keyed) will turn and by how much.

I haven't been able to recreate the arcing since pushing the feed wire
slightly right above the bus clamp. I will, on next trip to the box, look
for discoloration of the wire in the clamp area and burn or sputter marks
near the terminal. I will also try to measure the washing machine's start
up current to see if it's abnormally high (if my clamp meter can register
it - I believe it has a peak lock but am not sure - just got a new HF one to
replace the Wavetek that had a terminal battery leak.)

I appreciate the concern for my life, Philo, and my wife is making sure my
will is in order. I will wear goggles since I know a spasm of some sort
could arc weld my screwdriver to the panel and throw molten metal into my
eyes.

DPB - I'll try to take a close up picture of the wire where it enters the
clamp but no guarantees. The last time I uploaded pictures no one could see
them. I'll at least try to describe what I see now I know what I am looking
for.

I'm upstairs now, but for some reason I thought the feed wire was tinned
copper but it could easily be I was looking at aluminum wire and didn't
realize it. The upgrade to the panel occurred in 1972 according to the
labels, and IIRC that's when aluminum was still thought to be a good idea in
residential wiring. I think you're right in that just pushing on the wire
changed something because I cannot get the arc to occur DESPITE putting two
space heaters running at 15A on the outlets served by the left side of the
panel.

It's really just random chance we were both standing where we were when this
happened - who knows how long it could have continued. I tried to assure my
wife the reason that the circuits are in the metal box was to prevent an
arcing connection from throwing sparks into the room. She's with Philo and
thinks resetting the clocks and VCRs is worth the safety edge of working on
a de-energized circuit. My opinon is "meh, you got to go sometime and
getting eletrocuted is probably better than some ways of dying!!!"

I have a neighbor who is an electrician so I am going to consult with him
tomorrow about what to do. If it's discolored and corroded at the entry to
the clamp, I will consider replacing the entire feed wire from the meter to
the panel since I think that's a relative small piece of what looks to be #6
wire - can't read the markings but am on my way downstairs with a camera
with a macro lens. If all the feed wires are AL, I will consider replacing
all three wires from the panel to the meter with new copper. If it happened
on one wire, it's possible it could happen on the others.

And , if the screw won't turn, I won't be spraying it with
anything flammable while it's live. I feel comfortable trying to tighten
the screw and take photos while it's live, but if it requires closer
inspection, of course I will kill the power to the panel.

Thanks again for all the thoughtful replies. It might be a few days before
you hear back from me if the worst comes to pass - well, if the very worst
comes to pass (I die) you won't hear from me so I will try my best to let
you know if I survive.

The worst shocks I've ever gotten were not from replacing breakers in a live
panel but where I least expected it. I was changing a light bulb in a
flooded basement when it popped in my hand and I was suddenly touching the
naked filament wire. Or when I was working on a space heater that had
stopped heating and thought I had unplugged it from the outlet but I had
actually unplugged my DC variable power supply that was plugged in next to
it. ZAPPPPPPP!

TKS




First off, as mentioned ,the power company will disconnect your power
free, so I'd do that. Since what you are doing will only take a minute,
I'm sure they will stick around and reconnect .


That said I already know you are just going to go ahead and do it...so
good luck to you.

In addition the the shock hazard, it the possibility of shorting
something out if your Allen wrench slips. (Hope you saw my photo)

Finally, if things do look at all burned...even a slight tarnish, the
money you spend to have a qualified electrician fix it will be a
pittance compared to your house burning down.