Stupid Reasons to Blow Circuit Breakers

[DerbyDad03]

A Humbling Post here:

I go years without popping a breaker and then I pop 2 different ones in one day - both of which were my own fault.

1 - Cleaning the garage the day after Thanksgiving. It's a bit cool out, so I plug in the electric heater. There's also a freezer in the garage and 3 light fixtures. Everything is fine all day and I'm nice and toasty. Then 5 PM hits, the timer for the Christmas lights turns on and suddenly I'm standing in the dark. Oh well, almost done, I'll live without the heater.

2 - I need another shelf in the garage so I grab a piece of scrap and head down to the shop. I keep the table saw on a rolling base, pulling it away from the wall when I need to use it. I pull it out, make 1 cut and start another one when I see sparks by the motor and the saw stops. Damn! Did I blow the motor?

Nah. In my haste, I hooked the power cord for the drill press with the table saw's belt cover when I rolled it out. Everything is black on that part of the saw and there's a black cord from the switch to the motor in that area, so I just didn't see the extra cord - it all just blended in.

I was fine for one cut, but halfway through second cut the belt wore through the drill press power cord and shorted it out, blowing the breaker.

Learnings: Haste makes waste, at least 2 of my breakers work fine, the garage needs another circuit.

[jeff_wisnia]

I'd hate to tell you how many times in the last twenty years I've nicked or cut through the (orange) extension cord I need to use when trimming the shrubs around our house with and electric hedge trimmer.

Thank G_d for GFI breakers.

You were correct, Haste makes waste (and babies too).

Jeff

[Percival P. Cassidy]

*I* have not done it, but another member of the family has (more than once), so we now have a cordless hedge trimmer.

Perce

[Roy]

=3D=3D Ask Santa to send you an extra elf assistant to watch over you and protect you from yourself. In any case remember the emergency number

911 and keep a phone handy in the garage...a first-aid kit as well.

=3D=3D

[hallerb]

A exciting day:(

I was rototilling and it hit a big rock:( bucked and hit the main entrance cable, shower of sparks.

I nearly died that day. for real. my neighbor had just put the rubber hand grips back on the tiller. without them standing in wet mud i would of been electrocuted for sure

[mkirsch1]

Uh-huh... The electricity would've skipped over a steel path straight to ground (i.e. tiller tines) to go through your high-resistance carcass?

[clare]

Quite possibly not - the circuit through the tines of the tiller to ground was much lower resistance than through your body. You MAY have been electrocuted 0 more likely you would have gotten a pretty serious shock - and quite possibly not even a "tickle"

[Edward Reid]

Ground itself has significant resistance -- that's why grounding rods require a lot of ground contact, a great deal more than the tiller blade. And it's not certain that the tiller blade would even have good ground contact. And unless the grounding is adequate to reduce the voltage potential, it does not affect the shock given. Since the poster hit an entrance cable, the breaker was at the transformer and was probably several hundred amps at least.

1 mA is enough to feel, and 100mA is enough to kill.

Human body resistance may vary from 1000 ohms (wet hands) to 100,000 ohms. (Numbers from a Wikipedia article, so take it for what you think it's worth.) Assuming a 100V shock (one leg), at the highest resistance the shock would be felt, and at the lowest resistance, electrocution is a distinct possibility.

Edward

[hallerb]

thats a interesting thought i never even considered.....

well one day for sure i will lose..... but it wasnt that day:)

[Roy]

=3D=3D Through my lifetime I have had about six or so substantial tickles that I have encountered. How many tickles are allowed before the big zapper gets you? =3D=3D

[Tony Miklos]

I hope we are allowed a hell of a lot of tickles. I've had thousands of tickles, and a hundred or so pretty damn bad shocks that left easily seen burnt marks on my fingers. Mostly small burns, but burns indeed.

[DerbyDad03]

What constitutes a "tickle"?

I got hooked to a 300VDC power supply while taking an electronics course in the Coast Guard.

It was stuck between my hands and I lifted the 20 lb device off of the workbench like it was weightless.

The current went in one hand, across my chest and out the other. I have burn scars on both hands where they were in contact with the chassis.

A classmate tried to pull the plug by grabbing the cord, but the power strip came off the workbench with it. Another classmate reached over and slammed the power strip back down onto the workbench, finally killing the power.

I spent the night in the hospital and when I returned to class the next day 2 things had changed:

1 - All of the power strips were screwed to the workbenches. 2 - 3 guys quit the class and decided not to become Electronics Technicians.

Meanwhile, I went on to become a LORAN Transmitter Technician, working on equipment that had power supplies that produced 25K VDC.

[hallerb]

most schools have kill switches thruout room that kill all workbenches when pushed, a big red button

[Roy]

=3D=3D Yoiks, my tickles were never as bad as that...I didn't have any burns. =3D=3D

[hallerb]

DC tends to burn much worse than AC..

I repair office machines for a living and have gotten zapped many times.

One time I found a manufacturers defect:( I turned a key lock switch and ended up across the room looking up from the floor.....

[The Daring Dufas]

In my experience, high frequency AC hurts worse than any other shock I've had. The horizontal output of old tube type TV sets can make you feel like you've been turned inside out. It goes to the bone. :-)

TDD

[David Nebenzahl]

On 12/4/2010 9:18 AM Roy spake thus:

Dunno. My last "tickle" was actually the worst jolt I've ever gotten, one I won't soon forget.

Was working on a friend's shop in a commercial space in San Francisco, installing lights. Somehow contacted two wires that I *thought* were disconnected but weren't. What I didn't know at the time was that these weren't 120 volts, but instead were 277 volts.

Big difference. Big buzz. I was on a stepladder at the time, and am

*very* lucky I wasn't thrown clear off.

[DerbyDad03]

Schools may have emergency power switches now, but this was in 1975 in a school housed in converted horse stables/army barracks on USCG Base Governor's Island, NYC.

This image shows the building that housed the Coast Guard schools, barracks and offices back then. Note the arched brickwork in the lower right. There are many more of these converted entrances all along the front of the building behind the trees.

Those used to be the entrances to the horse stables when the Army used the island in the 1800 and 1900's. The horses lived on the first floor, the soldiers above. The smell must have been interesting.

We used to have to walk the entire length of the spooky, dimly lit attic, punching a Detex clock, as part of our security and fire-watch rounds. Not my favorite activity at two in morning.

Here's a view of the center structure. Each of the arched windows was a former entrance to a stable that has since been converted to an office or classroom..

[DerbyDad03]

While working on the LORAN transmitters I mentioned above, I witnessed a guy come as close to death from electrocution as you can get.

When you removed any of the 3' x 3' panels from the side of the transmitter, a spring loaded interlock grounded all high voltage. If you then removed any of the grounded bus bars from the big oil filled caps, you were required to attach a grounding strap across the terminals to prevent the caps from charging back up from the energy in the room. (There was always 1 live transmitter in operation while we worked on the standby)

A tech had moved a cap to the workbench, shorted it out, and then later put it back into the transmitter. He removed the grounding strap, then got distracted and didn't hook up the bus bars. After the cap had been sitting open for a few hours, he stuck his upper body into the transmitter and reached across the cap. His chest came in contact with the 2 terminals and it threw him upward into the bottom of the shelf above, which bounced him back down onto the cap, which - not having been fully discharged yet - threw him back up into the upper shelf one more time.

This time he came down on the cap and sort of slithered to the floor, almost unconscious and very bruised and battered.

We were 60 miles above Nome, AK, so we had to call in an air-taxi from a nearby village ("nearby" was 15 miles across the Port Clarence Bay) to come get him and take him to the hospital in Nome.

[The Daring Dufas]

I heard of a bald electrician who was working on 277volt lighting when he raised up while making a connection and his bald head touched the fixture. R.I.P. A lot of guys are hurt or killed working on 277volt lighting circuits because they're not careful enough.

TDD