Electrical wiring in the home shop.

[LIALLEGHENY]

Speaking of a concrete floor in a shop.....had a friend years ago , whose brother died from electrocution on a wet concrete garage floor. He was hosing out the floor in his garage and put his hand on his air compressor....and that was it. An investigation revealed the compressor had been wired up improperly many years prior, an issue with grounding and a hot lead . The water enabled the resistance of his rubber boot soles to be overcome creating a path to ground through his body.

[SteveHGraham]

I have had two GFCI outlets die and cause problems during the last two years. They are not reliable.

You can buy an outlet with an alarm on it, to tell you the food in your garage freezer is starting to thaw. Just pray you're not on vacation when it goes off.

[liveaboard]

I've had whole house GFI breakers in my breaker boxes for 30 years; I think 1 failed during that time.

[Mr Ron]

Before the use of polarized plugs became standard on all electrical devices, the return leg of the device could be wired to the return leg of the power source. Reversing the plug in a receptacle, would make the entire device hot. Touching that device could be ok as long as you were not a path to ground, but if you were, electrocution could be the result. Being AC, the device would work either way, but if the device was positive, touching it could give you a shock. Sometimes when you lightly touch a device, like a lamp, you will feel a tingle sensation. That tells you there is a voltage leak and that lamp should be disconnected. Same can happen with power tools. Insulation can break down causing voltage leak. You should have the device rewired or toss it; nothing to mess around with.

[NP317]

My concrete floors are well sealed. I wonder if that changes the ground resistance?
RN

[reubenT]

only if it's a non conductive coating of some kind of plastic compound like polyurethane. My wiring is atrocious, but it's a crude dirt floor shop and the dirt is pretty dry. Didn't want concrete in the foundry area anyway, and couldn't afford concrete when I built it. Only spent about $200 to build a 30x60 shop. Pole barn with locust poles and sawmill lumber. The only cost was metal roof, short cutoffs from the metal roofing place, and a 50 lb box of nails. The electric wiring on our whole place is pretty bad. No improvement since about 1964 when it was first installed in the old house. The house was built likely over 100 years ago, they didn't even have mortar for the chimney and laid up the rock with clay. I plan to get it all reworked but that job keeps getting delayed.

[John Hasler]

Mr Ron writes:
Before the use of polarized plugs became standard on all electrical devices,
the return leg of the device could be wired to the return leg of the power source.
Reversing the plug in a receptacle, would make the entire device hot.

I don't believe that it ever has been permissable to sell a device wired that way.
Exposed metal parts were always isolated from the wiring in device with unpolarized plugs.

[Patio]

The way I understand the world, is that heat in most systems, are caused from losses in the system, unless creating heat is the intended outcome. Heat in an electrical system, unless desired, is due to bad connections for the most part. It is most often noted by a dis-colorization of the surrounding metals. They usually turn grey. If you have an outlet that the plug does not fit into snugly, change it out. It is only a matter of time before it fails or worse.

Long before I became an electrician, I had a job that required a lot of travel, so I had a travel trailer. One nice sunny day, while hanging out, with just socks on my feet, I notice a friend walking by, so I grab onto the door jam with my left hand and lean out to say hi. I had leaned out to far enough that my right foot planted itself on the ground. At that moment i became hung in place, unable to release my grip on the trailer, because of an electrical voltage present on the skin of my trailer that was now coursing through my body. I was frozen in place, mouth opened, unable to speak, and unable to move. I watched my friend walk past without him ever noticing my predicament. I knew I was dying in place. It was a surreal moment. I was able to force myself to slowly lean further out, until the weight of my body forced my hand loose from the body of the trailer, and I fell to the ground. I later learned what had caused the problem. One of the other trailers on the same circuit as I, had reversed neutral and hot wires, causing the skin of my trailer to be hot. We rewired their plug on the their cord and things were good again. Another time this happened, I came home to find my dog sitting on the step to the trailer, shaking like as if he were cold, yet is was a summer day. He was tied to the trailer by a metal chain and a steel cable that ran the length of the trailer, as a runner. It only took me a second to figure out what was going on. I felt very bad for my dog that day, as I knew what he was going through. I personally believe that 110V can be much more dangerous than 220V systems, for the reason that if you get hit with 220V, it will kick you hard enough you may not get hung, where as 110V will just hold you. I have heard it said, that if you are going to touch something to see if it is hot, use the the back of your hand. Personally I don't think it is a good method at all, and meters or other devises should be used to test to see if there is voltage present.
For those that don't understand the basic principle of electricity, I like to explain it like this. Electricity, water and most other fluids work under the same principles and for this we will use water because it is what most people know. In water, Pounds per square inch (psi) is a unit of measure for how much pressure is in the system. In electricity Voltage is a unit of measure (V or E, E is Electromotive Force), for how much pressure is in the system.
Gallons per minute is how much water passes a particular point in a measure of time. In electricity Amps is a unit if measure for how many electrons pass a particular point in an amount of time. The main limiting factor of a water system is the size of the pipe. The limiting factor in an electrical system is the size of the wire. Try to push to much water through a water system and the pipe will break. Try to push to much electricity though and electrical system the wire will melt. In water the psi times the gpm will determine that amount of work the water can do (I have no idea what unit of measure that would be). In an electrical system the amperage times the voltage will determine how much work the electrical system can do and is measured in watts.
These are principles, that if understood, may apply to many other aspects of life.
I hope that helps someone.

[curtis cutter]

Pat, your story of the trailer incident reminds me of years ago we used 2' by 2' by 4" thick wooden blocks under the outriggers when setting up our fire department ladder truck. It was a common thing to do to distribute the weight over a larger surface area than the 12" y 16" pads that the truck came with.

When we transitioned away from wooden ladders and went to telescoping aluminum booms with aluminum baskets we continued to put the wooden blocks under the outriggers. I am glad it was caught before a possible incident similar to what you experienced happened to a crew member when reaching out to grab a hand railing while the (insulated from the ground by wooden blocks) ladder came in contact with a power line.

After that the 2' by 2' pads were made of aluminum...

[rrnut-2]

I guy that I worked with did the same thing with their dog, only the dog was jumping up and down while they were in the RV playing cards and wondering "what is wrong with that dog"! He found out the moment he grabbed the chain. And the dog sleeped for for two days.

Jim B

[liveaboard]

A GFI can be fitted to trailers, RVs, + boats.
All my boats have them. My trailer too.
The only reason not to do it is if you think the possibility of loss of life isn't worth the money and bother.
With boats, wiring errors of your neighbors can cause your metal hull to dissolve into the water, swimmers to get fried, all sorts of things. It's a known issue.

I also got 'stuck' to a hot terminal long ago, a 220V one of a 100w light.
Similar to Patio's story, I was paralyzed but managed to find the will power to exert enough effort to save myself. I was barefoot on a waxed masonry floor.
I seemed to be stuck by my finger; I planted my feet in the corner and was leaning against it with my weight, or that was what I thought was happening because if it was so, then the current was physically holding me and I don't think that is possible.
In any case, like Patio I came loose and fell to the floor.
There were 2 holes burned into my forefinger, one larger than the other. The small hole was the other terminal prong, that went to the bulb.
I wonder, if anyone had looked, if it was visibly lit?

Whole system GFI might not be required by code where you live, but I'm sure it's not against code to install them anyway.

[SteveM]

One of the other trailers on the same circuit as I, had reversed neutral and hot wires, causing the skin of my trailer to be hot. We rewired their plug on the their cord and things were good again.

That's really scary to think that someone else's hookup screws up your unit.

For those that don't understand the basic principle of electricity, I like to explain it like this. Electricity, water and most other fluids work under the same principles and for this we will use water because it is what most people know.

For about five years, the teachers at one of the elementary schools had me do a presentation on electricity. The teacher had asked a group of moms if anyone could do it and the wife volunteered me. We had hands-on experiments, a hand-cranked generator that ran a motor, a voltaic pile. It was fun.

I made the same water analogies for the kids. Here's what I wrote:
If you think of electrons as behaving like water, then you can make some analogies.
Water flows through pipes - Electricity flows through wires
Water pushes with pressure measured in pounds per square inch - Electricity pushes with pressure measured in volts
The flow of water is measured in gallons per minute – The flow of electricity is measured in amps,
How much work water does is flow times pressure – Same with electricity; we call it watts (that’s the number on the light bulb).
How much water is gallons – How much electricity is watt-hours (that’s the number on your electric meter)
Water flow is controlled with valves – Electricity is controlled with switches
If a pipe breaks, water falls on the ground – If a wire breaks, electricity can flow to “ground”
A larger pipe can flow more water – A larger wire can flow more electricity

Oh, one of the props I had was a pair of army telephones, like the one the colonel had on his desk in MASH.

I told them that the crank was a generator, turned the crank and the other phone rang.

When I was all done with the presentation, I asked if there were any questions.

A girl raised her hand. I asked her what was her question.

She said: "Why do you need a wire between the two phones?"

Steve