Originally Posted by RJHuser
Lets clarify one thing. Yes, if I were working on a heavy cable connected to the battery, I would disconnect the negative cable from the battery. That cable has the ability to cause damage - to the battery - with the possibility of secondary damage to me, electrical or chemical burns.
However, the OP was discussing a very small size conductor (on the meter) to a FUSED small sized conductor in the trailer. Being IN the trailer, it is highly unlikely to find a grounded piece of metal for a accidental short to occur - we all have had problems with grounding in trailers. If a short to neutral did occur, the worse that would happen is the fuse would blow.
I will restate what I said - 12 VDC won't hurt you. The analogy used for electricity is water flowing in a pipe. Voltage is analogous to pressure and amperage is analogous to volume. If the water pressure (voltage) is low, no mater what the volume (amperage) is, the water flow can be stopped easily, for example, the water flow in a garden hose connected to a low pressure source (say 10 psig) can be easily stopped with kinking the hose or putting your thumb over the end of the hose. Increase the pressure to 10,000 psig, and it not so easy. In fact, a micro volume of flow can cut right through skin, bone, even metal!
As stated by others, until you get above 30 or 40 volts, you can't even feel it if you grasp a conductor in both hands. There is not enough "pressure" to overcome the electrical resistance of the body.
With everything said, I will and do make a conductor "dead" before working on it.
And by the way, in my job I work on electric systems upto 2300 volts with ampacity of thousands of amps, and have been involved with electrical system abov 14k volts.
(By the way, the so called "electric chair" that was used to execute death row prisoners generally used 2300 VAC, anything less and it didn't kill the person or actually ended up "cooking" the prisoner to death. Even at that voltage, there are many accounts of failure to kill the prisoner, or prolonged time to do the deed. Generally, the used three short "shots" to do the deed as it was more effective than one long shot.)
(Still alive and kicking after working on my trailer 12 volt electrical system)
PS: I was successful in my post, to get people thinking and to dispel many of the myths and incorrect ideas concerning low voltage electrical systems.