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Home Forums General Discussion AC or DC? Re: AC or DC?

#65744
elnav
Member

Anything done poorly can be unsafe. At least one poster suggest 120V AC is more dangerous (a personal perception) than 12V DC Many people are familiar with 12V DC in their vehicle and we all know familiarity breeds complacency. People will work bare handed on energized 12V circuits. I do as well, but I also have been shocked if my skin is sweaty on a hot summer day. Many years of having to work safely has convinced me to follow procedure all the time. Despite this I have been accidentally shocked from time to time.

Most of the people reading these forum posts are not professional electricians or installers. They do not attend monthly safety meetings and in most cases they have not read a dozen or more text books on the subject.

My comments can in no way completely pass on all that I have learned (sometimes the hard way) in a lifetime.

Yes you are correct that if something is done right it will be safe and last for decades. HOWEVER one second of inattention or a forgetful moment could also mean disaster. I know of one situation where a guy was wiring up a light in his boat with the power still on. His hand slipped and the two wires shorted some six feet from the battery. No fuse and the 14Ga wire over heated causing the insulation to melt and char. This released toxic smoke that overcame him before he could take three steps to reach an open door and fresh air. He died!

I myself have done something similar during a forgetful moment.

Fortunately I am here to tell you about it. Learn from my mistakes.

Don’t bother to tell me how you already know it all from the books and therefore you are better and safer than me. When I worked for a power utility I saw a former lineman every morning who was missing his fingers on one hand and half of his foot. He knew better and he trusted the crew chief who said it was safe to work. No one knows exactly what went wrong but this guy got maimed despite the safety rules. It was a sobering reminder to all of us to be very careful and double check every move we made. At the utility the most scary place my partner and I worked in was the DC battery room.

Evidently some people have not realized that most of the wind turbines and a lot of solar panel systems now operate at voltages above 12V. This tells me they are not necesarily keeping up to date and chances are they do not keep up on safety issues either. I am simply trying to point out what may not be the safest approach.

My only reason for suggesting wiring as if for a 120V AC system is because it is the most common and there is a lot of self help books on how to do it right. If you still feel 12V is your best choice then run 12V in the wiring. If you have followed recommended practices ( code) then it will be safe.

Running extensions under a carpet is definitely poor practice. A couple of years back I attended a job site where an inverter system was supposed to be installed. The floor was a mess of extension cords. Someone stepped on a cord and there was a bang, flash and the lights went out.

Extension cords get warm when carrying current. PVC insulation softens when warm. When you step on it the hot wires push through the insulation and can short out. NFPA forbids running cords under a carpet for this reason. They have seen too many house fires started this way.

Most off-grid residents do not have fire insurance and live too far from a fire department. Go ahead take a chance. Someone always wins the lottery. Many more qualify for the Darwin award nominations.