View Full Version : Electric shock
August 13th, 2008, 23:29 PDT
can you get electric shocks off PV systems. I am trying to understand the mechanics and was wondering at what point in a scale do these panels pose a threat to giving a deadly shock, if you were to handle them in a way that you came in contact with the wiring. My experience is that a car battery does not give a shock, however I imagine putting batteries in series would eventually lead to a hazard, like wise PV panels.
August 14th, 2008, 6:24 PDT
actually, it isn't the voltage that kills you, but the current and only about 35ma is needed to pass through the heart to do it if memory serves. a battery can most certainly provide that current. the voltage comes into play in overcoming resistive losses making that current much more likely to occur. the nec draws a line of about 50v, but one can accidentally touch say 120vac and be fine and the next incident hit 48vdc just right and suffer a shock that could induce death. respect it all.
August 14th, 2008, 6:40 PDT
Ditto, The human skin, on average, (clean, dry) is high enough resistance, that 12 & 24 are nearly completely safe, and as you get higher voltages, a little more current flows. NEC draws the line at 50V, beyond that, it's a fairly sure thing you can "feel" it. 10mA [.01A] thru the heart muscle, is all it takes to screw it up.
August 14th, 2008, 16:15 PDT
Years ago when I was working as a small engine mechanic, I got my metal watchband across battery on a riding mower. It burnt a hole in my wrist under the watch, watch didn't work any more either. I've never worn a metal watch band since unless I'm getting dressed up (and hopfully not working around batteries). Someone else had to pull the watch off. Didn't shock me, but burnt me.
August 14th, 2008, 17:18 PDT
12v unless u lick the poles at the same time nothing, pretty much the same at 24v but you start to get a tingle at 48 volt. Plus please remember a 48v nominal array in VOC is more close to 70v and u will get a more than a tingle at this level. I got a belt from a nominal series array at 72v voc 104 v and u are well aware of it. Its differnet from Ac where you get a muscle wobble at 50 or 60 Hz more of a constant buzz thats not comfortable.
I guess the experts will frown at my observations but as I advise higher nominal system voltages DC Im learning to respect the power these systems can pass through the carbon life form. IE Me :blush:
But Im not the first or last to not respect PV power as low volume output or input, would I grab my live terminals from my 2.4kw array on a cool sunny day at 24v not on your Nellie.
August 14th, 2008, 17:53 PDT
Why is it that motorcycle batteries have such a great affinity for metal. A co-worker somehow got his wedding ring welded to his motorcycle battery, and it literally cooked his finger off. No saving that digit.
So why do they say to tape up wrenches and such when working around batteries ...
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