Shock From Speaker Connections. (1 Viewer)

[BAF]

While helping a friend hook up his receiver, I was shocked (electrically) for reasons I cannot understand. This is a new setup. He had speaker wires installed to various rooms during his remodel;they terminate in banana plug receptacles behind his receiver, but are unlabeled. In trying to ascertain which plugs were connected to which speakers, I touched a D battery across the red and black receptacles for individual speakers, and was in large measure successful in hearing the appropriate sound from various speakers.

It was when touching across a set of wires that were probably not connected to speakers when I was shocked. The patch cords I was using had brass connectors which I held. When I was holding the connectors, no problem. When I held the connectors, and touched the two ends of the D cell, I was shocked with what was probably about 110 volt, low current. Measuring across the receptacle contacts showed no voltage. I tried it again with the same shocking results. I don't understand how this is possible. Of note is that connecting here may have previously blown his amp! Any suggestions?

 

[JohnRice]

Ya think?

You are certain there is no voltage from the wires? Did you check both DC and AC? My guess is it is AC. I have no idea what the wires are for, but you need to find where they are connected or at the very least cap them off with a warning.

 

[BAF]

Checked AC--nothing. Did not feel like DC so didn't check. Agree should be capped off. Should probably check between both sides and ground. The mechanism of the shock in these circumstances still eludes me. Thanks for you thoughts.

 

[Allan Jayne]

Audio is AC. If the amp is turned on and playing, and you try to measure DC voltage, you may measure zero volts and the speaker wires can deliver a shock you can feel.

Some digital voltmeters will measure minute voltages that older analog (needle) meters do not measure. So the lines you were measuring across might not be truly dead.

Some household current electric wires may be totally disconnected but may carry minute induced voltage from other live wires they are juxtaposed with let alone twisted together with, and you might feel a shock when you touch the "dead" wires.

It is acceptable and proper (power pole linemen do it too) to short a wire that is supposed to be dead to ground while working on it. Be sure to remove the extra alligator clip shorting wire when you are done working.

Video hints: Video Technicalia Made Easy

 

[chuckg]

It is possible for a piece of wire with no connection at all to carry enough voltage to give you a tingle. Any wire acts as an antenna, and there is a pretty steep voltage potential between the ground and the second story of your house - just a natural fact of the Earth.

You can light a neon bulb with 100 feet of long wire 20' above ground connected to one end of the neon, and the other end of the neon grounded.

It is also possible that someone scraped a wire, and you've got a small short. It is doubtful that a wire would pick up much voltage or current from adjacent wiring in the house....some tiny bit, yeah, but not enough to feel.