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Unplugging power cords from amps/ pre amps

This might be a stupid question but when there is a thunderstorm lightning storm I used to unplug my power cords from the outlet but now I can’t do that because of a lot of things in the way to reach my plugs from the outlets. I want to know if it is ok to unplug my amps / pre / cdp from the female end that goes to my equipment and then replugging them back after.  Of course the units are off when unplugging / plugging them back. Ty. 

tattooedtrackman

Showing 4 responses by erik_squires

erik_squires
16,564 posts
 

@noromance

You wrote:

Not sure lightning will be stopped by a 6mm gap in a breaker.

Lets discuss. The breakdown voltage of air is about 30 kV / centimeter. A 6mm gap would take 18 kV.

Here’s where it gets interesting. The normal breakdown voltage for insulated 14 gauge wire is between 600V and 1,000V. Plenty for a home, and totally inadequate for lightning.  Any surge higher than that will burn through the insulation and short to ground. 

The normal surge testing is at 5kV, which is believed to be the maximum voltage a home could receive from the electric grid. The reasoning is that the natural inductance, and low insulation strength (relatively) of the wiring that goes to your home would mean anything more than that would naturally find some other path to ground.

So, for anything that comes in from the mains, 5 kV is the absolute worst case scenario. What about a direct strike? If you have 18kV at your breaker or even power switch you have a hole in your living room. :)

Here's where I'm at.  In the half dozen or so cases where I've lost equipment or been present when equipment was damaged it was not from  a direct strike like that. 

So, yes, pulling your gear is the best way, but 99.9% of your damaging surges won't be that kind of strike.

erik_squires
16,564 posts
 

@zlone

Arcing during a disconnect is bad, but AFAIK, does not cause a voltage surge. It does have the potential for leaving carbon deposits which prevent current flow, or heat up and cause a fire. That’s 100% true. I’ve seen it in a bad outlet wiring (my own fault!).

The arcing is proportional to the current flowing at the time the switch or cable is pulled out, or relay disengages. For this reason it’s important to turn off the gear first.

I’m not sure however that it makes much of a difference which end of the cable you pull out, except perhaps that if you pull out the equipment end you risk the chance of the arc damage being on the IEC connector?

Maybe the EMI/RFI noise during the arc can be amplified through the amp, so having it happen further away minimizes the noise?

erik_squires
16,564 posts
 

I mistyped,  I meant to say:

What wears when done too much is the springs in the female sockets, either on the wall or in the cable.

 

erik_squires
16,564 posts
 

Yes, either is fine.  What wears when done too much is the springs in the female sockets, either on the wall or in the unit.

Any unit with a remote or those with low and high power states may have current flowing but at such a low current it's relatively safe to pull them.  Having just gone through a close thunderstorm I do _not_ do this however and rely on the switches in my conditioners when I'm around.  I'm not always around though.

I wrote about this practice a little here.

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