Originally Posted by Doug Blackburn
You can't even feel an 8000 volt static discharge. The ones you feel start at more than 10,000 volts and go well above that. On top of that few source components today have the chassis grounded - only the hot and neutral are connected through the power cord interface. Even Japanese AVRs with 7 amp channels rated at 150 watts each only have 2-wire power cords.
There may be some possibilities for touching something near your equipment before you touch the equipment itself - the bigger it is and the more metal in it the better you'll discharge yourself.
I don't like zapping electronic components repeatedly -- you just don't know what might happen. Fortunately, my racks have metal legs and I just make sure to discharge myself to a leg before touching anything.
If you have nothing near the equipment you can discharge yourself to, you can always make a grounding spot by conneting a piece of thin copper or brass bar to a wire connected to the ground outlet on any wall socket. If you want additional safety/protection, put a 100,000 ohm 5 watt (higher watt rating is fine but not necessary) resistor in series with the wire connected to your brass or copper ground strip. Place the grounding strip somewhere convenient and train yourself to touch it first.
When there is a 2-wire power cord the chassis is supposed to be isolated from the electronics which SHOULD make the static discharge a non-event, but it's hard to know exactly what happens in every case... can the static jump through a plastic or membrane switch button and allow the high voltage to get into a switch circuit? Maybe... maybe not.
Also, the characteristic damage caused by a static discharge is rarely instantly fatal to the electronics. If there is damage it can be there for weeks, months, or years before a failure happens. It's best to just avoid the discharges as much as possible - one of those "better safe than sorry" measures. Like using a good power conditioner.
Sure if you are that worried about it you can go to extremes but it really isn't necessary. Discharging yourself to a metal rack is a very good idea and isn't an extreme measure. It's easy enough and doesn't cost anything. Take off your slippers and make sure your house has enough humidity in it to minimize it if you live in a dry environment. You'll be upgrading the player long before a component dies. It could happen if its a bad design but usually ESD testing will flush out problem designs. Most will pass much higher levels because the discharge is to the chassis. Usually one component has a safety ground and the energy will pass via the shield on the cables to the device and dissipate to ground. If none of the components are grounded then you probably will not feel anything. You basically build up a charge on the player or system until it dissipates by some means.
If the room is dry you can feel 8KV and its in the winter months when we all sometime feel this discharge. Unless you live in the dry southwest USA where even in the summer you can shock yourself all day long. You are correct that sometimes especially with slippers you might build up a charge over 20KV. The requirement during test is to have 30% humidity levels or higher while running ESD testing and you can still see a discharge very easily at 8KV. I can feel it if I zap myself by accident. Also we run 20 positive and negative discharges in all locations we think it could potentially enter the electronics. Basically all plastic locations where you may touch the product like knobs and buttons. There is also a contact discharge requirement that covers all the metal surfaces. I've tested one sample over and over and they will not break as long as most of the energy has a path to ground that is not through the electronics. So you really are not hurting the product in most cases. So don't get too worried about it.
I've worked in product design and tested for EMC requirements since the early 80's. I've even worked in a test lab and tested many different product types and even those with no ground for its power supply. Most products when designed correctly will be just fine with many thousands of ESD strikes. Much more than you will ever give that product during its life while you use it. There are a few products out there that are not but if it dies with a zap from walking on your carpet and touching it then it's time to get a different player IMHO. When I have a product tested it goes through a few thousand ESD strikes and I use the same product to test an option again and again. Very rare I have a failure! If I do it's after only the first few strikes on a new product and then the product is debugged to see where the path of that strike is getting into the electronics and its redesigned to minimize the amount of energy that passes through the electronics.
Today's electronics are very robust at surviving ESD events.
I myself try to minimize ESD just because it can hurt when it happens. That's the real reason why I like to minimize it.