Chiming in late this probably is obvious by now. The green wire is typically your safety ground you can loss it and the pin will work. So why have this? They changed the code and required that manufacturer use safety/cabinet ground. A good system has its components if conductive grounded.Voltage takes the path of least resistance any leakage or coin door grounded you feel a tickle well that's amperage flowing through your body you are part of the circuit. Never delete the 3rd prong on the cord, just change the outlet. If you have 3 wires feeding your outlet make sure it is grounded to outlet and box if metal. I also use a surge protector and use it like a switch to kill power instead of unplugging.

Everyone should also be aware that the ground plug on a lot of games is gone because it breaks off. I've had a ton of equipment that gets plugged and unplugged alot and had the ground just break off the cord and stick in the socket.

I know some people cut it off because they have 2 prong outlets or they're trying to fix a ground loop buzz or something else. But, I think most of the time it just breaks off. But, it obviously still needs fixing.

Jaz

P.S. In case anyone missed it in my MGC email a week or so ago, we will be checking grounds again this year. Any game that was designed to have a ground on the power cable must have a functional ground or the game will not be allowed on the arcade hall floor.

OK, maybe some pictures will help explain it better

electrical_11.gif
electrical_12.gif

Even more here in the UK as the games are 230v ac

One of the basic checks I do,at any of the shows I help sort power for is multimeter set on ac volts,and measure between one pinball and the other next to it.
If pin 1 to 2 = 0v
2 to 3 =100v
pin 3 to 4 = 100v
pin 4 to 5 = 0v that tells me pin 3 has an earth problem

Had the countless times and every time it's 100v ac give or take 10v
Numerous things,had earth cable off at line filter a few times,also with earth off in mains plug,also with bond to various pin parts becoming removed.

Also had the joy of 230v ac belt,because some pinhead had plugged in an old EM,that had NUMEROUS parts of the flex where the main cores were visible!!That could have been very nasty.Hence now,where I try and ensure a visual inspection of all flex cables before pin being plugged in

Just so people don't get bent out of shape about one other thing...

There are current, new device that are *DESIGNED* to be safe without a ground lug. It can be done and there are techniques to do that. The generic term is called "double-insulated" and it's beyond the scope to go into a whole lesson on electrical design.

So, don't worry if you buy something new that only has a 2-prong plug on it and think it might not be safe. There are multiple techniques of how to design an electrical device to be safe. Using a safety ground (also called "protective earth") (ie: the third prong) is one and there are specific thing you need to do to make use of it. There are also other techniques that don't make use of a safety ground.

Jaz

Yes, this is true, but I would recommend to always have the safety ground in a pinball machine. Most of the time the average consumer doesn't have their hands inside the device working on it. We pinheads on the other hand....

Williams "Fire"?

Textbook irony right there....

Funny, this thread reminded me of a time many years ago when I was working in an arcade and repairing pins. It was in Australia where we have 240v. I was working in the backbox of some SS pin and dropped a long bladed screwdriver down the hole into the cabinet. I grabbed the screwdriver but touched the metal blade as well. Bzzzzzzzt! It had dropped right onto the transformer below. Holy crap! It felt like I had a massive heart attack. It hurt like hell and I had to call it a day and go home early. :-/

I would love to hear this explained...

No true, 2 prongs are not grounded, the neutral is grounded by default at the panel but its not considered grounded. And hums have nothing to do with ground but the 60 cycles, etc. The 3rd ground is a safety for large items that have typically moving parts and contact with the user.
But ground has no bearing on hums, etc. I use a hum eliminator on some of my music stuff and some have ground lift but that is only the chassis to the rails of a rack, etc, etc.

Since the neutral is grounded at the panel you could say anything 3 or 2 would be grounded BUT only the neutral wire. Hence neutral.

Yes, me too. I am license electrician and never heard of a internally grounded tv or radio. Maybe a "double insulated" TV.

Yes, he is not understanding. I think he is referring to the fact that the entire neutral wire is bonded to ground at the panel. 2 wire prong devices are indeed, not "grounded internally". And, If either wire shorts to the chassis of your tv or radio, it becomes live and unsafe...hence the reason to add the 3rd wire ground.

That's the part that has always confused me, the whole ground and neutral being tied together in the breaker box. Doesn't that make the neutral and ground the same thing?

Yes, they are very much the same thing. The major difference between the 2 prong and 3 prong wiring scheme is that the extra wire allows a path back to the breaker box panel in the event that the chassis becomes electrified from a short circuit. If it wasn't there, you touching the chassis makes you the new ground path. Take another look at the pic in my earlier post in the thread. Read more about ground and neutral here:

http://en.wikipedia.org/wiki/Ground_and_neutral

When talking about safety grounds and double insulation, they are 2 different ways of achieving the same thing. That thing is protection from single fault failures causing a safety hazard.

A safety ground is one way of doing that. Double insulation (FYI, this does not mean insulation as in the plastic that coats wires) is another way of protecting from a single fault causing a hazard. How you design for safety without a safety ground would take pictures and way too much writing and reading.

Jaz

Going to have to give this a try on mine. This is good info. I've got all three prongs and just ordered a new cord so hopefully that fixes it. Will complete this test to.