So I'm just showing my son the EBD-LE I just got working as he was visiting for a bit and a brushed my hands between that and the Dr Who sitting across from it. I got a jolt but was luckily able to pull back. I knew that was electricity. Pulled out my DMM and surely enough rail to rail from the EBD to the DR Who (on two different plugs in the room) read just above 120 volts. Guess I'm lucky I just brushed and didn't get more of a shock.

At any rate, I haven't pulled plugs but considering that neither game has ever given me a shock I'm guessing before looking into it that someone swapped the wiring and that perhaps one of the floor plugs has hot wired to the common plug so that the ground for one side of the room is actually the hot for the house. Any other ideas on why my rails are wired to power more machines?

Checked the wall plugs already. Proper continuity between neutral and ground there so has to be an issue with one of the machines. Frightening really.

Theoretically yes, however it is an old house and only the newer wiring I have added has three-wire romex going to it. This excludes much of the wiring in this room, unfortunately. I really need to add some wiring but can't owing to the location of the room. I mostly have to check what is there but it is starting to seem to perhaps be an issue with one of the machines, though I could see two wire wiring that was 'backwards' or reversed polarized causing the issue.

Don't know why that test didn't occur to me. 60 volts differential on the same circuit. Definitely an issue with one of the machines. Okay, so this is weird. Put another game on then tested between the three - no voltage between any and they read continuous. Plug the other back into the wall and voila 120 volts plus rail to rail. So I try continuity between grounds from one wall to the next and as I suspected, continuity chirps at say about 60 hrz chirp. Hmmmm, sound like one of those outlets is wired house hot to ground. Don't understand the 60 volt thing, but when they are on the same circuit no problem, and theoretically I shouldn't ever get 240 as long as both rails are on ground, so now I have to pull the plates on those tomorrow and try to figure out which is wired backwards. That would seem to be the issue since all machines ground to each other on the same circuit.

Yeah, but the question here is, if the wiring is two wire, can I safely power these games or not. Rewiring this particular part of the house is not, unfortunately, an option. Funny thing here is that in the house power box, the neutral and ground wires are actually connected. The little cheap trick to fool testers is really a shorter version of the same thing. Usually with lower rated wire mind you.

Well, as I suspected from my chirping ground to ground, the suspect socket had the white and black swapped. I figured if that was the case, since ground tied back to where it should, that it meant that the socket must also be locally tied, ala Vid's description. I figure that the other sockets were similarly wired to tie neutral into ground as they test continuity between the neutral and ground, only on this occasion neutral and hot were swapped. I'll be picking up some GFCIs tonight for sure. Sure enough, pulled the socket:

2014-03-25 17.18.49.jpg

GCFI replaced that socket but I am a bit concerned that I don't know have a proper ground wire. Not really feasible to add in this location either. Any concerns using the machines here if GCFIs are installed in the requisite sockets?

There wasn't a problem with the pins. I knew there wasn't for sure when I plugged them both into the same socket and had no voltage from 'rail to rail'. I also figured almost immediately, knowing the age and some of what I've found in the house that it was likely that someone just wired things backwards (hot to neutral/vice versa). That is what I found. Wiring in the machines was fine. I replaced the outlet with a GFCI - properly wired. I have two more to replace the others in my house and plan to do the same.

I bought a tester but haven't opened it as I figure I'll just take it back. I'd rather do a visual inspection of the wiring in the older sockets I haven't been in as I am now concerned this might be a problem elsewhere. Additionally, I want to make sure the trick they used in the pic I posted - wire from neutral to ground on the outlet - wasn't used elsewhere so I'm going to probably have to purchase a few more GFCI outlets. Little cost considering the potential for personal harm or house fire. I've been in the house for eight years, added wiring here and there and know that there was some suspect wiring in places. I added new breakers and circuits just for my electronics in the front rooms because I was concerned about grounds but with pins drawing more amps, and players touching metal surfaces that are supposed to be grounded I want to be extra safe.

I'm really just lucky this didn't happen after I had been jogging or with people over.