Sounds really safe. Do you do this on all your games?

I always add a 3 prong power plug too and run the ground to the transformer lug. But that’s all I do. Maybe this should be in the confessions thread.

I've never seen the need to add a ground to a game that didn't have one. Or I'm just lazy or cheap. The only shock I ever got is if the fish paper on the flipper switches was gone, but that might happen anyway?

I think I may have an idea what Odin looks like.

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I have gotten shocked on side rails before, not sure what voltage was on them but enough to not want you hanging on, so it would be a good idea to do it.

Rails are where I put my hands to brace myself when I lean into a cabinet to fiddle with something. Many times I’ve done this and gotten minor tingles when a finger brushed against line voltage accidentally. If the rails were grounded, those tingles would have been potentially lethal.

Actually to be totally safe the machines should be plugged into GFCI's, ground fault interrupters, if the rails are grounded then that's all you need, if not, then you need to ground them. If you have a relatively modern house that has the center ground lug on the receptacles(and that lug is actually grounded) then you can just buy a GFCI unit and plug it into the wall and then plug your surge protector into that in case there is a lightning strike, the higher Joules rating the better.

I plug all of my games into a GFCI protected circuit. If the “what goes inta” doesn’t equal the “what goes outta”, it trips. I trust this life saving device more than my ability to ground every metal part in a pinball game.

With respect, while I agree with the importance of GFCIs, they don't provide total safety. If your body completes a circuit inside the machine and not to ground, GFCI won't notice.

Somebody gets it!

I believe the machines are correctly designed as they are.

Yes.

Like how many appliances or other electronic devices that came with a two prong plug do people take apart and add a three prong plug and make sure every metal part is now grounded?

When I was a kid, there was this arcade at a pool. People played EM pinball machines, barefoot on wet floors and as far as I know no one ever got fried.

Now, I certainly wouldn't recommend that craziness but I've only ever owned 2 or 3 machines that came with grounded power cords.

If the two prong plugs were safe enough for pinball manufacturers and arcade owners liability, they're good enough for me.

I thought intentional grounding was for football.

Seriously, I've never had a problem except for a slight, slight, slight shock when working on my pins, which are not grounded. And that’s only happened once, maybe twice, in the 4 years I've been in the hobby. However, I don’t think I’ve ever touched line voltage in the process, my one or two slight shocks were probably with 24V or 50V. After seeing this debate previously, I’ve gotten the impression I should leave EMs ungrounded.

This worked when the games were new, the fisch paper was perfectly intact, the wiring insulation was clean and pliable and they hadn't been exposed to decades of questionable repairs. Now as the games are getting older a bit more caution might be prudent. I'm working on a King of Diamonds right now and was contemplating doing the exact same grounding as the original poster outlined. I had the same question about the side rails. The different schools of thought are interesting to follow.

The good news is periodically some asks here in Pinside about fatalities servicing or playing a pinball and no one knows anyone that has passed from what we are discussing. Shocked themselves hell yes (not me I wouldn’t do that).

Voltage here in the UK is 240v. As a matter of course, I run a 3 core mains cable ( live, neutral and earth) into the machine. I run the earth to the transformer, and (Gottlieb in particular) an earth to the coin door and lock-down bar. I also put heat-shrink tubing on the flipper connecting rods, and replace the fish paper with flexible plastic on the replay button. I dont bother earthing legs or side rails as they are mounted onto wood with no electrical connection. I've been doing that for years without issue.

I couldn't find any instances of someone being killed by a pinball machine, but apparently 450 people die every year from falling of of bed. So you could increase your odds by leaving the pinball machine alone and spend that time installing bed rails.

I feel little tingles from the rails when I'm working between two machines all the time, doesn't feel like very high voltage. But I'm not about to start fooling around with things like adding non-original grounding or changing plugs to 3-prong that were originally two. My place has grounded sockets if they do have three and those ground interruption thingees. I did get a 25,000 volt but extremely low amperage zinger while electronically restoring a 1960s color TV once and slammed my head into the top of the cabinet, learned my lesson on THAT one!

But if earthing wasnt necessary, then why do some later EMS have factory fitted earthing cables?
Sorry, but if all between me and my maker is a piece of 40 odd year old tired fish paper, then I'll earth all metalwork that could carry mains voltage. Lifes too short as it is!

UL used to be OK with two prong commercial machinery, but those days are long past. They made the calculation that the machine should fail safely (it's grounded, wiring spacing controlled, certified materials, etc.), but does not need to protect you from some other defective thing (the game next to yours with the 120VAC at the rails). Makes sense as the designers have no idea what will be around their game. So that's how you get the situation that your game can complete the path to ground from some other game.

Just be lucky you live in a place that allows you to change your own plug (local regulations may vary). Many countries you can't change a plug, only a whole (molded plug) cord. And you must be an electrician.

Don C.