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Ground and Appliance Classes

Pinball machines commonly are classified as class 1 devices according to IEC 61140 (US) and EN 61140 (Europe). When building or modifying pinball machines you should understand which requirements need to be met for safe operations.


If you are unsure ask a professional electric engineer. This guide does not provide all information needed to design and operate a high-voltage/high-current system in a pinball machine. Use this at your own risk. Electricity can be dangerous and might kill you or burn down your house.

FAST Pinball has wiring guides for machines built on their platforms, but even if you're not using FAST Pinball hardware, there are some relevant ones here:

Video about ground:

Class 1 appliances

Class 1 appliances typically connect to a 3-prong AC connector which contains separate ground/electrical earth and neutral. They require that a single fault (e.g. a disconnected conductor wire touching the lock down bar of the machine) may not cause an electric shock. For that reason, all conducting parts need to be connected to the ground. In pinball machines, those are all metal parts such as:

  • Legs
  • Backbox connector metal parts
  • Speaker grills
  • Lockdown bar
  • Service door
  • Screws on the cabinet side

In a lot of cases braid copper wire is used to connect those parts to ground. You should test that a low-impedance connection between any conducting parts and ground exist. See Application classes for details.

Common Ground

If you operate more than one power supplies in your machine make sure to connect all their neutral connectors (N; 0V; commonly referred as ground). Funcionally, this is needed for logic components to maintain a common reference. Additionally, a floating ground might become dangerous when working with voltage multiple voltages. See Voltages and Power for details.

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