You're right, a simple on/off switch with three terminals labeled "Line," "Load," and "Ground" does seem strange and potentially like a short circuit waiting to happen. Here's the breakdown of why you're seeing that and how it likely functions in a golf cart lighting setup, along with some of the common reasons you'll see 3-terminal switches.

The "Ground" Terminal Is Likely NOT for Direct Grounding to the Chassis

This is the critical point. You're thinking of the ground terminal as a direct connection to the golf cart's frame or negative terminal of the battery. That's probably not what it's doing. Connecting the positive "line" to a direct ground would cause a dead short.Instead, the "ground" terminal is most likely for one of a few possibilities: A Grounding for a Pilot Light or Indicator

Many on/off switches include a small LED that illuminates when the switch is on. The "ground" terminal is specifically for powering this LED. The internal wiring of the switch connects the "load" side through the LED to this ground terminal. So, when the switch is on, the LED gets power, and when the switch is off, the LED is unpowered. This is the most common use.

A "Position" Switch

Some 3-terminal switches might have internal wiring for a specific purpose. It's less likely in a simple on/off switch for lights, but possible. In this case, the "ground" terminal might be connected to the "line" through a resistor when the switch is in the "off" position, signaling a different state to a control module.

A Faulty Label or Misunderstanding

It's possible the switch is mislabeled. Maybe it should only have two terminals, and someone has incorrectly labeled the third.

How to Confirm What The "Ground" Terminal Does1. Visual Inspection

Look very closely at the switch body. Is there any indication of an LED or other component associated with the "ground" terminal? Sometimes a tiny LED window is visible. Can you see any internal wiring if you look closely at the terminals? Does anything visibly lead from the "load" side to the "ground" terminal?2.

Multimeter Testing

This is the safest and most reliable way to know for sure.



Switch OFF

Measure the resistance between the "Line" and "Load" terminals. It should be very high (open circuit). Measure the resistance between the "Load" and "Ground" terminals. If it's a pilot light, you'll likely see a relatively low resistance (e.g., a few hundred ohms) corresponding to the LED. If it's not a pilot light, you'll probably see a very high resistance (open circuit). Measure the resistance between the "Line" and "Ground" terminals. It should be very high (open circuit).

Switch ON

Measure the resistance between the "Line" and "Load" terminals. It should be very low (near zero ohms). Measure the resistance between the "Load" and "Ground" terminals. If it's a pilot light, you'll still likely see a relatively low resistance. If it's not a pilot light, you'll probably see a very high resistance. Measure the resistance between the "Line" and "Ground" terminals. It should be very high (open circuit).

Correct WiringAssuming it's a standard on/off switch with a pilot light feature:1.

Line

Connect the positive (+) wire from your battery (or the output of your key switch, if the lights are only supposed to work when the key is on). Make sure to include a fuse in this line, as close to the battery as possible.2.

Load

Connect the wire that runs to your lights. This is the positive (+) side of the lighting circuit.3.

Ground

Connect the wire from the "ground" terminal to the negative (-) side of your battery or the golf cart's chassis ground. This only powers the pilot light, not the main lighting circuit.

Important Safety Notes



Fuses

ALWAYS use fuses in your wiring. A blown fuse is much better than a fire.

Wire Gauge

Use wire of the appropriate gauge (thickness) for the current your lights will draw. Consult a wiring chart to be sure.

Polarity

Be absolutely sure you know which wires are positive and negative. Reversing polarity can damage components.

Battery Disconnect:* Disconnect the golf cart's main battery before doing any wiring.By carefully testing the switch with a multimeter, you'll be able to determine exactly how that "ground" terminal is intended to be used and wire it safely. If you're still unsure, take pictures of the switch, including any markings, and the area where it's located, and I might be able to provide more specific advice. Flag for review