Safety
Though stage pin connectors are usually used in part to distinguish dimmed circuits from non-dimmed Edison circuits, newer theatrical installations may have several dimmed circuits that terminate in Edison outlets at various locations for convenience; thus care must be taken to avoid using these circuits for non-dimmable equipment. Connecting certain non-dimmable appliances or equipment to dimmed circuits may result in damage to the dimming equipment or the downstream device.
Most modern stage pin connectors feature a ground pin that is longer than the line and neutral pins, ensuring that the ground connection is made first, and thus the safety ground is in place before line voltage is applied to the downstream equipment.
As an added precaution, some SPCs are built with a clear housing on one side. This allows a user to confirm that they are wired correctly before connecting them.
On some older female pin receptacles, the electrical contacts are not deeply recessed in the plug body and can easily be accidentally contacted resulting in an electric shock if the circuit is live. This was one advantage of the Edison outlet in that it was impossible to contact live parts unless something conductive was inserted into the slots. New connectors have the contacts deeper inside the body.
A major disadvantage to this style of connector is that it can be mated with one connector reversed, reversing ground and line connections. For equipment mechanically attached to grounded building structures such as a lighting instrument mounted to a batten or grid this will cause a line-ground short circuit. For equipment not attached to a building ground, such as a floor-mounted lighting instrument, this condition will cause the chassis of the equipment to become electrified creating a shock hazard. Care must therefore be taken to avoid misaligning plugs. It is also possible to mate stage pin connectors such that the ground pin is inserted into the neutral socket and the neutral pin is inserted into the ground socket, but this mistake does not usually result in a fault condition unless there is a hot-neutral reverse upstream in the cabling.
Read more about this topic: Stage Pin Connector
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