Stage pin versus NEMA 5-15 (Edison) connectors
The primary advantage of the stage pin connector over the NEMA 5-15 connector (commonly known as an Edison plug) is its increased durability and resistance to damage due to its more robust construction and the ability to compensate for wear with a pin splitter. Having a distinct connector designated for dimmable power also helps prevent confusion of dimmed and non-dimmed circuits which could lead to equipment damage. Even the smallest stage pin connectors are rated for 20 A, which translates to 2.4 kW at 120 V, compared to the 15 A and 1.8 kW of the NEMA 5-15.
Despite the advantages of stage pin connectors, many smaller installations use Edison connectors due to their availability and the ease of connecting equipment to outlets already available in a building. This reduces refit costs, particularly when small portable dimming packs (often 4×1.2 kW channel models) are used. Such installations may also use inexpensive store-bought extension cables, though care must be taken to ensure that the ratings of such extension cables are not exceeded.
Though the initial cost of constructing a 12/3 stage pin extension cable is higher than simply purchasing an equivalent edison extension cable, the maintenance costs of the former are ultimately lower for several reasons. To begin with, less maintenance will be required as a result of the more rugged construction. When maintenance is required, many cable faults may be repaired by disassembling the connector, replacing broken components with spares acquired by cannibalizing other broken connectors, trimming away defective sections of cable, and reapplying the connector to the cable. This sort of repair is not usually possible with Edison connectors, particularly the factory-molded type. If a connector is beyond repair, a new stage pin connector is often less expensive than a replacement Edison connector when purchased from local vendors.
SafetyThough 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.
Other connectors used in theatre applications Many theatres also use Edison plugs, which are the standard connector used in homes and businesses in North America, because of their availability and the ability to connect household fixtures to a theatrical control system. Twist-lock connectors are used in many theatres because of their locking feature, which will not allow fixtures to become accidentally disconnected. It is important to note that all connectors used to power lighting fixtures must be rated at 20 amperes or higher, depending on local electrical codes. Temporary high-power distribution wiring often employs camlock connectors to connect dimming equipment, power distribution units, controllers for motorized chain hoists, and other high-power equipment to a company switch, generator, or other tie-in point.
UK theatrical lighting installations normally use the BS 546 type plug rated at 15 A (the higher phase voltage of 230 V allows lower currents for the same power) or occasionally IEC 60309 16 A industrial plugs. Most dimmer racks also use IEC 60309 32 A or 63 A plugs on the non-dimmed side.