Switch-Rated Plugs and Receptacles Give Edison Welding Institute Flexibility and Efficiency

At the Edison Welding Institute (EWI), the need to continually move welding equipment between more than 100 different work stations made it difficult to quickly and safely disconnect electrical power each time. By installing a combination plug/receptacle and disconnect switch at each location, EWI has been able to save time, gain greater flexibility and improve safety. Meltric Switch-Rated plugs and receptacles, now used at the facility, allow workers to safely make and break electrical equipment connections, even under full load.

EWI is the leading engineering and technology organiza-tion in North America dedicated to the applied research and development of materials joining and welding. It pro-vides expert materials joining assistance, as well as research, consulting and training, to its members in the aerospace, automotive, government, energy and chemical, heavy manufacturing, medical and electronics industries.

Its 40,000 sq. ft. high-bay laboratory provides the space to set up individual work stations for a large number of projects simultaneously. Three 1,600 amp bus bars pro-vide 480 volt power throughout the laboratory, with more than 100 separate power drops for welding power supplies.

Because of the nature of EWI’s assignments, workspace layouts and equipment are constantly being rearranged. Manager, Welding and Testing Labs Andy Joseph says, ”We have nearly every one of the recognized welding processes commonly used today, and they all require electricity. The equipment for all these different proce-dures takes space, but we’re not using them all at the same time, so we need to be able to change them out.” Previously, fused disconnects were attached directly to the overhead bus bars, with pin-and-sleeve connectors at the work stations. Safety was a concern because the dis-connects were located at the ceiling level. Joseph explains, “We had to use a 20-foot pole with a hook on the end to turn off the power to a plug. Disconnecting live would have been an unsafe option.” From a safety standpoint, he adds, there was no way to disconnect quickly if someone was getting hurt.

As a remedy, EWI first considered installing disconnect switches at ground level for each location. This still would have required the pin-and-sleeve plugs to connect the equipment, and the switch boxes would have taken up valuable space. Joseph notes, “With 120 of the old con-nectors, we would have had to buy 120 disconnect boxes that would have required extra wiring.”

Instead, Joseph selected Meltric’s Switch-Rated plugs and receptacles, which combine the two functions. Now with Switch-Rated devices installed at more than 100 locations in the lab, disconnecting power is a simple and safe operation. Pressing a push button off-switch on the receptacle breaks the circuit and ejects the plug to its rest position. Then the plug can be withdrawn from the receptacle in complete safety, since the circuit is already dead. When the plug and receptacle are separated, de-energization can be visually verified, and a safety shutter on the receptacle prevents access to live contacts.

Safety was the key factor in the decision to use the Switch-Rated plugs and receptacles. According to Joseph, simplified compliance to the NFPA 70E Standard for Employee Workplaces was an additional benefit to using Switch-Rated devices. He says, “With the disconnects over-head, we would have had to suit up with PPE (personal protective equipment) because there was no way to verify that the power was disconnected without someone going up in a manlift. Having the disconnect switch right in the plug eliminates the need for an arc flash hazard assessment or suiting up.”

In addition to safety, the plugs and receptacles provide greater flexibility in EWI’s operations. Joseph points out, “We have a limited amount of space and are continually changing out equipment for different projects. When we start or finish a project, we can pull out one setup and bring in another quickly and safely.” Approximately half of the laboratories are set up for systems welding, with the other half divided between arc welding and laser welding. Joseph explains, “We may have to move one technology into another area, and the Switch-Rated plugs and receptacles make that very simple.”

Another benefit, according to Joseph, is the easier installation of the plugs and receptacles compared to the previous pin-and-sleeve connectors. He says the devices offered a relative cost savings because of the inconvenience of installing the former connectors. “They required soldering,” he notes, “and we are constantly swapping equipment in and out. Changing the Switch-Rated plugs and receptacles is a timesaver by comparison.”

They are used on other applications as well. In addition to the welding power supplies, EWI uses auxiliary equip-ment such as hoists, wire feeders, fume extractors, weld-ing positioners, robotics, and travel carriages. Joseph says he purchased 20 each of Meltric’s 20 amp and 30 amp Switch-Rated plugs and receptacles for these applications, all rated for 480 volt operation.

In summary, Joseph states, “Probably the biggest benefit for us has come from efficiency improvements. Previously, because of the difficulty with making discon-nects during a changeover, we would leave workstations set up because it was hard to take them apart and put them back together. This made floor space hard to come by. It also caused some turf wars on how space was being used. Now, changeouts are easier to accomplish, we have a more presentable area, and the engineers and technicians don’t have to worry about someone else tear-ing down their workstation because it is easy to set up again.”

The Switch-Rated plugs and Receptacles used at EWI were provided through Meltric distributor Johnson Electric Supply, of Columbus.