Bus Plugs Blog – Expert Safety and Usage Information

MIDWEST was asked why the total capacity of all the bus plugs connected to a 1600 amp bus duct was over 2500 amps. The particular facility had one 400 amp bus plug, four 200 amp, eight 100 amp, and twelve 30 to 60 amp bus plugs on the old bus duct.  These were mostly very old bus plugs and a few reconditioned or new bus plugs. Purchasing wanted to order two new 60 amp bus plugs but didn’t know how it was possible to have over 2500 amps connected to only a 1600 amp bus duct and then add more. Actually the equipment he wanted was no longer manufactured, so he would have to use old reconditioned or refurbished bus plugs. It was a maintenance man asking purchasing the question.  This was a case were the maintenance man was doing production equipment repair one day and electrical maintenance the next. But he was not an electrician by trade.  MIDWEST explained.  The size of the bus plugs is nominal. The actual fuse or breaker in the bus plug may have a lower rating. For example, a 100 amp bus plug may have a 60 amp fuse. Or 250 amp fuses in a 400 amp bus plug.  In addition, all connected load is not on all at the same time. There is a diversity factor. The diversity of an old or new bus duct system might result in only 50% loading. It would not be unusual for a 2000 amp bus duct to have less than 1200 amps on it. We get extremely nervous if the load approaches 80%. We see a huge increase in problems when this equipment is operating anywhere near full rating.  When we infrared scan a bus duct that is heavily loaded, the whole bus duct and many of the bus plugs just seem to light up under infrared. So usually old and new bus plugs and bus ducts are not loaded to full rating, but when they are, bad things start to happen. If the load is not known, it may be easy to spot measure the load on the bus plug feeders. Do this safely at the load. Do not measure load at the bus plugs. That would be extremely dangerous.  Always, safety first.

Buy FVK363R General Electric Bus Plugs

MIDWEST receives many requests from folks that want to sell us their used bus plugs. These requests come from all over the country.  Usually we ask for a little biography on their old bus plugs.  If we are interested, we may ask them to send us some digital pictures of what they have.  To recondition bus plugs, there is a huge difference in the cost between bus plugs that look like new bus plugs and those that have been painted several times and are damaged. Refurbishing damaged bus plugs is a waste of time.  Along with all this, there is a need to have a sense of humor. Just about all the folks that call MIDWEST are great people, but they sure don’t know our business.  Here is a recent quick example.  We received a call from someone wanting to sell us several pallets of like new bus plugs. They described them; Gave us some catalog numbers; And said they just want to get rid of them. We asked for some digital pictures and they were happy to accommodate.  When we reviewed the pictures, all their used bus plugs looked just great.  Perfect candidates for refurbished bus plugs. But the pallets were outside on a nice sunshiny day. Good light for great pictures. But it rains outside and bus plugs do not like rain.  We called the owners and they said their like new bus plugs were located in an area that was always warm and seldom rained. Seldom doesn’t mean never.  It means occasionally does. Occasionally means at least once and at least once means rust. And rust means disaster for bus plugs.  MIDWEST is not interested in rusty old bus plugs, even if they look like new bus plugs.