Recently an innovative Bridgeport grounding product saved the day for an electrical contractor. The contractor had wired a new electric room for a hospital lab but the job failed inspection because of improper bonding.
The contractor was required to install rigid metal conduit to protect the grounding electrode conductors (GEC) from physical damage between panels and the grounding electrode. The NEC requires the ferrous metal raceway (RMC) to be electrically continuous and be bonded at both ends of the raceway with the same or larger size wire to ensure the raceway and GEC are in parallel.
These raceway-bonded connections are necessary so the ferrous raceway does not create an inductive choke on the grounding electrode conductor; in other words, produce resistance to the grounding systems path to earth [NEC (Articles 250.64(E) and (Exhibit 250.28)]. For this particular hospital project, the grounding electrode conductor needed to be #4/0 per NEC (Article 250.66).
The contractor used a one-inch grounding bushing with #14- #4 AWG size grounding lug and #4 AWG bonding jumper. But because one-inch grounding bushings with 4/0 lugs were not available, the contractor was faced with the possibility of a major rework job.
Fortunately, the project's AHJ inspector remembered seeing Bridgeport's Mighty-Bond® Equipment Grounding Hubs at an IAEI conference and recommended the solution. The contractor immediately placed an order with a Bridgeport distributor. Once in hand, using Bridgeport's one-inch MCH-100 Equipment Grounding Hub, it took just under an hour to install and pass inspection!
The Mighty-Bond MCH-Series Rain tight Grounding and Bonding Hubs are part of Bridgeport's full range of electrical fittings and can be found in the "Wall of Orange™" – a completely stocked selection of quality electrical fittings and innovative product solutions available from your local electrical distributorship across the U.S. and Canada.
For more information, visit http://www.bptfittings.com.
SOURCE: Bridgeport Fittings