Client had the electrical contractor test a few pallets of 10' sections of salvaged 480V 3Ph bus duct and asked me to review the results. I was directed by the manufacturer to follow NEMA Bulletin BU 1.1 which states:
"If readings of less than 1 Megohm for a 100 foot run (Megohms = 100/length of run of busway) contact the manufacturer." So I assumed that for a 10' length a reading of 10 Megohms or higher equates to this section being usable.
The contractor recommends to follow NETA Testing standard which requires 100 Megohms for a nominal 1000' run. When using the NETA formula (R1000 ft = Measured Resistance x Length of Run/1000) to adjust for a 10' length the required resistance is 10,000 Megohms.
Anyone familiar with these standards or testing busduct? I must be looking at something incorrectly for there to be this much of a difference between the two standard's requirements.
"If readings of less than 1 Megohm for a 100 foot run (Megohms = 100/length of run of busway) contact the manufacturer." So I assumed that for a 10' length a reading of 10 Megohms or higher equates to this section being usable.
The contractor recommends to follow NETA Testing standard which requires 100 Megohms for a nominal 1000' run. When using the NETA formula (R1000 ft = Measured Resistance x Length of Run/1000) to adjust for a 10' length the required resistance is 10,000 Megohms.
Anyone familiar with these standards or testing busduct? I must be looking at something incorrectly for there to be this much of a difference between the two standard's requirements.
