Bonding of bolted connections on structures, cable trays, etc.

[joshtrevino]

Does a bolted connection on a structure create an NEC acceptable bond between the two pieces of the structure bolted together? The structure in question is steel (may be galvanized).

Also, is it required to install a bonding jumper at each joint of a cable tray?

Any code references would be appreciated.

 

[Gregg Harris]

Does a bolted connection on a structure create an NEC acceptable bond between the two pieces of the structure bolted together? The structure in question is steel (may be galvanized).

Also, is it required to install a bonding jumper at each joint of a cable tray?

Any code references would be appreciated.

Take a look at 392.7 and then visit 250.96

 

[suemarkp]

392.7?? Maybe [2011] 392.60?

 

[Gregg Harris]

392.7?? Maybe [2011] 392.60?

.7 is 2008 and .60 is 2011

 

[joshtrevino]

250.96 (A)
"Metal raceways, cable trays, cable armor, cable sheath, enclosures, frames, fittings, and other metal non-current carrying parts that are to serve as grounding conductors, with or without the use of supplementary equipment grounding conductors, shall be bonded where necessary to ensure electrical continuity and the capacity to conduct safely any fault current likely to be imposed on them ..."

This leaves open the question of whether the bolted connection ensures electrical continuity and the capacity to conduct safely any fault current. Is it good practice to bond all cable tray joints with jumpers? This seems like it could get very expensive if the mechanical continuity of the tray sections (bolted connections) would provide the necessary electrical continuity. Thoughts?

392.7(B)(4) (2008 NEC) seems to indicate that "bolted mechanical connectors" are adequate for cable tray section bonding.

 

[Gregg Harris]

250.96 (A)
"Metal raceways, cable trays, cable armor, cable sheath, enclosures, frames, fittings, and other metal non-current carrying parts that are to serve as grounding conductors, with or without the use of supplementary equipment grounding conductors, shall be bonded where necessary to ensure electrical continuity and the capacity to conduct safely any fault current likely to be imposed on them ..."

This leaves open the question of whether the bolted connection ensures electrical continuity and the capacity to conduct safely any fault current. Is it good practice to bond all cable tray joints with jumpers? This seems like it could get very expensive if the mechanical continuity of the tray sections (bolted connections) would provide the necessary electrical continuity. Thoughts?

392.7(B)(4) (2008 NEC) seems to indicate that "bolted mechanical connectors" are adequate for cable tray section bonding.

Bolted connections are fine provided all paint, oil, corrosion etc.are removed when assembling.