A. Piping

1.       Piping in boiler and mechanical rooms less than 1 1/4" (32mm) inside diameter.

2.       All other piping less than 2 1/2" (64mm) inside diameter. 

3.       All piping suspended by individual hangers 12" (300mm) or less as measured from the top of the pipe to the bottom of the support where the hanger is attached. However, if the 12" (300mm) limit is exceeded by any hanger in the run, seismic bracing is required for the run.

The 12" (300mm) exemption applies for trapeze supported systems if the top of each item supported by the trapeze qualifies.

B. Ductwork

1.       Rectangular and square and ducts that are less than 6 square feet in cross sectional area.

2.       Oval ducts that are less than 6 square feet (.5m2) in cross sectional area based on nominal size.

3.       Round duct less than 28" (.5m2) in diameter.

4.       All duct suspended by hangers 12" (300mm) or less in length as measured from the top of the duct to the point of attachment to the structure.  Hangers must be attached within 2" (50mm) of the top of the duct with a minimum of two #10 sheet metal screws.  If the 12" (300mm) limit is exceeded by any hanger in the run, seismic bracing is required for the run.

C. Suspended equipment

1.       VAV boxes and fan powered equipment weighing less than 50 lbs. (23kg) and rigidly connected to the supply side of the duct system and supported with a minimum of 4 hanger rods.

D. Electrical

1.   All conduits less than 2 1/2" (64mm) diameter suspended by individual hanger rods.

2.       All conduits suspended by individual hangers 12" (300mm) or less as measured from the top of the conduit to the bottom of the support where the hanger is a attached.  However, if the 12" (300mm) limit is exceeded by any hanger in the run, seismic bracing is required for the run. 

 
The 12" (300mm) exemption applies for trapeze supported systems if the top of each item supported by the trapeze qualifies.