Reusing Conduit
Reusing Conduit
(OP)
I know that there are calculations to determine the minimum conduit size required for conductors, but is there also a maximum size that can be used? I am replacing a handful of 208V,3 phase rooftop units. The new units have significantly less load than the existing. Therefore lower rated circuit breakers and wire sizes will be used for the new units. I would like to reuse the existing conduits if possible. In a few cases the existing conduit size meets the size of the required load, but in most cases, the existing conduit is 1 to 2 inches larger than the minimum conduit size required for the load. Length of the run varies between 50-175 feet. Can over sized conduits be used? or is there some issue with insulation or something else?
example: existing rooftop unit: 350 mcm wire size, 2-1/2" conduit, and fed by 300A circuit breaker. The new rooftop unit has an MCA of only 34A and a recommended 35A MOCP device. Thus #8 wire will be installed and only 3/4" conduit is needed. Can the 2-1/2 inch conduit be reused?
Thank you.
example: existing rooftop unit: 350 mcm wire size, 2-1/2" conduit, and fed by 300A circuit breaker. The new rooftop unit has an MCA of only 34A and a recommended 35A MOCP device. Thus #8 wire will be installed and only 3/4" conduit is needed. Can the 2-1/2 inch conduit be reused?
Thank you.






RE: Reusing Conduit
RE: Reusing Conduit
Steve Wagner
RE: Reusing Conduit
http://www.polywater.com/jamming.html
RE: Reusing Conduit
RE: Reusing Conduit
Depending on your code, you may have to add a code sized grounding conductor if one is not present.
For the most econoical installation;
1> I would reuse the existing conductors if the grounding is up to code.
2> If an equipment grounding must be added, I would remove the existing conductors and install the new conductors with the grounding conductor. Reclaim and sell the old copper to offset the cost of the installation.
respectfully
RE: Reusing Conduit
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com
RE: Reusing Conduit
RE: Reusing Conduit
"Whenever you are asked if you can do a job, tell them, certainly I can! Then get busy and find out how to do it." Theodore Roosevelt.