thoughts on tapping long feeder to supply units

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electrofelon

electrofelon

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Cherry Valley NY, Seattle, WA
Another thread ("riser panel in condo high rise") I was reading got me thinking and intrigued about the method employed in it so I wanted to start a new thread to discuss the merits of this idea. Say we have a long building that has several floors and each floor has, say, 8 units. instead of running an individual conduit to each unit from the distribution point, what if we run one large feeder thru a J-box at each unit and ran taps off to a main breaker panel in each unit. Or course we would also assume that we didnt care about utility metering. It may actually work nice for sub-metering as the J-box could house the Ct's for the sub meter avoiding a big rats nest in the distribution panel. I am working on a mill convert to live/work where we ran 11/4 emt to each unit about 22 units total. I have another one coming up and am always looking for new methods to improve efficiency. Has anyone tried something along these lines and have any figures on relative labor and material costs? The first thing that came to mind is that if three phase feeds to each unit is desired, three phase main breaker panels would be required and that would be a huge price jump from MB single phase or MLO three phase panels. Second thought was the size of the feeders and the inefficient ampacity in large conductors and if parallel conductors were used, the increased cost of tapping in to parallel conductors. But on the other hand, it sure took some time to run and pull 22 long individual feeders.....
 
C

Canton

Senior Member
Location
Virginia
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Electrician
electrofelon said:
Another thread ("riser panel in condo high rise") I was reading got me thinking and intrigued about the method employed in it so I wanted to start a new thread to discuss the merits of this idea. Say we have a long building that has several floors and each floor has, say, 8 units. instead of running an individual conduit to each unit from the distribution point, what if we run one large feeder thru a J-box at each unit and ran taps off to a main breaker panel in each unit. Or course we would also assume that we didnt care about utility metering. It may actually work nice for sub-metering as the J-box could house the Ct's for the sub meter avoiding a big rats nest in the distribution panel. I am working on a mill convert to live/work where we ran 11/4 emt to each unit about 22 units total. I have another one coming up and am always looking for new methods to improve efficiency. Has anyone tried something along these lines and have any figures on relative labor and material costs? The first thing that came to mind is that if three phase feeds to each unit is desired, three phase main breaker panels would be required and that would be a huge price jump from MB single phase or MLO three phase panels. Second thought was the size of the feeders and the inefficient ampacity in large conductors and if parallel conductors were used, the increased cost of tapping in to parallel conductors. But on the other hand, it sure took some time to run and pull 22 long individual feeders.....
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As Augie pointed out..we have done the same with local metering at the panel. We were able to do it with one feeder feeding (6) small apartments because the calculated load was small. I have done other condo high rises that have a larger calculated load and this method was not feesible with the extra conduit runs for sub-metering.

Also the apartments layout and the logistics have a big factor in the best method of routing the risers and if you can move the feeders/taps to an accessible area.
 
electrofelon

electrofelon

Senior Member
Location
Cherry Valley NY, Seattle, WA
FWIW, the potential application I have would be a mill building. Everything would be exposed and surface mounted so not sure those factory riser panels would work very well. I envision the conduits running down the halls and thru a J-box where the taps could be made. I guess it all comes down to the load and the routing logisitics. The method is reminiscent of the old school way of doing things where there would be a long wireway and a bunch of disconnects tapped of its length. It is an interesting possibility Ill weigh out when this job gets moving.
 
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