Two-part question. I?m working on a 5000sqft. renovation. Most of the work consists of custom built-in cabinetry, two baths, basement wet bar and outside lighting. I haven?t done a load calc. yet since I?m waiting on some cut sheets but some additions of significance are: a sauna, washer and electric dryer, well pump, fountain pump, dishwasher, ice maker, under counter sub-zero, ejection pump, a few HID perimeter lights and home theater amplifiers. The existing service is 300A. It?s fed with 350 KCMIL XHHW Aluminum from the transformer. Meter Pan is rated 400A max/320A continuous. Out of The load side of the meter they ran two separate sets of 4/0 aluminum feeders in a 2 1/2? PVC pipe that terminates in a trough. From the trough one set of conductors feeds a 150A main breaker panel through a nipple?the other set feeds a 150A disconnect through a short nipple. This disconnect feeds a 150A main lug on the second floor. The main breaker panel also feeds a 100A sub in the basement.
Before adding any additional load ,most, if not all, the lights dim drastically when the AC compressors kick on. When I consulted the inspector about this dimming problem before I even added more load to the service he suggested I parallel the two separately run feeders and then tap off and feed my panels.
When he first mentioned this it seemed to make sense?paralleling the 4/0 Al?s would allow for less voltage drop I thought. It would also rate each phase at 400A but since the service is only being fed with 300A (# 350 KCMIL Al?s) this seems to be of no advantage. Now I?m thinking that this 60 or so foot run from the load side of the meter to the trough wouldn?t be subject to significant voltage drop anyway.
Well, I did follow his suggestion but I?m now concerned I may have violated the code. What I did was parallel the 4/0?s in the trough and tapped off each with 2/0 cu to each adjacent main breaker panel. (BTW, in place of the 150 A disconnect, I installed a 150A main breaker panel to which I added a 125 A breaker to feed the 2nd floor sub.) I?ve never had to tap before and I?m unclear about the sizing of the taps especially when not fused. It seems to me now that the taps should be rated based on the service size. Would I then have to use 250 KCMIL cu to feed these 150A mains? I don?t think the lugs would even accept it.
Lastly, what suggestions would you have to eliminate the dimming of the lights? Could it be as simple as separating the air condition compressor circuits from any lighting circuits by putting them in there own panel? Or could the root of this be that 300A?s with 350 KCMIL Al?s is simply underrated? The homeowner and I both want this done correctly and cost is not a major issue for him. With all the additions, would it warrant a complete service upgrade? I really want to improve the power distribution and over power quality. He also has added 5 computers 4 plasma TV monitors which need "clean" power.
I would greatly appreciate any detailed suggestions.
Thanks, Darren
Before adding any additional load ,most, if not all, the lights dim drastically when the AC compressors kick on. When I consulted the inspector about this dimming problem before I even added more load to the service he suggested I parallel the two separately run feeders and then tap off and feed my panels.
When he first mentioned this it seemed to make sense?paralleling the 4/0 Al?s would allow for less voltage drop I thought. It would also rate each phase at 400A but since the service is only being fed with 300A (# 350 KCMIL Al?s) this seems to be of no advantage. Now I?m thinking that this 60 or so foot run from the load side of the meter to the trough wouldn?t be subject to significant voltage drop anyway.
Well, I did follow his suggestion but I?m now concerned I may have violated the code. What I did was parallel the 4/0?s in the trough and tapped off each with 2/0 cu to each adjacent main breaker panel. (BTW, in place of the 150 A disconnect, I installed a 150A main breaker panel to which I added a 125 A breaker to feed the 2nd floor sub.) I?ve never had to tap before and I?m unclear about the sizing of the taps especially when not fused. It seems to me now that the taps should be rated based on the service size. Would I then have to use 250 KCMIL cu to feed these 150A mains? I don?t think the lugs would even accept it.
Lastly, what suggestions would you have to eliminate the dimming of the lights? Could it be as simple as separating the air condition compressor circuits from any lighting circuits by putting them in there own panel? Or could the root of this be that 300A?s with 350 KCMIL Al?s is simply underrated? The homeowner and I both want this done correctly and cost is not a major issue for him. With all the additions, would it warrant a complete service upgrade? I really want to improve the power distribution and over power quality. He also has added 5 computers 4 plasma TV monitors which need "clean" power.
I would greatly appreciate any detailed suggestions.
Thanks, Darren
