Joining Branch Conductors

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textmi

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EC
I have (2) branch conduits serving (2) pieces HVAC equipment in the the same location fed from the same panel. We are now adding replacing the two units with (1) unit that is more sensitive to voltage drops and is having issues with errors and shutdowns. The original branch conductors are not sized to provide less than 5% total voltage drop recommended by NEC although the equipment manufacturer allows up to +-10%.

Is it allowable to use join the two separate branch conduits to feed (1) piece of equipment using (1) OCPD to reduce the voltage drop?
 
Paralleling conductors to use under a single overcurrent device has it's own set of rules as far as conductor size, length and characteristics.

Seeing as how you had mentioned "branch circuits" instead of "feeders" to the unit it's probably unlikely you'd be able to combine the 2 under 1 OCPD but not sure of your exact circumstance.


JAP>
 
textmi said:
I have (2) branch conduits serving (2) pieces HVAC equipment in the the same location fed from the same panel. We are now adding replacing the two units with (1) unit that is more sensitive to voltage drops and is having issues with errors and shutdowns. The original branch conductors are not sized to provide less than 5% total voltage drop recommended by NEC although the equipment manufacturer allows up to +-10%.

Is it allowable to use join the two separate branch conduits to feed (1) piece of equipment using (1) OCPD to reduce the voltage drop?
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What size are the conductors?
 
You cannot parallel conductors that small. What current does the single HVAC unit require?

You can fit three #1-0 conductors in 1.25" EMT with no EGC, or three #1s in 1.25" PVC with one.
 
textmi said:
The conductors are 3#4,1#6 ground in a 1 1/4 conduit (each). They would be used to serve a 208, 3ph load.
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With that size raceways your choices are limited. As Larry stated you'll need to use #1/0 in each raceway to parallel them. You could always use smaller conductors for the last few feet to connect to the unit.
 
LarryFine said:
I was actually suggesting that a single conduit may suffice.
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Could be but the OP hasn't provided a calculation. I meant to say that your post mentioned that 3-#1/0 would fit in an 1.25" EMT which is the minimum size threshold for parallel conductors.
 
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