Little help with 2 calculations.

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daiashi

daiashi

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Need help with 2 calculations and code references if you could please.
First one.Equipment terminations provided are 75c and type THHN copper
conductors in conduit are to be used.The service is a 3 phase with 200
amps for each ungrounded conductor.What is the minimum allowable size
of the ungrounded conductors?Second one.A 240v,single phase branch
circuit will supply an electric furnace that has elements rated at 12 kva
and a motor rated at 1.5kva.Equipment terminations provided are 75c
and type THW copper conductors are to be used.What is the minimum
allowable size of the branch-circuit conductors?
Thanks in advance for your help.:smile:
 
daiashi said:
Need help with 2 calculations and code references if you could please.
First one.Equipment terminations provided are 75c and type THHN copper
conductors in conduit are to be used.The service is a 3 phase with 200
amps for each ungrounded conductor.What is the minimum allowable size
of the ungrounded conductors?QUOTE]



Residential service or other?? Is the THHW outside??

daiashi said:
A 240v,single phase branch
circuit will supply an electric furnace that has elements rated at 12 kva
and a motor rated at 1.5kva.Equipment terminations provided are 75c
and type THW copper conductors are to be used.What is the minimum
allowable size of the branch-circuit conductors?
Thanks in advance for your help.:smile:
Click to expand...

424.3 Branch Circuits.
(B) Branch-Circuit Sizing. The ampacity of the branch-circuit conductors and the rating or setting of overcurrent protective devices supplying fixed electric space-heating equipment consisting of resistance elements with or without a motor shall not be less than 125 percent of the total load of the motors and the heaters.
Click to expand...
 
daiashi said:
Need help with 2 calculations and code references if you could please.
First one.Equipment terminations provided are 75c and type THHN copper
conductors in conduit are to be used.The service is a 3 phase with 200
amps for each ungrounded conductor.What is the minimum allowable size
of the ungrounded conductors?
Thanks in advance for your help.:smile:
Click to expand...

You need to use table 310.15 for your wire size and annex C for the conduit size. The ampere of the wire is based upon the calculated load.(Table 310.15(B)6 is for single phase 3-wire services.)
Rick
 
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