electric iron is plugged into a receptacle of 110v,voltage loss from panel to receptacle is 6v,voltage line is

Question

A. 104v
B. 110v
C. 116v
D. 120v

A single #10 copper wire with type THW insulation thats used in free air with an ambient temp. of 158 F has an ampacity of.

A. 16.5a
B. 31.9a
C. 36.9a
D. 40.0a


Five #8 aluminum conductors with THHN insulation are to be routed through a conduit found in a boiler room with an ambient temp. of 75C. The ampacity of each conductor is.

A. 14.8a
B. 17.0a
C. 36.6a
D. 48.0a

Answer 1

Hi, I started to answer this question and I realized that my 1983 NEC information is outdated, because I can't come up with any of the correct numbers on the list for questions 2 and 3.

The answer to 1. would be C 116V That one is obvious.

To get the answers to 2 and 3, you need to get a copy of the latest National Electric Code and look up "Allowable Ampacities of Insulated Conductors".

The table will list all the wire gauges on the left, and the wire types along the top (THHN, THW, etc). There will be one table for "free air" and one table for "cables in conduit and raceways".

Get the maximum rating for the wire size and type, and then find the correction factor for that table (at the bottom?) 158 degrees F is 70 degrees C, so according to my old table, the correction factor is 0.41 for THHN I imagine the correction factor will be different in the latest version of the NEC.

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