Cable Size Calculation for 170 Amp Circuit with Teck90 Cable

What size of 3 conductor aluminum teck90 cable is required for a 170 amp circuit if the breaker has a temperature rating of 90 degrees?

Choose the correct option:

A. 4/0 gauge

B. 2/0 gauge

C. 1/0 gauge

D. 3/0 gauge

Answer:

The required size of a 3 conductor aluminum teck90 cable for a 170 amp circuit with a 90 degrees temperature rated breaker is typically 4/0 (or 0000) gauge, rated for 180 amps.

Explanation:

In order to determine the proper size of a 3 conductor aluminum teck90 cable for a 170 amp circuit with a breaker having a temperature rating of 90 degrees, we would typically refer to the National Electrical Code (NEC) tables. However, as a general guide, one might use 4/0 (or 0000) aluminum wire, which has an ampacity of 180 amps at the 90°C temperature rating. This rating is sufficient to handle a 170 amp load.

It's important to consider that the conductor size could be subject to changes based on various factors, such as the length of the circuit, the voltage drop, and the ambient temperature where the cable will be installed. Also, the frequency and duration of the maximum load should be factored in. Continual loads (lasting more than three hours at a time) should not exceed 80% of the conductor's rated ampacity. Thus, for a 170 Amp circuit, the cable should ideally support at least 212.5 Amps (170A / 0.8).