Conductors in Free Air

[Electric Eel]

When there r more than 4 conductors in free air, what table(s) should v consider?
Is it Table 2 only or
use table 1 / table 5C or
table 2 / table 5C ?

[neil seidner]

Did you check out the rule reference on the top of Table 5B?

Rule 12-2210 is also interesting too, as it deals with Tables 1 and 3 as well Tables 2 and 4 with correction factors from Tables 5A,5C and 5D. Specifically being applied to cable trays

[Electric Eel]

Hi CCrash
Thanx for the reply

The rule reference on the top of Table 5B r for Table 5A and those r with regard to ambient temperature.

The rule reference (2) of Table 5B (below T-5B) is telling to consider the free air conductors as if they r inside a raceway. That is my Q
-----------------------------------------------
When there r more than 4 conductors in free air, what table(s) should v consider to find the ampacity?
Is it Table 2 only or
use table 1 / table 5C or
table 2 / table 5C ?

Thanx for any help

[neil seidner]

The rule reference at the top of 5B makes reference to 4-004(9). It is a little easier to understand than Note #2 at the bottem of 5B.

Look closely at wording of the entire subrule (9). There is no mention of using a correction factor when using Table 2 (or 4) to find ampacity for more than four conductors. Since a correction factor (Table 5B) is mentioned for using Table 1 (or 3) on two to four conductors (in the very same sentence). You can assume that the writer of the rule did not simply forget about correction factors, or that the correction factors are located in another section of the code book.

The reason there is no need to apply a correction factor is that there is more air circulation and more heat dissipation in a free air conductor (when compared to an identical number of conductors in conduit).

[Electric Eel]

Yes, Sir

It seems to be logical to think in the way u suggests.

Regards