DIY Manual

39 | P a g e 10-543-1 REV A
DIY Manual
3. Reference Figure 6, and
4. #6 AWG wire is correct (Use 15A row, 40’ to 50’).
** NOTE: The 125% multiplication factor is a means to derate the current-carrying capacity of
the wire for safety reasons, as explained below. Either you decrease current by 80%
OR you oversize wire by 125%.
What does this all mean?
1. Let’s assume you have a solar panel with an Isc of 9.2A.
2. The 9.2A rating is determined under standard test conditions. In the real world,
the panel can produce more than 9.2A due to sunlight intensity as affected by
altitude, reflection due to snow or other obstructions, refraction through clouds,
or even the dryness of the air.
3. So, the panel’s Isc is increased by a correction (safety) factor of 125%, just in
case:
i. 9.2A x 125% = 11.5A
4. Next, the wire that will carry this 9.2A – 11.5A of current needs to be able to
handle this amount of current PLUS its own (safety) correction factor of 125%.
This is called the ampacity of the wire.
i. (9.2A x 125%) x 125% = 11.5A x 125% = 14.4A
Figure 6