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vault backup: 2026-05-07 17:12:50

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Zane Meyers
2026-05-07 17:12:50 -04:00
parent c6e180827b
commit 9b64e7495f
21 changed files with 89 additions and 56 deletions
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nfpa-70_240_overcurrent-protection.md
+7 -7
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@@ -1204,7 +1204,7 @@ Feeder and branch-circuit conductors shall be protected at the point the conduct
For feeder taps specified in 240.21(B)(2), (B)(3), and (B)(4), the tap conductors shall be permitted to be sized in accordance with Table
240.92(B).
Table 240.92(B) Tap Conductor Short-Circuit Current Ratings
##### Table 240.92(B) Tap Conductor Short-Circuit Current Ratings
Tap conductors are considered to be protected under short-circuit conditions when their short-circuit temperature limit is not exceeded.
@@ -1212,15 +1212,15 @@ Conductor heating under short-circuit conditions is determined by (1) or (2):
* (1) _Short-Circuit Formula for Copper Conductors_
$$
(I^2|A^2)t = 0.0297 \log_{10} [(T_{2} + 234)/(T_{1} + 234)]
$$
$$
(I^2|A^2)t = 0.0297 \log_{10} [(T_{2} + 234)/(T_{1} + 234)]
$$
* (2) _Short-Circuit Formula for Aluminum Conductor_
$$
(I^2|A^2)t = 0.0125 \log_{10} [(T_{2} + 228)/(T_{1} + 228)]
$$
$$
(I^2|A^2)t = 0.0125 \log_{10} [(T_{2} + 228)/(T_{1} + 228)]
$$
where: