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_{DJ} is defined by equation L.6.6.1.4 as the equivalent collection area of the adjacent structure which equals 40xL_{L. }However, this is the same methodology in the determination of A_{L}. Seems that the methodology used should be similar to that of A_{D}. Why two different variables with the same formula if they’re the supposed to represent different things? - Refer to equation L.6.6.1.2 for the definition of A
_{M}. Confirm if using the equation for A_{D} (for rectangular and complex structures) with an added 500 meters to the length, height and width would be sufficient to determine this variable (i.e. for rectangular the proposed formula would be A_{D} = (L+500) x (W+500) + 6 x (H+500) x (L + W + 1000) + 9 x pi x (H+500)^{2}. - A
_{I} is defined as the collection area of flashes to ground *near* the service. Refer to equation L.6.6.1.5 and figure L.6.6.1.2. Confirm formula, Length of service (meters) x (4000 – 40), is accurate to determine the area. - Refer to section L.6.6.2.8 in the determination of P
_{Z}. It says “…Where SPDs are not installed, the probability of failure of internal systems due to a flash near the connected service (P_{Z}) can be taken from Table L.6.7.8. Where SPDs are installed, the value of P_{Z} can be taken to be the lower value of P_{C} or P_{Z}.” There is no prior calculation method for the determination of P_{Z}._{ }In the case of an SPD being installed am I to evaluate P_{Z} from the aforementioned table and then choose the lower of P_{C} and P_{Z}? - There are two different formulas for the same variable, L
_{A}. Refer to equation L.6.6.3 and L.6.6.3.1 for these formulas. The risk component R_{A }takes into account this variable but it is not clear which L_{A} should be used. - The variable, P
_{W} appears to be no different than P_{V}. Refer to sections L.6.6.2.6 and L.6.6.2.7 for description. I want to make sure there isn’t something I’m missing. Please confirm if this is the case. - There were many errant table references in NFPA 780, i.e. section L.6.6.2.1 defines the requirements for evaluating P
_{A} and then references table L.6.7.1; which is the table for the service environmental coefficient, C_{E}. The correct table for P_{A} is L.6.7.2.