Lightning Risk Calculator Tool

Lightning Risk Analysis Program

Protection Level Selection
Expected lightning frequency (Nd), acceptable frequency (Nc) and efficiency (E) are calculated from the building data.

Note: Acceptable lightning frequency (Nc) is calculated with one of two simplified methods. Changing the standard recalculates only Nc, efficiency (E) and the protection level. The Nd calculation and the values you entered stay the same.

NF C 17-102:1995 — Nc = 0.0055 / (C2 × C3 × C4 × C5). Current method, default.
NFPA 780 — Nc = 0.0015 / (C2 × C3 × C4 × C5).

Protection level I–IV thresholds remain the thresholds already used in this calculator. They do not change with the selected standard.

These options represent the simplified Nc methods of the related standards. They do not mean that the calculator as a whole conforms to NFPA 780, NF C 17-102:1995 or IEC 62305 / TS EN 62305.

Calculation Standard

NF C 17-102:1995 Nc = 0.0055 / (C2 × C3 × C4 × C5) Current method, default NFPA 780 Nc = 0.0015 / (C2 × C3 × C4 × C5)

Building Dimensions

Building Length (L) meters

Building Width (W) meters

Building Height (H) meters

Environmental Coefficient (C1)

Environmental Condition of the Building

Structural Coefficient (C2)

Select the value from the table below based on roof and building material:

Roof Type

Structure Type

Roof / Structure	Metal	Tile	Flammable
Metal	0.5	1.0	2.0
Tile	1.0	1.0	2.5
Flammable	2.0	2.5	3.0

Selected C2 Value: -

Building Content Coefficient (C3)

Value and Flammability of Building Content

Human Density Coefficient (C4)

Human Density in the Building

Building Importance in the Area (C5)

Importance Level of the Building

Thunderstorm Days (Nk)

Annual Thunderstorm Days Select according to your region from the Turkey Thunderstorm Map below.

Calculation Results

Calculation Standard

Nc formula used

Effective Equivalent Area (Ae)

m²

Lightning Density (Ng)

strikes/km²/year

Expected Lightning (Nd)

strikes/year

Total Coefficient (C)

C2×C3×C4×C5

Approved Lightning (Nc)

strikes/year

Efficiency (E)

1-(Nc/Nd)

-

Mesh Size

Down Conductor Spacing

Rolling Sphere Radius

Protection Level Reference Table

Efficiency (E)	Protection Level	Mesh Size	Down Spacing	Rolling Sphere Radius = r
E > 0.98	Level I + Additional Measures	5×5 m²	10	20 m
0.95 < E ≤ 0.98	Seviye I (LPL1)	5x5 m²	10	20 m
0.90 < E ≤ 0.95	Seviye II (LPL2)	10x10 m²	10	30 m
0.80 < E ≤ 0.90	Seviye III (LPL3)	15x15 m²	15	45 m
E ≤ 0.80 veya Nd ≤ Nc	Seviye IV (LPL4)	20×20 m²	20	60 m

Note: IF Nd ≤ Nc, PROTECTION IS OPTIONAL.
IF Nd > Nc, PROTECTION IS REQUIRED. In this case; Efficiency, E=1-(Nc/Nd) calculated value determines the PROTECTION LEVEL.

Active Lightning Rod Selection Tables

Active lightning rods provide a wider protection area compared to standard rod lightning conductors. The tables below show the protection radius (Rp) in meters based on building height and protection level.

Piezoelectric Crystal Active Lightning Rod Selection Table

H(m)	ΔT=15μs				ΔT=30μs				ΔT=45μs				ΔT=60μs
H(m)	I	II	III	IV	I	II	III	IV	I	II	III	IV	I	II	III	IV
2	13	15	18	20	19	22	25	28	25	28	32	36	31	35	39	43
4	25	30	36	41	38	44	51	57	51	57	64	72	63	69	78	85
5	32	37	45	51	48	55	63	71	63	71	81	89	79	86	97	107
6	32	38	46	52	48	55	64	72	63	71	81	90	79	87	97	107
8	33	39	47	54	49	56	65	73	64	72	82	91	79	87	98	108
10	34	40	49	56	49	57	66	75	64	72	83	92	79	88	99	109
20	35	44	55	63	50	59	71	81	65	74	86	97	80	89	102	113
30	35	45	58	69	50	60	73	85	65	75	89	101	80	90	104	116
60	35	45	60	75	50	60	75	90	65	75	90	105	80	90	105	120

Electrostatic Active Lightning Rod Selection Table

H(m)	ΔT=30μs				ΔT=45μs				ΔT=60μs
H(m)	I	II	III	IV	I	II	III	IV	I	II	III	IV
2	19	22	25	28	25	28	32	36	31	35	39	43
4	38	44	51	57	51	57	64	72	63	69	78	85
5	48	55	63	71	63	71	81	89	79	86	97	107
6	48	55	64	72	63	71	81	90	79	87	97	107
8	49	56	65	73	64	72	82	91	79	87	98	108
10	49	57	66	75	64	72	83	92	79	88	99	109
20	50	59	71	81	65	74	85	97	80	89	102	113
30	50	60	73	85	65	75	89	101	80	90	104	116
60	50	60	75	90	65	75	90	105	80	90	105	120

Note: Table values show the protection radius (Rp) in meters.
ΔT: Early conductivity time (μs - microsecond)
H: Lightning rod installation height (meters)

FORMULA	VALUES	RESULT
Ae = LxW + 6xH(L+W) + 9πH²	L=-m, W=-m, H=-m	Ae = - m²
Ng = 0.04 x Td^1.25	Td = -	Ng = -
Nd = Ae x Ng x C1 x 10⁻⁶	C1 = -	Nd = -
C = C2 x C3 x C4 x C5	C2=-, C3=-, C4=-, C5=-	C = -
Nc = 0.0055 / (C2 × C3 × C4 × C5)	Calculation standard: NF C 17-102:1995	Nc = -
E = 1 - (Nc / Nd)		E = -

E	Protection Level	Mesh	Down	r
>0.98	I+Ek	5×5	10	20
0.95-0.98	I	5×5	10	20
0.90-0.95	II	10×10	10	30
0.80-0.90	III	15×15	15	45
≤0.80	IV	20×20	20	60

H	ΔT=15μs				ΔT=30μs				ΔT=45μs				ΔT=60μs
H	I	II	III	IV	I	II	III	IV	I	II	III	IV	I	II	III	IV
2	13	15	18	20	19	22	25	28	25	28	32	36	31	35	39	43
4	25	30	36	41	38	44	51	57	51	57	64	72	63	69	78	85
5	32	37	45	51	48	55	63	71	63	71	81	89	79	86	97	107
6	32	38	46	52	48	55	64	72	63	71	81	90	79	87	97	107
8	33	39	47	54	49	56	65	73	64	72	82	91	79	87	98	108
10	34	40	49	56	49	57	66	75	64	72	83	92	79	88	99	109
20	35	44	55	63	50	59	71	81	65	74	86	97	80	89	102	113
30	35	45	58	69	50	60	73	85	65	75	89	101	80	90	104	116
60	35	45	60	75	50	60	75	90	65	75	90	105	80	90	105	120

H	ΔT=30μs				ΔT=45μs				ΔT=60μs
H	I	II	III	IV	I	II	III	IV	I	II	III	IV
2	19	22	25	28	25	28	32	36	31	35	39	43
4	38	44	51	57	51	57	64	72	63	69	78	85
5	48	55	63	71	63	71	81	89	79	86	97	107
6	48	55	64	72	63	71	81	90	79	87	97	107
8	49	56	65	73	64	72	82	91	79	87	98	108
10	49	57	66	75	64	72	83	92	79	88	99	109
20	50	59	71	81	65	74	85	97	80	89	102	113
30	50	60	73	85	65	75	89	101	80	90	104	116
60	50	60	75	90	65	75	90	105	80	90	105	120

H	ΔT=15μs				ΔT=30μs				ΔT=45μs				ΔT=60μs
H	I	II	III	IV	I	II	III	IV	I	II	III	IV	I	II	III	IV
2	13	15	18	20	19	22	25	28	25	28	32	36	31	35	39	43
4	25	30	36	41	38	44	51	57	51	57	64	72	63	69	78	85
5	32	37	45	51	48	55	63	71	63	71	81	89	79	86	97	107
6	32	38	46	52	48	55	64	72	63	71	81	90	79	87	97	107
8	33	39	47	54	49	56	65	73	64	72	82	91	79	87	98	108
10	34	40	49	56	49	57	66	75	64	72	83	92	79	88	99	109
20	35	44	55	63	50	59	71	81	65	74	86	97	80	89	102	113
30	35	45	58	69	50	60	73	85	65	75	89	101	80	90	104	116
60	35	45	60	75	50	60	75	90	65	75	90	105	80	90	105	120

H	ΔT=30μs				ΔT=45μs				ΔT=60μs
H	I	II	III	IV	I	II	III	IV	I	II	III	IV
2	19	22	25	28	25	28	32	36	31	35	39	43
4	38	44	51	57	51	57	64	72	63	69	78	85
5	48	55	63	71	63	71	81	89	79	86	97	107
6	48	55	64	72	63	71	81	90	79	87	97	107
8	49	56	65	73	64	72	82	91	79	87	98	108
10	49	57	66	75	64	72	83	92	79	88	99	109
20	50	59	71	81	65	74	85	97	80	89	102	113
30	50	60	73	85	65	75	89	101	80	90	104	116
60	50	60	75	90	65	75	90	105	80	90	105	120

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Lightning Risk Calculator Tool

Lightning Risk Analysis Program

Calculation Standard

Building Dimensions

Environmental Coefficient (C1)

Structural Coefficient (C2)

Building Content Coefficient (C3)

Human Density Coefficient (C4)

Building Importance in the Area (C5)

Thunderstorm Days (Nk)

Calculation Results

-

Protection Level Reference Table

Active Lightning Rod Selection Tables

Piezoelectric Crystal Active Lightning Rod Selection Table

Electrostatic Active Lightning Rod Selection Table

H	ΔT=15μs				ΔT=30μs				ΔT=45μs				ΔT=60μs
H	I	II	III	IV	I	II	III	IV	I	II	III	IV	I	II	III	IV
2	13	15	18	20	19	22	25	28	25	28	32	36	31	35	39	43
4	25	30	36	41	38	44	51	57	51	57	64	72	63	69	78	85
5	32	37	45	51	48	55	63	71	63	71	81	89	79	86	97	107
6	32	38	46	52	48	55	64	72	63	71	81	90	79	87	97	107
8	33	39	47	54	49	56	65	73	64	72	82	91	79	87	98	108
10	34	40	49	56	49	57	66	75	64	72	83	92	79	88	99	109
20	35	44	55	63	50	59	71	81	65	74	86	97	80	89	102	113
30	35	45	58	69	50	60	73	85	65	75	89	101	80	90	104	116
60	35	45	60	75	50	60	75	90	65	75	90	105	80	90	105	120

H	ΔT=30μs				ΔT=45μs				ΔT=60μs
H	I	II	III	IV	I	II	III	IV	I	II	III	IV
2	19	22	25	28	25	28	32	36	31	35	39	43
4	38	44	51	57	51	57	64	72	63	69	78	85
5	48	55	63	71	63	71	81	89	79	86	97	107
6	48	55	64	72	63	71	81	90	79	87	97	107
8	49	56	65	73	64	72	82	91	79	87	98	108
10	49	57	66	75	64	72	83	92	79	88	99	109
20	50	59	71	81	65	74	85	97	80	89	102	113
30	50	60	73	85	65	75	89	101	80	90	104	116
60	50	60	75	90	65	75	90	105	80	90	105	120