Use this eight-step process to calculate the weight of braid or spiral shields based on your desired amount of shielding coverage. Keep the following guidelines in mind:

- Recommended for the angle of shield to cable axis is 20 to 40º when diameters under shield (D) is 0.020-inches to 0.380-in, and 40 to 80º for D values greater than 0.380-in.
- Rounded number of strands (N) is typically an integer value between 1 and 13.

**Step 1.**

**Convert desired coverage (%) into coverage factor (F).**

**Braid Shield**

\[F = 1 - \sqrt {\frac{{100 - \% }}{{100}}} \]

**Spiral Shield**

\[F = \frac{\% }{{100}}\]

**Step 2.**

**Select angle of shield to cable in degrees (a) and calculate number of strands (N)**

**Braid Shield**

\[N = \frac{{2\pi \cos (a)(D + 2d)F}}{{dC}}\]

**Spiral Shield**

\[N = \frac{{\pi \cos (a)(D + d)F}}{{dC}}\]

**Step 3.**

**Round number of strands (N) and recalculate angle (a)**

**Braid Shield**

\[a = {\cos ^{.1}}\left( {\frac{{CNd}}{{2\pi (D + 2d)F}}} \right)\]

**Spiral Shield**

\[a = {\cos ^{.1}}\left({\frac{{CNd}}{{\pi (D + d)F}}} \right)\]

**Step 4.**

**Using new angle from Step 3, calculate picks per inch (P)**

**Braid Shield**

\[P = \left( {\frac{{C\tan (a)}}{{2\pi (D + 2d}}}\right)\]

**Spiral Shield**

\[P = \frac{{C\tan (a)}}{{\pi (D + d)}}\]

**Step 5.**

**Round up picks per inch (P) to next increment, and recalculate angle (a).**

**Braid Shield**

\[a = {\tan ^{.1}}\left({\frac{{2\pi P(D + 2d)}}{C}} \right)\]

**Spiral Shield**

\[a = {\tan ^{.1}}\left({\frac{{\pi P(D + d)}}{C}} \right)\]

**Step 6.**

**Recalculate coverage factor (F)**

**Braid Shield**

\[F = \frac{{NPd}}{{\sin(a)}}\]

**Spiral Shield**

\[F = \frac{{NPd}}{{\sin(a)}}\]

**Step 7.**

**Recalculate coverage (%)**

**Braid Shield**

\[\% = 100(2F - {F^2})\]

**Spiral Shield**

\[\% = 100F\]

**Step 8.**

**Calculate weight of shield in pounds per thousand feet (W).**

**Braid Shield**

\[W = \frac{{1.03CNw}}{{\cos (a)}}\]

**Spiral Shield**

\[W = \frac{{1.03CNw}}{{\cos (a)}}\]