INSTALLATION SUGGESTIONS (PART IV - Precautions During Cable Pulling cont'd.)

B. Cable Grips

When using a cable grip to pull cables, the maximum tension should not exceed the value shown in the following two tables, or the formula used in the table above.

 
† Interlock Armor pulling tension using pulling grips should be limited to the lesser of the value provided above or 50% of value of T_max calculated using “Pulling Eye” formula.

Note 1: The above tensions correspond to three cables in one grip. The stress on the cable conductor should not exceed 16,000 psi (0.013 lbs/cmil) for annealed copper conductors when using a grip.  For stranded ¾ and full hard aluminum conductors the stress should not exceed 14,000 psi (0.011 lbs/cmil) and 10,000 psi (0.008 lbs/cmil) for solid ½ to full hard aluminum conductors. The allowable conductor stress should be based on two cables sharing a load for three single conductor cables in parallel and triplexed configurations.

Note 2: The manufacturer of the cable(s) used should be contacted to determine the mechanical limitations of the cable(s).

Note 3: It is recommended that pulling grips be used during installation of Polymeric Armored Cables, due to their higher sidewall bearing pressure capabilities.

Pulling Grips Maximum Pulling Tension (psi)

Note 4: The maximum pulling tension stress limit for pulling grips on lead sheathed cable with XMPLE/TRXLPE insulation is 16,000 psi of lead sheath area for a single cable as well as one grip on three cables (per AEIC CG5-2005).

Note 5: The maximum pulling tension stress limit for pulling grips on lead sheathed cable with EPR insulation is 8,000 psi of lead sheath area for a single cable as well as one grip on three cable (per AEIC CG5-2005).

Note 6: The maximum pulling tension stress limit for pulling grips on lead sheathed cable with Paper insulation is 1,500 psi of lead sheath area for a single cable as well as one grip on three cables (per IPCEA P-41-412-1958).

Sidewall Bearing Pressure (Static Conditions)

The dynamic radial pressure of cable which is pulled around a bend under pulling tension should be kept as low as possible and not exceed the following values listed in the table. To calculate these values use the following formula:

P_SW = T_e ÷ B_r

Where:

P_SW = Sidewall Bearing Pressure in pounds per foot of bend radius
T_e = Pulling Tension as cable exits the bend (lbs)*
B_r = Bend radius, in feet

*Note: The maximum pulling tension determined by the above formulas must be observed.

Sidewall Bearing Pressure (Dynamic Conditions)

To calculate the minimum bending radii for dynamic conditions, use the following formula:

MBR = (T_e ÷ P_SW) x 12

Where:

MBR = Minimum Bending Radius (in)
Te = Pulling Tension as cable exits the bend (lbs)*
P_SW = Maximum Sidewall Bearing Pressure in pounds per foot of bend radius from following table

*Note: The maximum pulling tension determined by the above formulas must be observed.

Sidewall Bearing Pressure (lbs/ft of bend radius)*

† Value shown corresponds to a single conductor cable pull. Maximum Sidewall Bearing Pressure limits of 750 and 200 lbs. per foot, respectively, are recommended for a three-conductor pull.

* For a pulling eye/pulling grip, the maximum pulling tension must be observed in addition to the maximum sidewall bearing pressure limit.

** These values are based on the cross-sectional area of one lead sheath.

Note 1: It is recommended that the manufacturer of the cable(s) in question be contacted concerning the mechanical limitations of the cable.