Annex I Recommended Tightening Torque Tables from UL Standard 486A-B

This informative annex is not a part of the requirements of this NFPA document, but is included for informational purposes only.

In the absence of connector or equipment manufacturer’s recommended torque values, Table I.1, Table I.2, and Table I.3 may be used to correctly tighten screw-type connections for power and lighting circuits*. Control and signal circuits may require different torque values, and the manufacturer should be contacted for guidance.

Table I.1 Tightening Torque for Screws

*For proper termination of conductors, it is very important that field connections be properly tightened. In the absence of manufacturer’s instructions on the equipment, the torque values given in these tables are recommended. Because it is normal for some relaxation to occur in service, checking torque values sometime after installation is not a reliable means of determining the values of torque applied at installation.

Test Conductor Installed in Connector
Tightening Torque, N-m (lbf-in.)
Slotted head No. 10 and larger*
Slot width 1.2 mm (0.047 in.) or less and slot length 6.4 mm (1in.) or lessSlot width over 1.2 mm (0.047 in.) or slot length over 6.4 mm(1in.)
Split-bolt connectors

Other connectors

AWG or kcmil


*For values of slot width or length not corresponding to those specified, select the largest torque value associated with the conductor size. Slot width is the nominal design value. Slot length shall be measured at the bottom of the slot.

Table I.2 Tightening Torque for Slotted Head Screws Smaller Than No. 10 Intended for Use with 8 AWG (8.4 mm2) or Smaller Conductors

Slot Length of Screwa
Tightening Torque, N-m (lbf-in.)
Slot width of screw smaller than 1.2 mm (0.047 in.)bSlot width of screw 1.2 mm (0.047 in.) and largerb
mm in.
Less than 4 Less than 5∕320.79 (7)1.0 (9)
4 5∕320.79 (7)1.4 (12)
4.8 3∕160.79 (7)1.4 (12)
5.5 7∕320.79 (7)1.4 (12)
6.4 1∕41.0 (9)1.4 (12)
7.1 9∕321.7 (15)
Above 7.1 Above 9∕322.3 (20)

aFor slot lengths of intermediate values, select torques pertaining to next shorter slot lengths. Also, see of UL 486A-2003, Wire Connectors and Soldering Lugs for Use with Copper Conductors, for screws with multiple tightening means. Slot length shall be measured at the bottom of the slot.

bSlot width is the nominal design value.

Annex I: Tightening Torque Tables INFORMATIVE ANNEX I

Table I.3 Tightening Torque for Screws with Recessed Allen or Square Drives

Socket Width Across Flatsa
Tightening Torque, N-m (lbf-in.)
mm in.
3.2 1∕85.1(45)
4.0 5∕3211.3(100)
4.8 3∕1613.5(120)
5.5 7∕3216.9(150)
6.4 1∕422.5(200)
7.9 5∕1631.1(275)
9.5 3∕842.4(375)
12.7 1∕256.5(500)
14.3 9∕1667.8(600)

aSee of UL 486A-2003, Wire Connectors and Soldering Lugs for Use with Copper Conductors, for screws with multiple tightening means.

With the permission of Underwriters Laboratories Inc., material is reproduced from UL 486A-486B-2013, Wire Connectors, which is copyrighted by Underwriters Laboratories Inc., Northbrook, Illinois. While use of this material has been authorized, UL shall not be responsible for the manner in which the information is presented, nor for any interpretations thereof. For more information on UL, or to purchase standards, please visit their website at or call 1-888-853-3503.