This article originally appeared in PS 743 (Oct 14), pp. 23-24.
Mechanics, when working on electrical systems always make sure circuit breakers are in the off (pulled position). If they must be locked or deactivated, follow the procedures in para 67 of WP 028 00 in TM 1-1500-323-24-1,
Installation and Repair Practices Aircraft Electrical and Electronic Wiring (Apr 14).
During aircraft ground operations, there are times when positive lockout deactivation of circuit breakers will be required to prevent damage to the aircraft and yourself. Unfortunately, it’s
not happening. And that’s almost always because mechanics say they don’t have the equipment to lock circuit breakers.
Circuit breakers
must have a lockout ring, collar or safety lockout sleeve installed on the circuit breaker anytime you work on electrical systems. If you
don’t have any of these items order them
now.
The TM lists the part numbers for the lockout sleeves and kits you’ll need, but not the NSNs. Here’s a complete list:
Table 1: Safety locks, sleeves and kits NSNs and part numbers
| # |
Item |
NSN |
PN |
| 1 |
Safety lock, small (for 3/8-in circuit breakers) |
5925-01-580-4662 |
296050002-1 |
| 1 |
Safety lock, large (for 7/8-in circuit breakers) |
5925-01-609-6121 |
296050008 |
| 2 |
Safety lock sleeve |
5925-01-609-6208 |
296050009 |
| 3 |
Clip for safety lock and sleeve |
5925-01-609-6211 |
296050018 |
4 |
Safety lock kit (contains10 small safety lock, 2 large safety lock, 12 safety lock sleeves, 12 warning/danger tags and 12 clips) |
5935-01-609-6893 |
296050020-1 |
5 |
Safety lock kit (contains 18 small safety locks, 18 warning/danger tags, and
18 clips |
5935-01-609-6266 |
296050020-2 |
Table 1 legend