ASCO G7ATB / G962 — Main Contact Inspection and Replacement
Maintenance · Main contacts
For the ASCO G7ATB / G962, from the ASCO service manual.
Before you start
- The arc chutes are fragile. To prevent breakage, avoid jarring them and do not use any tool to pry them loose. If they become cracked, replace them.
- To prevent the possibility of personal injury, be sure to pin the weight to the weight frame so that the mechanism cannot move while replacing the contact assemblies.
Procedure
- Bypass, isolate, and pull out the transfer switch and verify that no electrical power is present.
- Use the maintenance handle to open the contacts that will be replaced (if not already open).
- Remove the interphase barriers (one per pole): loosen two round-head screws and slide the barrier away until the keyholes clear the screws.
- Carefully remove the arc chutes: use a 5/8 in nutdriver to remove two long insulator nuts, then pull the arc chute outward off the long threaded rods.
- Pin the weight to the frame with the adjusting pin: use hole 2 for upper contacts and hole 6 for lower contacts.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Source: ASCO service manual. Steps and values are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.