Eaton Cutler-Hammer, O & M Manual

IB01602002E

Page 22

Effective 10/02

Table 7.1  Periodic Maintenance Procedures

a. Make transfer switch equipment safe for 

Disconnect line power from equipment being serviced by 

inspection and/or maintenance.

opening next highest disconnect device. Make certain that 
any accessory control power is switched off and logic plugs 
disconnected.

b. Inspect structure area for safety hazards or

Inspect area, especially where switching devices are  

potential maintenance problems.

installed, for any safety hazards, including personnel 
safety and fire hazards. Exposure to certain chemical  
vapors can cause deterioration of electrical connections.

Inspect for accumulated dirt, loose hardware or physical 
damage.

Examine primary insulation for evidence of cracking or 
overheating. Overheating will show as discoloration, 
melting, or blistering of conductor insulation, or as pitting 
or melting of conductor surfaces due to arcing.

Inspect secondary control connections for damage, and 
control wiring for insulation integrity.

c. Inspect switching devices for dust, dirt, soot, 

Remove dust, dirt, soot, grease, moisture and corrosion 

grease, moisture or corrosion.

contamination from the surface of the switching device 
using a dry soft lint-free cloth, dry soft bristle brush and 
vacuum cleaner. Do not blow debris into circuit breaker or 
nearby breaker structure. If contamination is found, look for 
the source and fix the problem.

d. Check for material integrity, uneven wear, 

Severe material cracking will require replacement and

discoloration or loose hardware.

loose hardware will need to be tightened.

e. Check terminals and connectors for looseness

Overheating will show as discoloration, melting, or

or signs of overheating.

blistering of conductor insulation.

Connections that do not have signs of looseness or 
overheating should not be disturbed.

f. Exercise the switching devices if they are 

If a switching device is used for frequent switching during 

not often exercised while in operation. This 

normal operation, this step can be disregarded.

will permit wiping action by the contacts. 

g. Inspect NEMA 3R filters for blockage or 

For NEMA 3R enclosed transfer switches with venting, 

contamination

check that air filters are clean and uncompromised.
Replace filters as necessary (Cat. # TSAFFM)

h. Return transfer switch equipment to service.

Make certain all barriers are in place and doors closed.
Re-apply secondary and primary power.

Step

Action