Kohler — Millivolt Drop Test Procedure
Testing & diagnosis · power contacts
From a Kohler service manual — check it applies to your exact model before use.
Applies to: Kohler RDT
Before you start
- Hazardous voltage. Only authorized personnel should open the enclosure.
Procedure
- Apply a balanced load of at least 10% of the switch rating.
- Measure voltage on both sources from the source lug to the load lug.
- Use an ammeter to measure current flow through the circuit.
- Calculate contact resistance using R = V / I (V in millivolts, I in amps, R in milliohms).
- Compare calculated resistance to the maximum contact resistance table.
- If significantly higher, disconnect power, check connections and lug torques, repeat test.
- If second measurement is also too high, replace the contactor.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- 100-200 A max contact resistance 0.250 milliohms
- 400 A max contact resistance 0.200 milliohms
Source: Kohler 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.