diff --git a/phosphor-power-supply/power_supply.hpp b/phosphor-power-supply/power_supply.hpp
index ec58bf3..2c61f13 100644
--- a/phosphor-power-supply/power_supply.hpp
+++ b/phosphor-power-supply/power_supply.hpp
@@ -45,6 +45,9 @@
 constexpr auto LOG_LIMIT = 3;
 constexpr auto DEGLITCH_LIMIT = 3;
 constexpr auto PGOOD_DEGLITCH_LIMIT = 5;
+// Number of polls to remember that an AC fault occured. Should remain greater
+// than PGOOD_DEGLITCH_LIMIT.
+constexpr auto AC_FAULT_LIMIT = 6;
 
 /**
  * @class PowerSupply
@@ -380,6 +383,15 @@
     }
 
     /**
+     * @brief Returns true if an AC fault has occurred in the window of
+     * interest.
+     */
+    bool hasACFault() const
+    {
+        return acFault != 0;
+    }
+
+    /**
      * @brief Returns the device path
      *
      * This can be used for error call outs.
@@ -685,6 +697,13 @@
     size_t psCS12VFault = 0;
 
     /**
+     * @brief Set to AC_FAULT_LIMIT when AC fault is detected, decremented when
+     * AC fault has cleared. Effectively forms a timer since last AC failure.
+     * Zero indicates being outside the window of concern.
+     */
+    size_t acFault = 0;
+
+    /**
      * @brief Count of the number of read failures.
      */
     size_t readFail = 0;