Forgive me, this post deviates from the normal electrical side of my job! While I was working as an operator, I was asked to assist in the mechanical drainage sump maintenance.

The drainage sump is where water runoff from inside the plant ends up. An oil skimmer constantly runs to pick up any trace amounts of oil in the water before it is pumped out into the tailrace.

Every year, the mechanics pump the water out of the drainage sump until a catwalk is visible. They clean the sump pit and the filters.

As the operator, it was my job to ensure proper valve positions. The valves that drain the trenches into the drainage sump needed to be closed. I had to keep an eye on the trenches to ensure they didn’t overflow. If they did, it would be my responsibility to open the valves again.

Pictured below is one of the trenches that I monitored.

It’s a long way down and it is slippery. A fall arrest and retrieval system are necessary. The mechanics also had to work under a confined space permit. Here is the mechanical trainee descending the ladder.

Part of the confined space permit is to have at least one safety monitor at all times. Here are the two mechanical technicians monitoring the  mechanical trainee above.

This is the tool used to open and close the trench drain valves.

This was an installation that required the teamwork of both the mechanical and electrical crews.

The electrical part of the job included wiring the sail switch, humidistat and solenoid valve for water flow.

Basic electrical operation of a humidifier

The humidifier circuit operates only when the furnace is running. The humidistat calls for moisture to be added to the air. The sail switch detects airflow and the solenoid (electrically operated valve) opens allowing water to flow through the wicking filters. The moisture passes through the ducting and throughout the house.

The humidistat and the sail are two points at which the electrical circuit can be broken. Both switches must be closed for the solenoid valve to become energized. If the sail switch doesn’t detect air flow, or if the humidistat is satisfied with the amount of moisture in the air, the circuit will not be complete and water will not flow.

The humidistat looks like a thermostat. The difference is the dial points to various percentages of humidity rather than temperatures. It is installed inside the duct where air can pass over it.

The installation was a success and the humidifier passed all of its operational tests.

Whenever we require an extension cord to be used outside for a piece of equipment, the receptacle must be GFCI (ground fault circuit interrupter) protected. Often we use extension cords that have a special GFCI incorporated into the male end of the cord. Pictured below is the male end of the cord. The two buttons are “test” and “reset”.

While we were working on a breaker in the switchyard, we encountered some rain. We discovered that the seal that deems this cord weatherproof had been compromised, and our receptacle box had filled with water. It was removed from service and I was given the task of repairing the unit.

The first challenge was to remove the cover. The screws had been stripped, so once I managed to remove them, I needed to re-tap all of the holes. To ensure the covers would be flush with the box, I used countersunk screws.

The next step was to replace both receptacles. I found that the original receptacles had been terminated incorrectly. I terminated the new receptacles the correct way.

(Above: Incorrect - I was taught to always terminate wires on the terminal screws, never to push the wire through the back.)

(Above: Correct - using the terminal screws on the side of the receptacle)

I put everything back together and tested the GFCI. It worked! The cord was returned to service. Here’s a view of the final product: