You're right to question the necessity of a photocell in addition to a programmable time clock. Here's a breakdown of why you might not need it and what to consider

Reasons Why a Photocell Might Be Redundant:
Programmable Time Clock Functionality

Modern digital time clocks are highly programmable. You can set specific on/off times for different days of the week, adjust for seasonal changes, and even create custom schedules. This allows you to approximate sunrise and sunset times without a photocell.

Fine-Grained Control

A time clock allows you to set specific "on" and "off" times down to the minute. You can tailor the lighting schedule more precisely than a simple photocell on/off trigger.

However, Consider These Points Before Eliminating the Photocell



Submittal Requirements



The most important factor is the submittal's requirements. If the submittal explicitly calls for a photosensor (photocell), you're likely obligated to install it, regardless of whether you think it's necessary. Deviating from the approved submittal can lead to rejection by the inspector or the client. Accuracy and Real-Time Adjustment

A photocell offers real-time, automatic adjustment to changes in ambient light. Overcast days, storms, or even variations in the position of the sun throughout the year can affect the actual need for artificial light. A time clock, even with adjustments, can't account for these moment-to-moment variations.

Client Preference

The surgery center might have a specific reason for wanting a photocell. Perhaps they've had issues with time clock-only systems in the past, or they simply prefer the added automation.

Location Considerations

The time clock may not be connected to the internet. If that is the case, the time clock won't automatically adjust the time throughout the year, or account for power outages.

What To Do


Review the Submittal Thoroughly

Double-check the exact wording of the submittal. Does it say "photosensor required," or does it offer an alternative (like "time clock with astronomical timekeeping")?2.

Communicate with the Engineer/Designer

Contact the engineer or designer who approved the submittal. Explain your reasoning and ask if a photocell is truly necessary or if the time clock alone will suffice. Get their approval in writing to deviate from the submittal.3.

Consult with the Client

If the engineer is unsure, speak to the surgery center's representative. They might have a specific operational requirement that dictates the need for a photocell.4.

Consider an "Astronomical Time Clock"

Some advanced time clocks have "astronomical" functionality. These use pre-programmed sunrise/sunset data for your specific geographic location and automatically adjust the on/off times throughout the year. This is a good compromise between a simple time clock and a photocell, but it may not be enough to satisfy the submittal requirements or the client's needs.

In summary: While a programmable time clock can often perform the same basic function as a photocell, the final decision depends on the submittal requirements, client preferences, and the desired level of accuracy and real-time adjustment. Don't assume you can eliminate the photocell without getting explicit approval from the relevant parties. Communication is key! Flag for review