2.6 Parts Of A Photocontrol

2.6.1 Covers

Most manufacturers of utility grade photocontrols appear to have similar covers, bases and legs. The external appearance is the same but construction and longevity may differ. The photocontrol cover is always plastic and usually colored to meet the ANSI C136.10 standard. Below is a table listing the ANSI color standards.

Brown, black and other colors are becoming popular for decorative fixtures. A major Wisconsin utility uses all Brown controls to match their American Electric "shoe box" fixtures. Alabama Power uses brown to differentiate special high temperature controls. Commonwealth Edison, Southern California Edison and Florida Power use black to designate long life electronic controls. Black is also used where the best UV resistance is required.

The cover should be impact resistant; stable to the effects of sunlight, water, salt spray and bird droppings; and provide a good grip for the lineman. The major manufacturers use polypropylene which, when properly compounded, meet the mentioned requirements. In your specifications, you should specify a housing with at least 1 foot-pound of impact resistance. This requirement is not in ANSI C136.10-1996.

CAUTION #1: Some manufacturers use covers that snap-on to the base. These covers may snap off or twist off during control removal or installation. Controls that use screws to hold the cover to base are more rugged.

CAUTION #2: Covers must be opaque. Even a small amount of light transmittance will keep the control from turning ON when the window is covered during testing in full sunlight.

2.6.2 Bases, Legs and Gasket

The photocontrol base supports the current carrying internal members and holds the legs in proper alignment. The photocontrol base is often the first component damaged by excessive heat from the luminaries. Find more discussion in section 3.8, "High Temperature Floodlight Controls."

Gaskets are usually made from polyethylene although the more expensive materials like neoprene are better at staying flexible when there is high heat and humidity. Mid-2001, DTL changed all gaskets to high temperature material tested to 125°C.

Legs should be specified as brass. This is an item that ANSI should require but, at the present time, does not require.