Low pressure switches used in either refrigeration or air conditioning systems provide which of the following functions?

Suspended type unit heaters shall have a clearance from combustible materials of at least 18 inches at the sides and 12 inches at the bottom. How much clearance is required at the top if it has a vertical draft hood installed?

Outdoor combustion air shall be provided through openings not less than 3 inches. Attics and crawl spaces are an acceptable source of combustion air when they are vented by mechanical means.

Gas vents shall terminate not less than ___ feet above any forced air inlet located within ___ feet

Gas supply connectors shall not exceed ____ feet

The ladder schematic diagram is made up of _____________________.

The coil of the current starting relay is connected in series with:

To reverse the rotation of a three phase motor it is necessary to:

In the above drawing, symbol “B” would be properly described as:

Cutting holes in structural steel shall be