C27 License - C-27 Landscaping Contractor License Drainage and Lighting Systems Questions and Answers — Questions and Answers
Question 1: When installing a French drain system to manage subsurface water, what is the generally accepted minimum slope or grade required for the pipe to ensure proper water flow by gravity?
- 0.5% (1/16 inch drop per 10 feet)
- 1% (1 inch drop per 8-10 feet) (Correct answer)
- 3% (3.5 inch drop per 10 feet)
- 5% (6 inch drop per 10 feet)
Correct answer: 1% (1 inch drop per 8-10 feet)
A French drain relies on gravity to move water. A generally accepted minimum slope is 1%, which translates to a drop of about 1 inch for every 8 to 10 feet of pipe. This ensures that water flows effectively towards the discharge point and prevents pooling within the drain itself.
Question 2: A client wants to install low-voltage landscape lighting around their new patio. According to the National Electrical Code (NEC), what is the maximum voltage allowed for these types of lighting systems?
- 12 volts
- 24 volts
- 120 volts
- 30 volts (Correct answer)
Correct answer: 30 volts
NEC Article 411 specifically covers lighting systems operating at 30 volts or less. This standard is in place to ensure safety in outdoor, wet, or damp locations where landscape lighting is typically installed.
Question 3: Which of the following drainage solutions is specifically designed to intercept and remove surface water from hardscapes like driveways, patios, and pool decks?
- French Drain
- Dry Well
- Channel Drain (Trench Drain) (Correct answer)
- Swale
Correct answer: Channel Drain (Trench Drain)
Channel drains, also known as trench drains, are surface drainage systems consisting of a channel and a grate. They are installed flush with the surface of hardscapes to effectively collect and carry away sheet flow of water, preventing pooling.
Question 4: In a low-voltage landscape lighting installation, what is the primary purpose of using a multi-tap transformer?
- To power different types of bulbs (LED and halogen) simultaneously
- To compensate for voltage drop over long wire runs (Correct answer)
- To allow for the connection of more than 25 fixtures to a single unit
- To meet Title 24 energy efficiency requirements
Correct answer: To compensate for voltage drop over long wire runs
Voltage drop occurs as electricity travels along a wire, resulting in dimmer lights at the end of a long run. A multi-tap transformer has several connection terminals with slightly different voltage outputs (e.g., 12V, 13V, 14V, 15V). By connecting longer wire runs to higher voltage taps, contractors can ensure that all fixtures on the circuit receive adequate voltage and maintain consistent brightness.
Question 5: A landscaping project requires grading the soil adjacent to a new home's foundation to ensure proper surface drainage. According to the California Residential Code (CRC), what is the minimum required fall away from the foundation?
- 2 inches within the first 5 feet
- 4 inches within the first 10 feet
- 6 inches within the first 10 feet (Correct answer)
- 1 foot within the first 20 feet
Correct answer: 6 inches within the first 10 feet
Section R401.3 of the California Residential Code (CRC) mandates that lots shall be graded to drain surface water away from foundation walls. The code specifies that the grade must fall a minimum of 6 inches within the first 10 feet away from the structure to prevent water intrusion.
Question 6: When installing a perforated pipe for a French drain, what is the correct orientation for the drainage holes?
- Facing upward, to allow water to enter from the top.
- Alternating up and down, to catch water from all angles.
- Facing downward, to allow collected water to exit and be carried away. (Correct answer)
- To the side, to prevent clogging from surface debris.
Correct answer: Facing downward, to allow collected water to exit and be carried away.
The perforations or holes in a French drain pipe should be oriented facing downward. The purpose of the system is to collect water that rises from the saturated ground into the gravel-filled trench. The pipe, sitting at the bottom, then acts as a conduit to carry this collected water away. If the holes were on top, the pipe would have to fill completely before it started draining.
C27 License - C-27 Landscaping Contractor License Drainage and Lighting Systems Questions and Answers
When installing a French drain system to manage subsurface water, what is the generally accepted minimum slope or grade required for the pipe to ensure proper water flow by gravity?