306A Fixture Installation 3

Question 1

What is the minimum size of a trap required for a residential bathtub?

Accepted Answer

1½ inch

Answer

A residential bathtub requires a minimum 1½-inch trap to handle the drainage flow rate from the bathtub without causing excessive backup or slow drainage.

Question 2

When installing a bidet, what backflow prevention device is required?

Accepted Answer

A vacuum breaker on the hot and cold supplies

Answer

A vacuum breaker is required on the bidet's hot and cold water supplies because the spray nozzle can be submerged below the flood level rim, creating a potential cross-connection with the potable water supply.

Question 3

What is the purpose of an 'overflow' on a lavatory basin?

Accepted Answer

To prevent the basin from overflowing if the drain is closed and the faucet is left running

Answer

The overflow opening near the top of the lavatory basin allows water to drain into the waste pipe if the basin is plugged and the faucet is left running, preventing water from spilling onto the floor.

Question 4

What is the correct sequence for roughing in a shower installation?

Accepted Answer

Install the framing, set the drain to the correct height, install the valve body at the correct depth, and connect supply and drainage

Answer

The correct sequence is: frame the shower stall, set the drain at the correct height relative to the finished floor, install the valve body at the correct depth behind the finished wall surface, and connect all supply and drainage piping.

Question 5

What type of trap is required under a kitchen sink with a food waste disposer?

Accepted Answer

P-trap connected to a properly vented drain

Answer

A P-trap connected to a properly vented drain is required under a kitchen sink with a food waste disposer. The disposer does not replace the need for a trap and vent to prevent sewer gas entry.

Red Seal Plumber 306A Practice Test

Red Seal Plumber 306A Practice Test

306A Fixture Installation 3