CSLB General Building (B) Trade Practice Test

Preguntas de práctica de ejemplo

Algunas preguntas reales de este banco gratuito, con explicaciones completas. Usa la herramienta de arriba para el banco completo.

1. 1. Drainage, Waste & Vent

   A horizontal 2 in fixture branch is installed at the code minimum slope. Over a developed run of 18 ft, how much total fall does the pipe have?

   • a.1-1/8 in
   • b.2-1/4 in
   • c.4-1/2 in
   • d.9 in

   Respuesta: c

   Explicación: Pipe 2-1/2 in and smaller requires a minimum slope of 1/4 in per ft, so 18 ft x 1/4 in = 4-1/2 in of fall. 1-1/8 in comes from using 1/16 in per ft and 2-1/4 in from using the 1/8 in per ft rate that applies only to 3 in and larger pipe. 9 in would be 1/2 in per ft, which is double the required minimum.

   Fuente: IPC §704.1

2. 2. Drainage, Waste & Vent

   Which fitting is required to change direction from horizontal to horizontal in a drainage line?

   • a.A short sweep quarter bend
   • b.A sanitary tee
   • c.A combination wye and 1/8 bend
   • d.A vent tee

   Respuesta: c

   Explicación: A horizontal-to-horizontal change of direction must use a long sweep pattern such as a combination wye and 1/8 bend, which keeps the flow moving without a sharp shoulder where solids collect. A short sweep quarter bend turns too abruptly for horizontal flow, a sanitary tee is only for horizontal-to-vertical, and a vent tee is a dry vent fitting not rated for drainage flow.

3. 3. Drainage, Waste & Vent

   A 3 in horizontal branch must gain 4-1/2 in of fall between two fixed points. At the minimum slope for 3 in pipe, what is the longest run that produces exactly that fall?

   • a.18 ft
   • b.24 ft
   • c.36 ft
   • d.54 ft

   Respuesta: c

   Explicación: At 1/8 in per ft, a run of 36 ft yields 36 x 1/8 = 4-1/2 in of fall. The 18 ft answer uses 1/4 in per ft, which is the slope for 2-1/2 in and smaller pipe, and 54 ft and 24 ft do not produce 4-1/2 in at any code slope for 3 in pipe.

4. 4. Water Supply & Distribution

   A gauge on the building side of the meter shows a static street pressure of 96 psi with no flow. What does the plumbing code require?

   • a.An approved pressure-reducing valve limiting downstream pressure to not more than 80 psi
   • b.Nothing, because the pressure is still under 100 psi
   • c.An increase of one pipe size on the water service
   • d.An approved vacuum relief valve on the water service

   Respuesta: a

   Explicación: Where static pressure exceeds 80 psi, an approved pressure-reducing valve must be installed to hold the downstream distribution system at 80 psi or less. The 100 psi threshold does not exist in the code; 80 psi is the trigger. Upsizing pipe lowers friction loss but does nothing to static pressure, and a vacuum relief valve protects against collapse or siphoning, not high pressure.

   Fuente: UPC §608.2

5. 5. Water Supply & Distribution

   What is the maximum lead content permitted in solder and flux used on a potable water piping system?

   • a.0.2 percent
   • b.0.25 percent
   • c.2 percent
   • d.8 percent

   Respuesta: a

   Explicación: Solder and flux used in potable water piping may not exceed 0.2 percent lead, which is why 50/50 tin-lead solder is prohibited. The 0.25 percent figure is a different limit, the weighted average lead content allowed on the wetted surfaces of pipe, fittings, and fixtures. The 2 percent and 8 percent values are far above any lead-free standard and describe legacy alloys no longer permitted.

   Fuente: UPC §604.0

6. 6. Fixtures & Water Heaters

   A water closet is being roughed in against a side partition in a narrow alcove. Measuring from the finished face of the partition to the center of the closet outlet, what is the minimum dimension the model plumbing codes require?

   • a.12 inches
   • b.14 inches
   • c.15 inches
   • d.18 inches

   Respuesta: c

   Explicación: The centerline of a water closet must be at least 15 inches from any side wall, partition, or vanity, which is what makes a 30 inch wide alcove the practical minimum for a single fixture. The 12 inch figure is the standard rough-in distance from the finished back wall to the closet flange center, not a side clearance. 14 inches and 18 inches are not code minimums; 18 inches is a common designer's comfort dimension and 14 inches is simply short of the requirement.

   Fuente: IPC §405.3.1

7. 7. Fixtures & Water Heaters

   Where an enclosure takes combustion air from an adjacent room through two permanent openings, where must those openings be located?

   • a.Both within 12 inches of the ceiling of the enclosure
   • b.Both within 12 inches of the floor of the enclosure
   • c.One at the ceiling and one at any convenient height on an outside wall
   • d.One within 12 inches of the top of the enclosure and one within 12 inches of the bottom

   Respuesta: d

   Explicación: The two-opening method requires one opening within 12 inches of the top and one within 12 inches of the bottom of the enclosure so that heated air can exhaust high while replacement air enters low. Placing both openings high or both low defeats the convective loop that drives the air exchange. Locating the lower opening at any convenient height does not satisfy the 12 inch dimension.

8. 8. Gas Piping

   A house is served with natural gas having a heating value of about 1,000 Btu per cubic foot. The connected appliances are a 100,000 Btu/h furnace, a 40,000 Btu/h water heater and a 35,000 Btu/h clothes dryer. What total flow, in cubic feet per hour, must the piping downstream of the meter carry?

   • a.132 cfh
   • b.175 cfh
   • c.70 cfh
   • d.1,750 cfh

   Respuesta: b

   Explicación: Add the loads: 100,000 + 40,000 + 35,000 = 175,000 Btu/h, then divide by the 1,000 Btu per cubic foot heating value to get 175 cfh. 132 cfh is what you get if the dryer is left out or a propane figure is mixed in; 70 cfh comes from dividing by 2,500, which is the propane heating value; 1,750 cfh comes from dividing by 100 instead of 1,000.

   Fuente: IFGC §402.4

9. 9. Gas Piping

   Which material is permitted for a buried gas service line running from an outdoor meter to a detached garage, but is prohibited for the piping inside the garage?

   • a.Polyethylene (PE) pipe
   • b.Schedule 40 black steel pipe
   • c.Corrugated stainless steel tubing
   • d.Type L copper tube

   Respuesta: a

   Explicación: PE pipe is permitted only outside underground and must transition to an approved metallic material before it rises above grade or enters a building, and a tracer wire or other locating means must be buried with it. Black steel, CSST and copper (where the gas is not corrosive) are all approved for aboveground interior piping, so none of them are limited to underground use.

   Fuente: IFGC §403

10. 10. Codes & Safety

    A water distribution system that will operate at 45 psi working pressure is tested with water. The plumber pumps it to 48 psi, and after 15 minutes the gauge reads 46 psi. How should the result be reported?

    • a.Pass, because the test pressure of 48 psi exceeded the 45 psi working pressure of the system
    • b.Fail, because the test must be at the working pressure but not less than 50 psi and must hold for 15 minutes with no drop
    • c.Pass, because a 2 psi drop over 15 minutes is within the allowable tolerance for a supply test
    • d.Fail, because a water supply system may only be tested with compressed air at 100 psi

    Respuesta: b

    Explicación: The supply test is run at the system's working pressure but never less than 50 psi, and it must hold for at least 15 minutes without a loss of pressure, so a 48 psi start that falls to 46 psi fails on both counts. Exceeding the working pressure alone is not enough when the code sets a 50 psi floor. There is no allowable pressure drop; any drop indicates a leak. Air may be permitted as an alternate test medium in some jurisdictions, but it is not the only method and 100 psi is not the required value.

    Fuente: IPC §312.5