FREE IEC Basic Electrical Standards Questions and Answers
What color is an electrical grounding conductor permitted to be?
Explanation:
An electrical grounding conductor is permitted to be green in color according to electrical code standards. The green color signifies that the conductor is intended for grounding purposes, helping to ensure proper identification and safety in electrical installations.
What is the minimum wire size needed to limit the voltage drop to 5% when running a 300 ft length of type NM-B cable to supply power to a 120 volt, 1/2 HP 8-amp load?
Explanation:
To limit the voltage drop to 5% for a 300 ft run of NM-B cable to a 120-volt, 1/2 HP 8-amp load, a minimum wire size of 10 AWG is needed. This gauge ensures that the voltage drop over the distance of the cable remains within acceptable limits, maintaining proper voltage supply to the load.
What is the maximum amp rating for a circuit breaker that can be installed on a 12 AWG copper circuit conductor connected to multiple receptacles?
Explanation:
A 20-amp circuit breaker is the largest that can be installed on a 12 AWG copper circuit conductor. This is in accordance with the National Electrical Code (NEC) regulations for circuit protection, ensuring that the circuit is adequately protected from overcurrent conditions while using 12 AWG copper conductors.
After six 12 AWG wires are previously installed in a 4 11/16 x 2 1.8 square box, how many number 10 AWG conductors may be installed?
Explanation:
The box fill calculation involves counting each conductor and device in the box, where each conductor has a specific fill volume based on its size. For example, a 10 AWG conductor typically occupies more space than a 12 AWG conductor. In this scenario, with six 12 AWG conductors already present, you can add up to 11 number 10 AWG conductors while complying with box fill requirements.
What is the minimum depth requirement for installing underground feeder cable in PVC conduit under a building?
Explanation:
Underground feeder cable in PVC under a building must be installed at least 0 inches deep. The cable is typically installed in a PVC conduit, which provides mechanical protection. However, local codes may vary, so it's essential to consult with local regulations to ensure compliance.
What type of switch will be used to break two underground circuit conductors such as to a motor?
Explanation:
A double-pole switch is used to simultaneously disconnect both the hot and neutral conductors of a circuit. This ensures complete isolation of the circuit, making it safe to work on electrical equipment like motors.
What is the minimum amp rating for the service disconnect of a single-family dwelling with a computed load of 10 KVA?
Explanation:
For a single-family dwelling with a computed load of 10 KVA, the minimum size service disconnect is 100 amps. This is based on typical residential service requirements and is sufficient to handle the expected electrical demand of the dwelling.
How should two identical 24-volt loads be connected to a single 24-volt battery to ensure they receive the correct voltage?
Explanation:
To ensure that each load receives the correct voltage from the 24-volt battery, the loads should be connected in parallel. In a parallel connection, each load has its path to the battery, allowing it to operate independently and receive the full voltage provided by the battery.
In a dwelling, at least how many ampere branch circuit must be provided for bathroom receptacles?
Explanation:
According to the National Electrical Code (NEC), a minimum of a 20-ampere branch circuit must be provided for bathroom receptacles in a dwelling. This circuit is dedicated to powering the outlets in the bathroom and is required to meet the electrical demands of modern bathroom appliances and devices.
Under what location classification would a luminaire installed under a covered breezeway need to be marked as suitable for?
Explanation:
A luminaire installed under a covered breezeway would need to be marked as suitable for a ""damp"" location. Even though it's covered, it can still be exposed to moisture from humidity or occasional splashing, so the fixture needs to be designed to withstand these conditions safely.
What type of condition occurs if the hot conductors are inadvertently touched together in a junction box within a circuit installed in EMT between a 2-pole circuit breaker and a load?
Explanation:
If the hot conductors are touched together in a junction box somewhere in the conduit run, it creates a short circuit condition. This means that the current flows through an unintended path with minimal resistance, potentially leading to excessive current flow, overheating, and electrical hazards.