Master Electrician Exam (NEC)Grounding and BondingMedium
A master electrician is installing a new 200A, 120/240V, single-phase service for a residential dwelling. The service entrance conduit is 2-inch rigid metal conduit (RMC) and the service conductors are 3/0 AWG copper. What is the minimum size copper bonding jumper required to bond the service raceway to the service enclosure?
- ANo. 8 AWG
- BNo. 2 AWG
- CNo. 4 AWG
- DNo. 6 AWG
Show answer & explanationAnswer & explanation
Correct answer: D. No. 6 AWG
According to NEC 250.102(C)(1) and Table 250.102(C)(1), the bonding jumper for a service raceway is sized based on the size of the ungrounded service-entrance conductors. For 3/0 AWG copper service conductors, the minimum size copper bonding jumper required is No. 6 AWG.
Why the other options are wrong
- A. This size is too small for 3/0 AWG service conductors.
- B. This size is significantly larger than required for 3/0 AWG service conductors.
- C. This size is larger than required for 3/0 AWG service conductors.
Service Raceway Bonding Jumper Sizing
The bonding jumper for a service raceway must be sized according to NEC Table 250.102(C)(1) based on the size of the ungrounded service-entrance conductors.
- Sized per Table 250.102(C)(1).
- Based on ungrounded service-entrance conductor size.
- Ensures reliable path for fault current.
Memory trick: Bonding jumpers connect, sizing must be perfect.