309A Grounding and Bonding 6

Question 1

What is the CEC requirement for grounding electrode conductor material when it passes through a metal enclosure?

Accepted Answer

The enclosure must be bonded to the grounding electrode conductor at both ends

Answer

When a grounding electrode conductor passes through a metal enclosure (such as a steel conduit), the enclosure must be bonded to the conductor at both ends to prevent impedance in the grounding path due to inductive effects.

Question 2

What is the purpose of supplementary bonding in a healthcare facility?

Accepted Answer

To minimize voltage differences between conductive surfaces that a patient might simultaneously contact

Answer

Healthcare facilities require supplementary bonding to limit touch voltage between exposed conductive surfaces to safe levels (typically less than 20 mV), as patients may be more vulnerable to electric shock.

Question 3

According to the CEC, what is the minimum size of the bonding jumper for a 200 A service?

Accepted Answer

No. 2 AWG copper

Answer

CEC Table 16 requires a minimum No. 2 AWG copper main bonding jumper for a 200 A service, matching the grounding electrode conductor size to ensure adequate fault current capacity.

Question 4

What is the effect of a high-resistance ground connection?

Accepted Answer

It may prevent overcurrent devices from operating during a ground fault, creating a shock and fire hazard

Answer

A high-resistance ground connection limits fault current flow, potentially preventing breakers or fuses from tripping during a ground fault. This leaves the fault energized, creating ongoing shock and fire hazards.

Question 5

What is a ground fault indicator used for in a high-resistance grounded system?

Accepted Answer

To alert operators to a ground fault so it can be located and repaired without shutting down

Answer

In high-resistance grounded systems, ground faults are limited to low current levels that don't cause immediate damage. Ground fault indicators alert operators to locate and repair the fault during a planned shutdown.

Red Seal Electrician 309A Practice Test

Red Seal Electrician 309A Practice Test

309A Grounding and Bonding 6