Dakota Bonding Sizing Guide for Red Seal Exam (CEC 2024)

Types of Bonding Conductors

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There are several bonding conductors in the CEC:

• Bonding Conductor: Connects non-current-carrying metal parts to the grounding system.
• Bonding Jumper: Connects sections of metal enclosures.
• System Bonding Jumper: Connects the grounded conductor (neutral) to the equipment grounding/bonding system.

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Bonding Conductors vs. Bonding Jumpers

(Both are part of the bonding system — but they serve different roles.)

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1. Bonding Conductor

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What it is:
The main wire that connects non-current-carrying metal parts (like enclosures, raceways, pipes, etc.) to the grounding system.

Think of it as:
The main safety highway that connects metal parts to earth ground or to the main grounding point.

Example:
A #6 copper wire running from your metal panelboard enclosure to the ground bus — that’s a bonding conductor.

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2. Bonding Jumper

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What it is:
A shorter bonding wire that connects two metal parts together so they are electrically continuous.

Think of it as:
A bridge between two pieces of metal that might otherwise be electrically isolated.

Types:

• Main Bonding Jumper: Connects the neutral (grounded conductor) to the bonding system (usually in the main service panel)
• Equipment Bonding Jumper: Connects enclosures, conduits, or devices together (like across conduit fittings or motor frames)
• System Bonding Jumper: Connects the neutral to bonding system in separately derived systems (like transformers)

CEC Rules: 10-604 (system jumper), 10-614 (equipment jumper)

Example:
A short wire bonding the two ends of a flexible conduit where continuity might otherwise be lost — that’s a bonding jumper.

**Sizing Bonding JUMPERS and CONDUCTORS is the same**

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How to Size Bonding Conductors (CEC) for Service Equipment

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Step 1: Identify the Largest Ungrounded Conductor - Rule 10-616(2)

Bonding conductor size is based on the ampacity of the size of the largest ungrounded (live) conductor in the system — this could be a single conductor or the largest in a parallel set.

Example: If the largest conductor feeding your panel is a #3 AWG copper, go to Table(s) 1-4, and find the ampacity--that’s your reference point.

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Step 2: Use CEC Table 16

Once you know the size of the largest ungrounded conductor ampacity, go to CEC Table 16 to find the minimum size of the bonding conductor.

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How to Size Bonding Conductors (CEC) for Anythign Other than Service Equipment

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Step 1: Identify the Over-Current Device Protecting the Conductor/Equipment - Rule 10-616(3)

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The Bonding Conductor cannot be less than the O/C protecting the conductors or Equipment.

OR

IF the largest ungrounded conductor has been UPSIZED due to voltage drop, then you HAVE TO go with that instead of the O/C device.

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Step 2: Use CEC Table 16

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Once you know the size of the Over-Current Device go to CEC Table 16 to find the minimum size of the bonding conductor.

FUN FACT: If you are trying to figure out Bonding for a Relocatable Structure, you use Table 41

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Example #1: 

What is the Bonding Conductor size required for a 30 HP, 600-volt,  3-phase squirrel cage motor with a service factor of 1.15 that is operating under normal circumstances and protected by a NTD fuse?

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Step 1: What is the question asking for?

• This is NOT SERVICE.
• So it depends on if the Conductors feeding the branch circuit were up-sized due to Voltage Drop.
• The question does not specify that it was, so we need to figure out the O/C size.
• Over-current. So we pick out only the information that helps us.

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Step 2: What do we have?

• Motor Info and Non-Time Delay Fuse

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Step 3: What do we need?

• FLA (Table 44) Over-current multiplier (Table 29) Over-Current Size (Table 13)
• 32A * 300%= 96A
• 90A NTD Fuse.

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Table 16: 90A is not an option, so we go UP → 100A

• Copper: #8awg
• Aluminum: #6awg

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Example #2

What size of aluminum bonding conductor is needed for a 30 HP, 600VAC,  3-phase SCIM protected by a NTD fuse and supplied by a #6awg R90(XLPE)?

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Step 1: What is the question asking for?

• This question doesn’t mention any type of Over-Current device, so the supply size is the clue.
• Bonding conductor size BUT……..
• Conductor Size.
• Ask yourself: WHICH CONDUCTOR? WHAT’S THE DUTY?

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Step 2: What do we have?

• Motor Info and Duty Type

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Step 3: What do we need?

• FLA (Table 44) Duty: Continuous
• 32A * 125%= 40A
• Table 2 (75°C): #8awg

Since we calculated a #8awg, but the question says a #6awg…that means it was up-sized due to voltage drop.

• Table 2 tells us that a #6awg (75C) is 65A
• Table 16 says “NOT EXCEEDING”, so we have to go to 100A.
• Aluminum is #6awg.

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