# ANSI/IEEE main bonding jumper symbol

Canonical URL: https://eloragrid.ai/symbols/ansi-main-bonding-jumper
Publisher: Elora Grid
Updated: 2026-10-28
Lookup label: MBJ
Drawing use: SLD, Schematic
Reference families: IEEE / ANSI

## Symbol convention

Convention: IEEE / ANSI
Form: Main bonding jumper form
Independent illustration in IEEE drafting context; no equivalence of every detailed standard graphic is asserted.

US-practice bonding jumper between the grounded neutral and the equipment grounding system at the service.

## In plain English

### What does ANSI/IEEE main bonding jumper mean?

In North American practice the main bonding jumper connects the grounded conductor, the neutral, to the equipment grounding conductor and enclosure at the service equipment. Its function corresponds to the neutral-to-earth link in TN-C-S systems. Single-line diagrams show it at the service disconnect, and separately derived systems have a corresponding system bonding jumper.

### A simple example

This illustration is an independent explanation and not an IEEE graphic. Only one bond should exist per service or separately derived system. Sizing rules come from the applicable electrical code, and the drawing should state the conductor or strap size.

### What the drawings help you do

Locate the bond at the service or derived system source only. Check for unwanted downstream neutral to ground bonds. A main bonding jumper bonds neutral and ground at the service; an equipment bonding jumper bonds metal parts together.

### This particular reference

US-practice bonding jumper between the grounded neutral and the equipment grounding system at the service. A main bonding jumper bonds neutral and ground at the service; an equipment bonding jumper bonds metal parts together.

### Terms

- Schematic: A drawing showing function and connections rather than physical appearance.

Concept diagram: Identify the device and form → Read the connections and state → Check the equipment reference
A guide to reading this reference. The original symbol illustration and its drawing notes appear below; these boxes are not a wiring diagram.

- [IEEE/ANSI 315-1975: graphic symbols for electrical and electronics diagrams](https://standards.ieee.org/ieee/315/515/)
- [Autodesk IEEE Symbol Preview — Miscellaneous](https://help.autodesk.com/cloudhelp/2021/ENU/AutoCAD-Electrical/files/GUID-34282BFD-7B8E-48F3-A6ED-93ADBDDDFBD3.htm)


## What it represents

In North American practice the main bonding jumper connects the grounded conductor, the neutral, to the equipment grounding conductor and enclosure at the service equipment. Its function corresponds to the neutral-to-earth link in TN-C-S systems. Single-line diagrams show it at the service disconnect, and separately derived systems have a corresponding system bonding jumper.
This illustration is an independent explanation and not an IEEE graphic. Only one bond should exist per service or separately derived system. Sizing rules come from the applicable electrical code, and the drawing should state the conductor or strap size.

## How to read it

- Locate the bond at the service or derived system source only.
- Check for unwanted downstream neutral to ground bonds.

## Information to show or reference

- Show the jumper at the service equipment.
- State jumper size.
- Show system bonding jumpers on separately derived systems.

## Important distinction

A main bonding jumper bonds neutral and ground at the service; an equipment bonding jumper bonds metal parts together.

## Facts

- Convention evidence: IEEE 315 graphic conventions for ground and bonding (standards context only)
- Equivalent concept: Neutral to earth link in TN-C-S practice
- Standards context: IEEE/ANSI 315-1975 covers diagram graphics; IEEE lists this edition as Inactive-Reserved.
- Preview: Original educational illustration; consult the publisher and applicable standard for the exact graphic

## Public references

- [IEEE/ANSI 315-1975: graphic symbols for electrical and electronics diagrams](https://standards.ieee.org/ieee/315/515/) — IEEE Standards Association. Graphic-symbol standards context and official status; not a source of reproduced artwork.
- [Autodesk IEEE Symbol Preview — Miscellaneous](https://help.autodesk.com/cloudhelp/2021/ENU/AutoCAD-Electrical/files/GUID-34282BFD-7B8E-48F3-A6ED-93ADBDDDFBD3.htm) — Autodesk. Public IEEE-oriented earth and bonding forms.

## Graphic scope

Independent original educational concept illustration by Elora Grid. Not a certified standards graphic or manufacturer footprint. Unitless; not to scale. Original artwork licence: https://creativecommons.org/licenses/by/4.0/. Publisher material is linked only.