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Grounding Rules NEC 250.24

Grounding Rules NEC 250.24

Grounding Rules NEC 250.24

NEC 250.24 is all about one super important moment in an electrical system:

Where the neutral gets connected to ground — and where it does NOT.

This rule is mostly about service equipment (your first main disconnect / main service panel).

👉 If you want the big picture first, read our NEC Overview: What It Is and Why It Matters.
👉 If you want the simple basics, read our Grounding and Bonding Overview.

 

 

What NEC 250.24 Covers

NEC 250.24 explains how to connect the electrical system to the earth at the service, including:

  • Where the neutral (grounded conductor) is bonded

  • Where the grounding electrode conductor (GEC) connects

  • How to run the grounding and bonding at the service correctly

  • Why you do NOT bond neutral and ground again downstream

 

 

The Simple Idea

At the MAIN service:

✅ Neutral and ground are bonded together ONE time.
This is done using the main bonding jumper in the service equipment.

After that (downstream panels):

❌ Neutral and ground must be kept separate.
No second bond. No “extra connection.” No shortcuts.

 

 

Why This Rule Matters

If neutral and ground get bonded again in a subpanel, bad things can happen:

  • Metal conduit, boxes, and equipment can carry return current (not good)

  • You can get “tingles” or shocks touching metal parts

  • It can cause weird electrical problems and nuisance tripping

  • It makes faults harder to clear properly

  • Inspectors will fail it

NEC 250.24 is there to stop those problems.

 

 

Key Parts You’ll Hear About

Here are the “players” involved in NEC 250.24:

  • Service Disconnect / Service Equipment
    The first main shutoff for the building.

  • Grounded Conductor (Neutral)
    The normal return path for current.

  • Equipment Grounding Conductors (EGCs)
    The green/bare wires or metal paths that carry fault current.

  • Grounding Electrode Conductor (GEC)
    The wire that connects to the ground rod / Ufer / building steel.

  • Main Bonding Jumper
    The link that bonds neutral to the service enclosure at the main service.

 

 

What “Bonded at the Service” Looks Like

At the main service panel, you’ll usually see:

  • Neutral bus bonded to the panel can

  • Bonding screw or bonding strap installed

  • Grounding electrode conductor connected to the neutral bar or a listed location

That is your one neutral-to-ground bond point.

 

 

What NOT to Do (Common Mistakes)

Here are the mistakes that cause fails:

❌ Installing the green bonding screw in a subpanel
❌ Bonding neutral to the enclosure in a downstream panel
❌ Mixing grounds and neutrals on the same bar in a subpanel
❌ Using neutral as a grounding path
❌ Random “extra bonds” because it “seems safer”

More bonding is NOT safer. It creates parallel return paths.

 

 

How This Connects to Services and Feeders (Quick Link)

This all starts at the service entrance and affects the whole building’s distribution system.

👉 For the bigger picture, read Services and Feeders Explained — because the service is where NEC 250.24 rules begin.

 

 

Why Labels Matter Here Too

Even if your bonding is correct, inspectors and maintenance crews still need things clearly identified.

✅ At Print Pro, we make NEC-compliant electrical labels that help keep service equipment, disconnects, and panels clear, safe, and inspection-ready.

 

 

Pro Tips for Contractors (Simple but Powerful)

  • Neutral and ground get bonded ONE time — at the main service equipment

  • In subpanels: separate neutral bar (isolated) and ground bar (bonded)

  • Always remove bonding screws/straps in subpanels unless it’s service equipment

  • If you see neutral current on conduit or EGCs, suspect an improper neutral-ground bond

  • Take a quick photo inside the service panel before inspection — it helps if questions come up

Grounding and Bonding (NEC)
Approved Grounding Electrodes Explained: NEC 250.52