How long does it take to bond metallic water & gas piping (nec §250.104)?

This task typically takes 45–90 minutes to complete, depending on your experience level and the specific conditions of your electrical plumbing system.

What tools do I need to bond metallic water & gas piping (nec §250.104)?

You'll need the following tools: Voltage tester, Multimeter, Wire strippers, Wire brush. Make sure all tools are in good condition before starting.

Is this task suitable for beginners?

This task is rated as Moderate difficulty. This task requires some plumbing experience and intermediate DIY skills.

All guides

ElectricalIntermediate

Bond Metallic Water & Gas Piping (NEC §250.104)

Time

45–90 min

Steps

Pre-check

9 items

Skill

Intermediate

Scope

Bond metallic water piping and gas piping to the electrical grounding system per NEC §250.104. Frequently missed during plumbing work that replaces a section of metal pipe with plastic — the plastic section breaks the bond and energizes the downstream metal under a fault. This is the electrical guide most relevant to the plumbing audience.

Safety

Read before starting

Lower-energy than panel work, but the work happens at the service equipment — the line side is utility-fed and stays energized. NFPA 70E §120.5 verification before any work at the panel. If the bond is missing or broken, accessible metal piping can become energized under a single-fault condition.

Pre-Check

9 items · complete before you start

Confirm circuit identification at the panel — note breaker number and amp rating
Required
Trace the circuit before you cut power so you know which breaker to lock. Mis-identification is the single most common cause of "I thought it was off" incidents.
Non-contact voltage tester proven against a known-live source IMMEDIATELY before use
Required
Test the tester on a live receptacle in the same room. UL-rated testers can fail silently — proving it on a known source is the only way to trust a zero reading.
Lockout-tagout device for the breaker if anyone else could re-energize it
Required
A breaker lock is ~$8. If you are home alone with the only key, a printed tag on the panel is the minimum.
Insulated tools (1000 V rated screwdrivers and pliers)
Required
Standard hardware-store handles are not insulated for live-electrical work.
Safety glasses and dry, insulating footwear
Required
Concrete/wet floors are a parallel path to ground. Stand on a dry rubber mat if the floor is questionable.
Working flashlight or headlamp independent of room lighting
Required
When the breaker goes off, room lights on the same circuit go with it.
Identify all metallic piping systems in the home
Required
Cold water (incoming service + interior distribution), hot water (out of the heater), gas piping (if metal — CSST and rigid black iron both require bonding per §250.104(B))
Locate any plastic sections that break a metal-bond path
Required
Common spots: a PEX repair in the middle of a copper run, plastic dielectric unions at the water heater, CPVC service entrance feeding interior copper. Each break needs the metal section on the downstream side independently bonded — or, simpler, a jumper across the plastic section.
#6 AWG bare or insulated copper bonding jumper, plus listed ground clamps
Required
NEC §250.104(A)(1) — bonding jumper sized per §250.66 (≥#6 copper for most residential services).

0 / 41 complete

Inspect the existing service-entrance bond

Open the main service panel cover (see Establish electrically safe condition step below)
Look for an existing bonding conductor from the panel ground bus to the incoming metal water service — usually #6 bare copper
The clamp lands within 5 ft of the water-service entrance to the building (NEC §250.52(A)(1))
If you find no bond — that is the #1 finding to fix
Photograph the existing bond from panel to first clamp for your records

Code notes

NEC §250.104(A) — interior metal water piping must be bonded to: the service equipment, the grounded conductor, the grounding electrode conductor, OR the grounding electrode itself.
NEC §250.52(A)(1) — metal underground water pipe ≥10 ft contact qualifies as a grounding electrode; must be supplemented by another electrode.

Establish electrically safe condition at the panel

Turn off the MAIN breaker
Lock and tag the main
Test your non-contact tester on a known-live source elsewhere
Verify zero energy at the bus bars (line side stays hot)
Re-test the tester on the known-live source

⚠ Warnings

Bonding conductor work at the panel exposes you to the bus bars — stay below the main breaker.

✅Continue Gate:Have you (1) turned off the breaker, (2) tested your non-contact tester on a KNOWN-LIVE source, (3) verified zero energy at the conductors you are about to touch, and (4) re-tested the tester on the known-live source to confirm it still works? (NFPA 70E §120.5)

Install the water-pipe bond (if missing)

Land a #6 bare copper conductor on the panel's ground bus
Route to the incoming water service pipe (the cold water entrance)
Attach with a listed ground clamp within 5 ft of the building entrance
Clean the pipe surface bright with emery cloth before clamping — corrosion = high resistance = bad bond
For a PVC water service entering and converting to copper inside: the bond goes on the INTERIOR copper, not the buried PVC

Water & Gas Piping Bonding· NEC Wiring

Code notes

NEC §250.104(A)(1) — bonding jumper sized per Table 250.66.
NEC §250.68(C)(1) — interior metal water piping ≤5 ft from entry can be a connection point for the grounding electrode conductor.

Bond around any plastic break

Identify each plastic section in an otherwise-metal system
Install a #6 jumper across the plastic — landed on listed ground clamps on the metal pipe upstream AND downstream
Clean both pipe surfaces bright before clamping
A common plastic break: PEX repair in a copper run. The downstream copper becomes electrically isolated from the bonded portion.
Another common break: dielectric unions at the water heater. The hot-side copper is isolated from the cold-side copper. Bond across with a jumper.

Tips

A dedicated water-heater "dielectric union jumper" is sold pre-made — short #6 copper with two clamps.

Bond metallic gas piping per NEC §250.104(B)

CSST (the yellow flexible gas line) requires bonding to the electrical system at the point of entry to the building, with a #6 copper jumper to a CSST manufacturer-supplied clamp
Rigid black-iron gas piping is bonded by the equipment grounding conductor of the appliance it serves (per §250.104(B) and §250.104(A)(2)) — verify the appliance EGC is intact
Some AHJs require an explicit gas-piping bond even for rigid black iron — confirm locally
Bond goes back to the panel ground bus OR to the grounding electrode system

⚠ Warnings

Unbonded CSST has been linked to fire after nearby lightning strikes — the EGC bond is a safety-critical install requirement.

Code notes

NEC §250.104(B) — metal gas piping that's likely to become energized must be bonded to the service equipment.
CSST manufacturer instructions (TracPipe, Gastite, etc.) specify the bonding clamp and jumper sizing — follow them, the listing depends on it.

Verify continuity and restore power

Visually inspect every new clamp — pipe bright, screw torqued
With panel still de-energized: use a multimeter on continuity (Ω) to verify <1 Ω between panel ground bus and every bonded pipe segment
Reinstall the deadfront
Restore the main breaker
Verify no faults — no breakers tripping, no abnormal smells

Document for the plumbing audience

After plumbing work that adds a plastic section to a metal system: ALWAYS bond across the break before closing the wall
Photo of every bond clamp goes in the home records — the AHJ inspector can't see them after drywall
Note the pipe material change in the plumbing as-built so future trades know

Scope

Safety

Pre-Check

Steps

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