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I just moved into a house built back in 1961. The house was totally rewired in 2018 so is up to code. The garage is detached and has two old 2-wire, 15 amp 120 volt circuits with no ground wire coming from the 100-amp main panel in the house. To bring the garage up to code with a ground wire, can I simply add a ground rod next to the garage and use that as my AC ground?

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    Are the circuits to the garage in conduit?
    – JACK
    Sep 7, 2021 at 17:05
  • .. and if those circuits to the garage happen to be in metallic conduit, can you verify it is electrically continuous end-to-end? If you're comfortable with removing the "dead front" face of the circuit breaker panels at the house and detached garage, share a few photos of their interior and immediate surroundings with us. That'll help us provide suggestions tailored to your circumstances.
    – Greg Hill
    Sep 7, 2021 at 17:23
  • If you install a GFCI breaker per circuit (2?) in the house panel then you'll be good to go; hopefully they're not MWBC'd. You'll notice in your house panel that your neutral and ground is bonded so I don't believe your ground rod idea is up to code.
    – MonkeyZeus
    Sep 7, 2021 at 18:08
  • 1
    Yes, do you know what wiring method was used to run the garage circuits? Sep 8, 2021 at 0:05

2 Answers 2

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The Code says you can simply replace the receptacles with GFCI's, but you can't connect to a ground or interconnect the grounds:

406.4(D) Replacements (2) Non–Grounding-Type Receptacles. Where attachment to an equipment grounding conductor does not exist in the receptacle enclosure, the installation shall comply with (D)(2)(a), (D)(2)(b), or (D)(2)(c).

(a) A non–grounding-type receptacle(s) shall be permitted to be replaced with another non–grounding-type receptacle(s).

(b) A non–grounding-type receptacle(s) shall be permitted to be replaced with a ground-fault circuit interrupter-type of receptacle(s). These receptacles or their cover plates shall be marked “No Equipment Ground.” An equipment grounding conductor shall not be connected from the ground-fault circuit-interrupter-type receptacle to any outlet supplied from the ground-fault circuit-interrupter receptacle.

(c) A non–grounding-type receptacle(s) shall be permitted to be replaced with a grounding-type receptacle(s) where supplied through a ground-fault circuit interrupter. Where grounding-type receptacles are supplied through the ground-fault circuit interrupter, grounding-type receptacles or their cover plates shall be marked “GFCI Protected” and “No Equipment Ground,” visible after installation. An equipment grounding conductor shall not be connected between the grounding-type receptacles.

Informational Note No. 1: Some equipment or appliance manufacturers require that the branch circuit to the equipment or appliance includes an equipment grounding conductor.

Informational Note No. 2: See 250.114 for a list of a cord-and-plug- connected equipment or appliances that require an equipment grounding conductor.

404.6(D)(2)(a) doesn't apply because (D)(3) says receptacle replacements must be GFCI where the code elsewhere requires protection, and receptacles in garages now require protection.

If a route exists you could instead add a ground wire back to the grounding electrode system for the house, and then a ground wire would exist and then you could connect the grounds.

250.130(C) Nongrounding Receptacle Replacement or Branch Circuit Extensions. The equipment grounding conductor of a grounding-type receptacle or a branch-circuit extension shall be permitted to be connected to any of the following:

(1) Any accessible point on the grounding electrode system as described in 250.50

(2) Any accessible point on the grounding electrode conductor

(3) The equipment grounding terminal bar within the enclosure where the branch circuit for the receptacle or branch circuit originates

(4) An equipment grounding conductor that is part of another branch circuit that originates from the enclosure where the branch circuit for the receptacle or branch circuit originates

(5) For grounded systems, the grounded service conductor within the service equipment enclosure

(6) For ungrounded systems, the grounding terminal bar within the service equipment enclosure.

Any splice must be in a junction box.

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If the connection for the garage subpanel is in metallic conduit, that serves as the ground. Visually inspect the connection from the main panel that leads to the subpanel, and the connection that comes up into the subpanel.

If they are PVC or something other than metallic conduit then it's not grounded.

If there is metallic conduit on both ends then you need to do a continuity test with a multimeter to verify a continuous ground path. Sometimes people will stub up with rigid conduit and changeover to PVC underground because it's cheaper and allowed by code if a ground wire is ran.

Continuity test. Turn off all power to the subpanel and follow proper safety procedures when working in a live panel. Pick a wire that heads out to the subpanel and disconnect it from both ends. On one end secure the wire to the ground bar. Turn multimeter to resistance/continuity/ohm symbol. On the other end, touch one lead to the wire you disconnected and the other to the ground bar. If there's a continuous path then the meter will chirp. Reconnect the wires and turn power back on.

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