Grounding gives stray electrical current a safe, low-resistance path back to earth and to your panel, so a fault trips a breaker instead of energizing metal you might touch. Bonding ties metal systems – panel, gas line, water pipe, CSST – together so they all sit at the same potential. Many older San Diego homes have one or both done poorly, or not at all.
Grounding and bonding are two different jobs
People use the words interchangeably, but they solve different problems, and a home can pass on one and fail on the other.
Grounding is about giving fault current somewhere to go. Your electrical system is connected to the earth through a grounding electrode – typically a driven ground rod, a connection to the metal water service pipe, or, in newer construction, the rebar in the concrete foundation (a “Ufer” or concrete-encased electrode). When a hot wire shorts to a metal enclosure, that low-resistance path lets enough current flow to trip the breaker fast. Without it, the metal box or appliance can stay energized and quietly wait for someone to touch it.
Bonding is about keeping everything at the same voltage. If your gas piping, water piping, and electrical ground are all tied together, there is no voltage difference between them for current to jump across. Skip the bonding and a fault can put a few hundred volts between, say, a metal faucet and a gas appliance, which is exactly the scenario that injures people and starts fires.
A general home inspection is visual and non-invasive, so we report what we can see and access. Confirming that an entire grounding electrode system meets current code is the job of a licensed C-10 electrical contractor – but there is a lot a careful inspector can document.
The grounding electrode system
At the service, we look for visible evidence that the system is actually grounded. That includes a grounding electrode conductor leaving the panel or meter, a ground-rod clamp at the base of an exterior wall, or a bonding clamp on the incoming water pipe. In San Diego’s older neighborhoods we frequently find:
- A single ground rod where two may be required. Code generally calls for a second rod unless the first is proven to have low enough resistance, which it rarely is.
- A water-pipe ground that no longer works. Homes from the 1950s-1970s often grounded to a galvanized or copper water main. When a section gets replaced with plastic (PEX or PVC) during a repipe, the electrical ground can be unintentionally disconnected, and nobody notices.
- Corroded or loose clamps. Coastal humidity in Point Loma, Ocean Beach, Encinitas, and Coronado eats hardware. A green, crusty ground clamp may no longer be making a real connection.
- No visible electrode at all. On some very old or DIY-modified systems we simply cannot find evidence of grounding, which is a flag for electrician evaluation.
Bonding: gas, water, and CSST
Bonding is where San Diego’s mix of older homes and newer gas appliances creates real risk. Three pieces matter most.
Metal water piping should be bonded so the whole plumbing system is at ground potential. Again, repipes are the usual culprit – cut in a stretch of plastic and the metal sections downstream can become isolated.
Gas piping must be bonded too. Traditional black-iron gas pipe is often bonded through its connection to an appliance, but that is not something to assume.
CSST – corrugated stainless steel tubing, the flexible yellow (or sometimes black) gas line common in additions, ADUs, and re-piped homes – has a specific and important bonding requirement. CSST is thin-walled, and a nearby lightning strike or electrical fault can arc through it and puncture it, releasing gas. Manufacturers require CSST to be directly bonded with a dedicated bonding conductor (commonly 6 AWG) clamped to the metal fitting near where the line enters the home. We regularly find CSST in San Diego homes with no dedicated bond at all – it is one of the more consequential bonding defects we report, and it gets a clear recommendation for a licensed contractor to correct.
Ungrounded (two-prong) outlets in older homes
Walk through a 1940s North Park bungalow, a Kensington Spanish, or a mid-century La Mesa rancher and you will often find two-prong outlets. Those receptacles have no equipment ground, usually because the home was wired before grounded outlets were standard – sometimes with cloth-insulated wiring or early “knob-and-tube” runs.
The danger is twofold. First, anything you plug in that expects a ground (computers, surge protectors, many appliances) has no protective path. Second – and this is the one we see constantly – a previous owner or flipper simply swapped the two-prong receptacles for modern three-prong ones without running a ground wire. Now the outlet looks safe and accepts a grounded plug, but there is nothing behind the third hole. That is a hidden hazard, and it is exactly why we test.
During an inspection we use a plug-in tester at representative outlets and check for open grounds, reverse polarity, and other miswiring. When we find three-prong outlets with no ground, we document it as a defect, not a cosmetic note. This kind of finding shows up often in our buyer’s inspections on older homes, and it ties directly into the broader picture in our guide to electrical panel problems in older San Diego homes.
Where GFCI fits in
Here is the practical part many homeowners get wrong. If you have an ungrounded circuit, the National Electrical Code actually permits a specific remedy: replacing a two-prong outlet with a GFCI receptacle (or feeding the circuit from a GFCI), labeled “No Equipment Ground.” The GFCI cannot create a ground that isn’t there, but it does protect people from shock by cutting power the instant it senses current leaking where it shouldn’t.
This is a legitimate, electrician-installed fix that makes an ungrounded outlet far safer – but it has limits. It does not provide a true equipment ground for sensitive electronics or surge protection, and it must be labeled so the next person understands the circuit. GFCI protection and grounding are related but not the same thing, which we untangle further in our overview of GFCI and AFCI electrical safety in San Diego.
Why this matters when you’re buying
Grounding and bonding defects are usually invisible from the curb and cheap to fix relative to the risk they carry – but only if someone catches them first. A loose ground clamp, an unbonded CSST line, or a row of fake-grounded outlets won’t show up in listing photos.
If you’re buying an older San Diego home, treat the electrical grounding system as a standard line item. A general inspection documents what’s visible and accessible and tells you where a licensed electrician needs to take the next look – we don’t certify code compliance or replace an electrician’s judgment. To schedule with InterNACHI Certified Professional Inspector Joseph Romeo, contact The Real Estate Inspection Company at (619) 752-4399. As always, verify anything safety-related and have licensed pros confirm before you rely on it.
