Service Entrance Conductor Inspection
Purpose
Every conductor in a building has an overcurrent device ahead of it except these. Service entrance conductors run from the point of delivery to the service disconnect with nothing between them and the utility transformer, so a fault on them clears through the transformer's protection, through the conductor itself, or not at all. That single fact changes what an inspection is looking for. A cracked jacket on a branch circuit is a repair item. The same crack on a service entrance conductor is the start of a fault that no breaker in the building is going to interrupt.
The second reason this gets its own procedure is that the findings sit on both sides of a boundary. The drop or lateral is the utility's; the mast, weatherhead and conductors below the point of attachment are the customer's. A shop that reports everything as its own scope either sells work it cannot do or eats work it should have routed.
Scope
Covers inspecting existing overhead or underground service entrance conductors and their supporting hardware at dwellings and small commercial buildings, single-phase 120/240 V, 400 A or smaller.
Not covered: replacing the meter socket (electrical-meter-socket-replacement-and-utility-coordination), the panel or main breaker behind the disconnect, the grounding electrode system (electrical-grounding-electrode-system-verification), and the whole service upgrade (electrical-service-panel-upgrade).
Roles and handoffs
| Role | Owns | Hands off |
|---|---|---|
| Inspecting tech | Steps 1 to 7, every measurement | Findings graded by consequence to the office same day, with the utility items separated from the customer items |
| Office | Routing the utility-side findings | A written report to the utility, and a copy to the customer so they know what was referred and to whom |
| Estimator | Quoting the customer-side work | The quote with each item tied to its finding, so nothing is bundled into "service work" |
The separation of utility items from customer items is the whole handoff. Bundled together, the customer is quoted for a clearance the utility is responsible for.
Procedure
Assess from the ground before anything is touched or climbed. Look for a conductor down or hanging low, a drop resting on a roof or gutter, vegetation growing through the drop, a mast leaning or pulling from the wall, or a cracked service pole. Accept when none of those are present and the drop is clear of the structure along its whole run. Wrong looks like any of them; stop rule, a down or contacting conductor ends the inspection immediately, everyone is kept back at least the distance the utility specifies, and the utility is called from where you stand. Hazard: a service drop can energize a gutter, a fence or wet ground around a downed conductor, so nobody approaches to look closer and nobody moves the vegetation.
Establish the boundary and write which findings are whose. Identify the point of attachment on the building and the point of delivery your utility defines, because the drop above it is the utility's and the mast, weatherhead and conductors below it are the customer's. The National Electrical Safety Code, ANSI C2, governs the utility side through your state commission's adoption; the NEC governs yours. Accept when the report has two columns and the boundary is named in a sentence. Wrong looks like a report that lists a low drop and a split jacket in the same list; stop rule, an unclear boundary gets a call to the utility before the report goes out. Hazard: none, this is looking and writing from the ground.
Inspect the outdoor termination for the type of service you actually have. Overhead: the weatherhead sits above the point of attachment, the drip loop hangs below the entry so water runs off rather than in, the individual conductors are separated and unabraded, and the mast is plumb and secured. Underground: the riser is undamaged at grade, the sweep and fitting are sound, the raceway is not standing full of water, and there is no evidence of excavation near the run. Accept when every item for your branch is inspected and its condition written, and the other branch is marked not applicable rather than left blank. Wrong looks like a weatherhead below the attachment, so water tracks down the conductors into the socket; stop rule, water tracking is corrected before any other finding is quoted. Hazard: no ladder goes against a mast or a drop, so this is done from the ground or from a ladder set well clear of the conductors.
Measure the clearances that apply to your branch, and record the number rather than a judgment. For an overhead service, measure the lowest point of the drip loop and the drop over each surface it crosses. NEC 230.24 sets these, and for a 120/240 V system, which is 120 V to ground, the figures include 12 ft over residential property and driveways not subject to truck traffic and 18 ft over public streets and areas subject to truck traffic, in the edition your authority having jurisdiction has adopted. Accept when every crossing has a measured height written beside the figure it is judged against. Wrong looks like "clearance looks tight"; stop rule, a measured shortfall over a driveway is not fixed by tightening a drop, it goes to the utility and usually means raising the point of attachment, so it is reported rather than adjusted. Hazard: measuring under a drop with a metal tape or fiberglass rod puts a conductive object near live conductors, so use a laser or a non-conductive measure and keep it low.
Verify conductor type and size against the table that actually governs a dwelling service. Read what is printed on the jacket or the conductor. For service and feeder conductors supplying the entire load of a dwelling unit, NEC Table 310.12 gives the permitted sizes in current editions; that allowance lived at 310.15(B)(7) before the 2020 cycle, so pull the edition your jurisdiction has adopted rather than quoting a section number from memory. Accept when the conductor size, material and the table row are written down together. Wrong looks like a conductor judged against the general ampacity table when the dwelling table governs, which condemns a compliant service; stop rule, an unreadable jacket means the size is confirmed at a termination or reported as unverified, never estimated by eye. Hazard: reading a conductor at a termination means an open enclosure ahead of the disconnect, so arc-rated clothing and one hand in.
Inspect the entry, the physical protection and how far unprotected conductor runs inside. Measure from the point of entrance to the service disconnect, because NEC 230.70 requires the disconnect at a readily accessible location nearest the point of entrance and every foot beyond that is unfused conductor inside an occupied building. Check the raceway or cable for support, damage and a fitting listed for wet locations at the entry, and confirm the service raceway is bonded by a means listed for the purpose rather than by a standard locknut, per NEC 250.92. Accept when the unprotected length is written in feet, the bonding means is named, and the entry is sealed. Wrong looks like a service cable running the length of a basement to a panel somebody relocated; stop rule, an excessive unprotected run is graded as a major finding, not a note. Hazard: an open service raceway means live conductors with no device ahead of them, so nothing is probed and nothing is pulled.
Grade every finding by what its failure does, then write and route it. Three grades: immediate hazard, which is called in today; defect, which is quoted; and observation, which is recorded for the file. Accept when every finding carries a grade, an owner, and the measurement it rests on. Wrong looks like a flat list where a split jacket at the weatherhead sits beside a scuffed mast; stop rule, an immediate hazard is not put in a report and mailed, it is phoned to the utility or the customer before you leave. Hazard: none, a desk step, but a grade that understates a service-side defect is the one mistake this whole procedure exists to prevent.
When the site does not match the assumption
The utility disputes a clearance you measured. Give them the measurement, the surface it crosses and a photograph with a reference in frame, and let them re-measure. Do not touch anything on their side to prove the point.
The customer wants the service entrance cable replaced without touching the panel. Often legitimate, and a real scope. Confirm the outage requirement and the inspection release first, because the conductors cannot be replaced live and the utility disconnect is on their calendar.
The record this produces
- The boundary sentence and the two-column finding list. It is what stops a customer being quoted for utility-side work.
- Every clearance as a measured height beside the figure it was judged against. Read when the utility disputes it, which is the only time an estimate is useless.
- Conductor size, material and the table row. Read by whoever later proposes a larger service or a subpanel off this one.
- Unprotected length in feet from point of entrance to disconnect, plus the bonding means. Read at the next inspection, and most often missing from an old file.
- The grade on each finding, with who it was routed to and when. Read if anything ever burns.
Worked pass: 1978 ranch, overhead 100 A service, drop crossing the driveway
Step 1: drop clear of the roof and gutter, no vegetation in it, mast plumb and its strap tight to the fascia. Passes, so the inspection proceeds. Step 2: point of attachment is the mast eye, so the drop above it is the utility's and everything below is the customer's; the report is set up in two columns with that sentence at the top.
Step 3: overhead branch, and the underground branch is marked not applicable rather than left blank. Weatherhead sits 9 in above the point of attachment, drip loop hangs below the entry, individual conductors separated with no abrasion, mast secured. All written as inspected.
Step 4 fails. The lowest point of the drip loop measures 14 ft 2 in, which is clear, but the drop crosses the driveway and its lowest point over the driving surface measures 10 ft 8 in against the 12 ft figure for a residential driveway not subject to truck traffic at 120 V to ground. Stop rule taken: nothing is adjusted, nothing is tightened. It goes in the utility column, is phoned in the same day, and the customer is told that the likely fix is raising the point of attachment, which is customer-side mast work the utility will require before they re-hang the drop.
Step 5: the jacket reads 2 AWG aluminum SE. For a 100 A dwelling service, the dwelling service and feeder table gives 2 AWG aluminum, so the conductor matches its row and the row is written on the report beside it. Step 6: from the point of entrance to the service disconnect measures 4 ft, the entry uses a fitting listed for wet locations, and the service raceway carries a bonding bushing rather than a standard locknut. All three recorded.
Step 7: three findings graded. The driveway clearance is an immediate hazard, phoned to the utility, owner utility. A weathered but intact jacket at the mast is an observation, owner customer, recorded with a photograph for comparison in two years. The mast strap is a defect, quoted, owner customer, because the point of attachment work is coming anyway.
The report leaves with a measured 10 ft 8 in in it. That number is what makes the utility act, and "clearance looks low" is what makes them ask somebody to go back and measure it.
References
- NEC Article 230, including 230.24 for overhead clearances and 230.70 for service disconnect location, Table 310.12 for dwelling service and feeder conductor sizes, and 250.92 for service raceway bonding, in the edition your authority having jurisdiction has adopted.
- National Electrical Safety Code, ANSI C2, which governs the utility's side of the point of delivery through your state commission's adoption.
- 29 CFR 1910.333(b)(2), with qualified person defined at 1910.332 and 1910.399; NFPA 70E-2021, Article 130, for justification and PPE when equipment ahead of the service disconnect is opened.
- See related:
electrical-meter-socket-replacement-and-utility-coordination,electrical-service-panel-upgrade.