The Electrification Site Survey SOP

Purpose

This survey produces one record that every trade on a conversion can quote from: what the electrical service is, what the house has actually drawn over a year, every gas appliance and what it vents into, where a heat pump water heater can live, where outdoor units can go, and what the envelope looks like. Without it, each trade surveys its own slice on its own visit, the electrician sizes the service against a guess, and nobody writes down that the water heater shares a chimney with the furnace until the furnace is already gone. The survey is look-and-record only: it fires nothing, opens no live equipment and disturbs no insulation.

Scope

Covers: a single-family or small multifamily house being planned for partial or full conversion off gas or propane, on the first planning visit, before any equipment is quoted.

Does not cover: combustion safety testing of the appliances (that is The Gas Appliance Removal and Venting Check SOP, run when an appliance actually comes out), the load calculation itself (See related: Measuring Existing Load Before You Sell a Service Upgrade), the order of the work (See related: The Whole-House Electrification Sequence), or utility and permit coordination for a service change (The Service Upgrade Coordination SOP). A house with an active gas odor, a sounding CO alarm or visible scorching at a draft hood on arrival is not surveyed today; it gets the response in step 1 and a service call.

Roles and responsibilities

The handoff that fails most often is the demand-data request. If it is not sent before the visit, it is not sent, and the load decision gets made on the standard calculation alone.

Procedure

1. Clip on a personal CO monitor and walk in with your senses on. Turn on the monitor outdoors so it zeroes in clean air, then enter. Acceptance: monitor reads 0 to 2 ppm at the door and stays under 9 ppm through the house. Wrong looks like a reading climbing past 9 ppm, a gas odor, or soot at any draft hood. Stop rule: at 35 ppm or any gas odor, everyone leaves the house now, no switches, lights or phones operated inside, and you call the gas utility's emergency line from outside; the survey is cancelled and the office books a service call. Hazard: you enter spaces with unchecked combustion, so the monitor goes on before the door opens.

2. Read the service and the panel from the outside of the equipment. Record the main breaker rating, the meter type, whether the service is overhead or underground, the panel's bus rating from the label inside the door, the count of full-size spaces and how many are empty, and any tandem or double-stuffed breakers. Acceptance: main rating, bus rating and space count all written down, with a photo of the panel label and the full breaker directory. Wrong looks like a main larger than the bus rating, a panel with no legible label, heat discoloration at a breaker, or a hot smell. Stop rule: any of those, flag it for an electrician on the record card and do not quote electrical work off this survey. Hazard: do not remove the dead-front. Service entrance conductors have no disconnect above them except the utility's, so they are live with the main off; reading conductor size behind the cover is an electrician's task under the shop's NFPA 70E 130.5 risk assessment, with arc-rated PPE chosen for that task.

3. Request the utility's demand data and confirm what it will contain. With the account holder, submit the release through the utility's customer portal (many utilities offer a standardized download often called Green Button) for 12 months of interval data. Acceptance: the release is submitted and you know the interval length, 15 minutes or hourly. Wrong looks like hourly-only data, fewer than 12 months, a recent change in occupancy (a new household member, a home office, an EV bought in the last year), or onsite solar. Stop rule: any of those, note that the 12-month data does not stand on its own and that the electrician will need a 30-day recording instead or in addition. Under NEC 220.87 (2023 edition, as adopted by your jurisdiction), a year of maximum demand data or a 30-day recording at 15-minute intervals that captures the larger of the heating or cooling load can replace part of the standard calculation, and the 2020 and 2023 editions exclude a service with solar or peak shaving from that method. Hazard: none physical; the data goes only to the shop's load file.

4. Inventory every gas appliance and trace what it vents into. For each one, record type, input rating in Btu per hour from the rating plate, venting category (natural draft with a draft hood or diverter, induced draft, or sealed direct vent), and the vent path to the outdoors: which chimney or vent, lined or unlined, shared with what. Acceptance: every appliance has a rating and a traced vent, and every shared vent is listed with all its appliances. Wrong looks like two natural-draft appliances in one masonry chimney, an unlined masonry flue, a vent connector sloping down toward the chimney, rust or white staining at the thimble, or an appliance you cannot trace. Stop rule: a shared masonry chimney goes on the record as a mandatory venting check the day the first appliance on it is removed; an untraceable vent is flagged for the HVAC or gas trade before any removal is quoted. Hazard: you are reading, not testing, so do not fire or adjust any appliance and do not open a vent connector; leave appliance controls exactly as found.

5. Measure the water heater space for a heat pump unit. Record the room's length, width and ceiling height and compute its volume in cubic feet, the typical air temperature, the floor drain or condensate route, the nearest receptacle and its circuit, and whether a door closes the space off. Acceptance: volume at or above the minimum the candidate unit's manufacturer states (often several hundred cubic feet, less with a louvered door or ducting), plus a named condensate route. Wrong looks like a closet well under that volume with a solid door, no drain path within reach of a condensate pump, or a space that drops below about 40 F in winter. Stop rule: any of those goes on the card as "HPWH needs ducting, relocation or a split unit; plumber to confirm" rather than a yes. Hazard: keep hands off the hot flue connector and do not move the gas valve. See related: Heat Pump Water Heater Reference.

6. Walk the outside for outdoor unit locations. For each candidate spot, record distance to the planned indoor unit or air handler, clearance to walls and windows, the height snow reaches, where defrost meltwater will run, and the disconnect location in sight of the unit (NEC 440.14, as adopted). Acceptance: at least one spot on a level base above the local snow line, with meltwater draining away from walks and the foundation, and a line set route under the length the equipment literature allows. Wrong looks like the only spot under a roof valley, beside a bedroom window on a tight lot, or draining onto a walkway that will ice. Stop rule: no acceptable spot is recorded as such, and the HVAC lead decides on a wall bracket or a different system before quoting. Hazard: check overhead before lifting a tape or ladder near the service drop, and watch for buried lines before marking a pad; the survey does not dig.

7. Note the envelope from the attic hatch and the living space. Record insulation type and depth at the hatch, obvious bypasses (open chases, unsealed top plates, recessed lights) and window type. Acceptance: a depth in inches and a type, and a yes or no on visible bypasses. Wrong looks like loose gray-brown granular fill, which may be vermiculite that can contain asbestos, or knob-and-tube wiring buried in insulation. Stop rule: suspected vermiculite is not touched, sampled or walked through; the card says "suspect vermiculite, no disturbance, test before any attic work." Hazard: view from the hatch rather than walking the attic; if you must step in, stay on framing members, not drywall, and wear an N95 or better for fiberglass, but never enter loose fill you suspect is vermiculite.

8. Close the visit with the customer and file the card. Ask the occupancy questions the load and comfort work depends on: how many people, typical thermostat settings, any setbacks, EV now or planned and when it charges, medical equipment that needs power, and what the customer most wants from the conversion. Acceptance: every field on the record card filled or marked "not available, reason given", and the office has the card the same day. Wrong looks like a blank field with no reason. Stop rule: a blank load or venting field holds the quote; the office does not price the job until it is filled. Hazard: confirm you left every appliance control, panel door and attic hatch as found before you leave the house.

The record this produces

One survey card per house, filed to the customer record, read by every trade that quotes the job and by the tech who comes back in two years.

ELECTRIFICATION SURVEY  - 1958 two-story, 1,900 sq ft
SERVICE  100 A main, 125 A bus, overhead, 24 sp, 2 empty
DEMAND   release sent, 15-min, 12 mo; EV bought 5 mo ago
         -> 30-day recording needed (data predates EV)
GAS      furnace 80,000 Btu/h nat draft  -> masonry chim
         WH 40,000 Btu/h nat draft       -> same chimney
         range 60,000 Btu/h, unvented
         dryer 22,000 Btu/h -> wall vent
         FLAG: shared unlined masonry, vent check at
         first removal
HPWH     basement 1,150 cu ft, 58 F winter, floor drain
OUTDOOR  side yard, 14 ft to air handler, snow 10 in
ENVELOPE 4 in fiberglass at hatch, open plumbing chase
FLAGS    none electrical; CO max 1 ppm

Worked pass

The card above is a real run of this procedure on a 1958 two-story.

Step 1 (CO and senses): monitor zeroed outdoors, 1 ppm maximum through the house. Pass.

Step 2 (service and panel): 100 A main on a 125 A bus, 24 spaces, 2 empty, no discoloration, directory photographed. Pass.

Step 3 (demand data): release submitted, 15-minute intervals, 12 months available. Then the occupancy question from step 8 surfaced early: the household bought an EV five months ago and charges it at home. Seven of the twelve months predate the charger, including the whole of last winter. This step failed its acceptance condition and took its stop rule: the card records that the 12-month data does not represent the current load, and the electrician schedules a 30-day recording that spans a cold stretch with the charger in use. Under NEC 220.87 as adopted here, a year of data that predates a new load does not show that load, so the 12-month file is kept for context only.

Step 4 (gas inventory): four appliances. Furnace and water heater share an unlined masonry chimney, which is exactly the case where removing the furnace first leaves 40,000 Btu/h alone in a flue that also carried the furnace's 80,000. The card carries the flag forward. See related: What Removing a Gas Appliance Does to the Ones Left.

Step 5 (HPWH space): 1,150 cubic feet of basement at 58 F in winter, floor drain 6 feet away. Pass against the unit under consideration.

Steps 6 to 8: as carded above; every field filled, card filed the same afternoon.

The number the quote most depended on was the step that failed, and it failed on one occupancy answer, not on anything visible at the panel.

References

• NFPA 70, National Electrical Code, 220.87 and 440.14 (2023 edition), as adopted by your jurisdiction
• NFPA 70E (current edition), Standard for Electrical Safety in the Workplace, 130.5 risk assessment
• See related: The Whole-House Electrification Sequence
• See related: Measuring Existing Load Before You Sell a Service Upgrade
• See related: Heat Pump Water Heater Reference