Whole home generator installation, start to inspection

What is whole home generator installation?

A whole home generator is a permanently installed machine that sits outside on a pad, runs on natural gas or propane, and starts automatically within seconds of an outage through a transfer switch. Installing one is a two-trade project: an electrician for the switch and the connection to your service, and a gas fitter or propane supplier for the fuel. The two things that most often stall it are where it is allowed to sit and whether your existing gas supply can feed it.

Signs you need whole home generator installation

• Your area loses power for days rather than hours - ice storms, hurricanes, wildfire de-energisation, or a rural feeder with a long repair queue
• You are on a well, so an outage means no water, no toilets and no washing, and the pump is a hard-wired load a cord cannot reach
• You have a basement with a sump pump and a high water table, where a long outage during heavy rain is a flooded basement
• Someone in the house relies on powered medical equipment, or on refrigerated medication
• You already own a portable generator and have discovered that dragging it out in a storm at night is a thing you will not reliably do

Seeing something not on this list? Browse backup generators problems by symptom →

How whole home generator installation actually works

1. 1

   Site survey before any model is quoted

   A proper first visit looks at four things at once: where the machine can legally and practically sit, where the electrical service and panel are, where the gas meter or a propane tank would go, and how far apart all of those are. Distance costs money in both trades, and the cheapest position electrically is often the worst one for exhaust.

   Watch forA quote produced from a phone call and a square-footage figure. Everything expensive on this job is site-specific, and a number given without a visit is a number that will change.

2. 2

   Sizing - and deciding whether "whole home" means the whole home

   Sizing works from what you want running at once plus the starting surge of every motor load, not from house size. There is a real fork here: buy a machine big enough for the theoretical peak, or buy a smaller one and add load management so the air conditioning, water heater, range and dryer never start together. The second is frequently cheaper for the same lived experience.

   Watch forSizing by square footage. It is the fastest sales method and it ignores whether you have electric or gas heat, one air conditioner or two, a well pump, or an electric range - the things that actually set the number.

3. 3

   Confirm the fuel supply can actually feed it

   This is the most common project-stopper and it deserves to be checked early. A generator is one of the largest gas loads a house can have, and an existing meter and service line sized for a furnace, a water heater and a range may not have the capacity left. The fix - a larger meter or an upgraded service from the utility - is a separate application with its own timeline.

   Watch forA gas load calculation that is not done, or done after the deposit. Ask for it in writing before you commit, along with who applies to the utility if a meter upgrade is needed and how long that typically takes locally.

4. 4

   Establish the setbacks, and the exhaust direction

   Manufacturers specify minimum clearances from the building and from combustible material, and codes set separation distances from windows, doors and air intakes. The reason is carbon monoxide: exhaust from a machine that runs for days must not find a way into the house. On top of that, many jurisdictions and most homeowner associations have their own rules about placement.

   Watch forA location chosen to shorten the cable run, sitting under a bedroom window or beside a fresh air intake. This is the safety decision on the whole project and cable length is not a good enough reason to compromise it.

5. 5

   Check the noise rules and be honest about the neighbours

   These machines are not quiet, and they exercise themselves on a schedule as well as running during outages. Many municipalities have noise ordinances that apply, and associations often add their own limits. Modern enclosures are much better than older ones, and manufacturers publish sound levels at a stated distance - ask to hear one running rather than reading a figure.

   Watch forPlacement against a shared boundary or under the neighbour's bedroom. It is the complaint that arrives after the machine is bolted to a slab and the least fixable one.

6. 6

   Pad, permits and scheduling the two trades

   The machine sits on a level pad - a poured slab or a manufactured composite base - raised clear of standing water and, in cold regions, above expected snow depth. Then the paperwork: electrical and gas permits, sometimes a zoning or association approval, and inspections that have to be scheduled around both trades and the utility.

   Watch forA pad set at grade in a spot that puddles, or an installation that quietly skips permits. Unpermitted gas and electrical work surfaces at sale and can complicate a claim after a fire.

7. 7

   Installation, fuel connection and electrical tie-in

   The machine is set, the gas line run and pressure-tested, the transfer switch installed at the panel or the service, and the control wiring run between switch and machine. Gas pipe sizing over the distance matters as much as the meter capacity - a long undersized run starves the engine under load even when the meter is adequate.

   Watch forPipe sized for the length on paper but routed a much longer way in practice. Ask for the run length used in the sizing to match the run that got installed.

8. 8

   Commissioning, a live outage test, and the handover

   The installer starts the machine, checks it under load, sets the exercise schedule, and - the part that matters - kills the utility supply at the main and lets the whole system perform a real outage from start to transfer to return. You should watch it, be shown how to shut it down manually, and be told what the normal noises are.

   Watch forHandover with no live test and no manual-shutdown demonstration. You need to know how to stop the machine before you need to know how to stop the machine.

What does whole home generator installation cost?

A whole home generator installation is a five-figure project in most cases once the machine, the transfer switch, the pad, the gas work and the permits are counted, and the site conditions move it more than the model does. A gas meter upgrade adds separately. See the generator cost guide.

See the full whole home generator installation cost guide - by material, size and region →

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