A restaurant gas install starts with a load count: every appliance's Btu rating, added up, sets the pipe size and tells Southwest Gas what meter you need. Then come permit drawings, black iron piping with a shutoff at each appliance, listed hoses and restraints for equipment on casters, a pressure test, a city inspection and the gas turn-on.
Step 1: Count the gas load
Every gas appliance has a rating plate with its input in Btu per hour. The fuel gas code sizes pipe on the total. Section 402.2 of the 2024 International Fuel Gas Code, which Phoenix enforces, says the flow to provide is "the sum of the maximum input of the appliances served," sized "assuming that all appliances could be operating at full capacity simultaneously." A smaller figure based on diversity is allowed only "where a diversity of load can be established." A busy kitchen at lunch rush is exactly where everything does run at once, so most restaurant designs use the full total.
Build the list before anyone orders pipe:
- Every range, fryer, griddle, charbroiler, oven, wok and steamer on the cooking line.
- Water heaters or boilers, which can carry a big share of the total. See whether a bigger water heater needs a bigger gas line.
- Rooftop units or make-up air heaters if they burn gas.
- Anything planned for later, like a second fryer or patio heaters. Adding capacity during the build is far easier than re-piping an open restaurant.
Gas pipe is sized in cubic feet per hour. Natural gas carries roughly 1,000 Btu per cubic foot in most sizing tables, so a 150,000 Btu fryer needs about 150 cubic feet per hour. Southwest Gas's Arizona tariff puts its gas at an average of "not less than 900 Btus per cubic foot," so your designer uses the value the utility gives for your area.
Step 2: Design and permit the piping
A new commercial gas system needs a permit and, in Phoenix, plan review. The city's gas piping plan review checklist asks for:
- A site plan with the gas meter marked existing or new, with its capacity.
- A one-line piping diagram with sizing calculations and every branch length and valve.
- Each appliance's location and Btu/hr input rating.
- The total developed length from the meter to the most remote appliance.
- The supply pressure, the pressure after each regulator, and the code table used.
- For gas delivered at 2 psi or more, a written confirmation letter from Southwest Gas placed in the drawing package.
Pipe size depends on two numbers: total load and the longest run. The code's sizing tables show why length matters. At standard pressure, a 1-inch steel pipe carries 215 cubic feet per hour over 50 feet but only 148 over 100 feet, per Table 402.4(1). Kitchens at the far end of a long strip center often need a bigger main than people expect. Our guide to whether a restaurant gas line can handle a new fryer or range walks through that math.
Step 3: Install the pipe, valves and connectors
The piping usually runs along the wall behind the cooking line to a manifold with an outlet for each appliance. The code adds a few requirements that matter every day in a restaurant:
- A shutoff valve for every appliance. Section 409.5.1 puts it in the same room, within 6 feet, and upstream of the connector. A valve behind movable cooking equipment counts as accessible.
- A sediment trap (a capped tee, sometimes called a drip leg) as close to the appliance inlet as practical, per Section 408.4, unless the appliance has one built in. Ranges and outdoor grills are exempt.
- Listed hoses for anything on casters. Section 411.1.1 requires commercial cooking appliances on casters, or moved for cleaning, to connect with a connector listed to ANSI Z21.69/CSA 6.16, and their movement "shall be limited by a restraining device." Our page on gas hoses and restraint cables for equipment on casters covers sizing and the cleaning routine.
- Regulators where pressure is elevated. If the building gets 2 psi, a line regulator drops it to what the appliances need before it reaches the hoses. Dormont's instructions limit its commercial connectors to gas at no more than 1/2 psi.
The hood system ties in here too. Phoenix's fire code, Section 904.14.2, says that when the hood's fire-extinguishing system fires, it "shall automatically shut down the fuel and electrical power supply to the cooking equipment," with a manual reset. That means a gas shutoff valve in the line feeding the appliances under the hood. The valve sits in the gas piping, but the suppression system that trips it is installed and serviced by a fire suppression contractor. Our page on the kitchen hood gas shutoff valve explains how it works.
Step 4: Test, inspect and turn on the gas
Before any gas flows, the new piping gets an air test and a city inspection. Section 406.4.1 sets the test at 1.5 times the working pressure and never below 3 psig. Section 406.4.2 sets the time at half an hour for each 500 cubic feet of pipe volume. Any drop on the gauge counts as a leak until it's found and fixed. Our guide to how a gas line pressure test works goes step by step.
Once the inspector signs off, the city issues a gas clearance. Southwest Gas won't set a meter or turn on gas without it. Its commercial meter set process says "Notification of Gas Inspection and Clearance of the customer's house line, by the governing municipality, must be received by Southwest Gas."
### The meter and the turn-on
For a new building or a bigger meter, Southwest Gas works in two phases: underground facilities (main, service line and riser), then the meter set. Its Central Arizona commercial package lists the points restaurant owners trip over:
| Southwest Gas requirement | What it means for your schedule |
|---|---|
| Underground work starts at least 6 weeks after signed paperwork | Apply as soon as the load is known |
| Main design, permits, land rights or elevated pressure add 6 more weeks | A 2 psi request can push a minimum of 12 weeks |
| Loads over 1,000 cubic feet per hour may need a rotary meter designed and built | Two weeks minimum, four weeks over 7,000 |
| Meter set no sooner than 5 working days after the city clearance (8 over 1,000 cubic feet per hour) | Book inspection early |
| Elevated pressure needs written approval before the house line goes in | Without it, no meter set |
At turn-on, the utility runs its own leak check. Its tariff makes the customer responsible for "a leak tight system for receiving gas" and denies service if leakage exists. Then every appliance gets purged and lit, and the code requires the connections checked for leaks before the kitchen goes into service.
### What about a tenant space that already has gas?
A second-generation restaurant space still needs most of these steps whenever the lineup changes. Phoenix's gas clearance table, published with Southwest Gas and the Arizona Corporation Commission, lists new piping, changes to existing piping, and "an increase in BTU consumption requiring piping capacity calculations" as permit work with a city inspection. Swapping an appliance in kind on its connector, with no piping change, doesn't need one. Our guide to commercial tenant improvement plumbing covers the rest of a restaurant build-out.
HQ Plumbing & Air installs and repairs commercial gas lines for restaurants across the Phoenix area, from load calculations and permits to the pressure test and the city clearance. We're licensed and insured, and you get a free estimate with the price up front before work starts.
Count the load first. Everything else follows from that number.