Guide to Local Law 157

The Importance of Natural Gas Detection

Your resource of the latest amendments, compliance updates, and technology solutions for mitigating environmental, safety, health and financial risks with natural gas leak detection

  • Give current information on the status of Local Law 157
  • Share information on elevating the safety of NYC buildings for residents and communities
  • Detail natural gas detection best practices and relevant requirements
  • Guide those seeking natural gas detection compliance through monitored systems
  • Help landlords and owners avoid non-compliance, costly fines, and risks to health and safety
Information current as of 02/14/2024

This guide is intended for those interested in natural gas detection in relation to Local Law 157 of the New York City Rules - including legislators, developers, building boards and managers, and information seekers on legislation status and relevant requirements. As the legislation progresses, information is regularly updated by ProSentry’s team of experts in smart monitoring systems for New York residential and commercial multi-family/unit real estate. The purpose of this guide is to:

01. Executive Summary

Executive Summary: After two fatal gas explosions in 2014 and 2015, New York City Council passed Local Law 157 requiring all residences in NYC to have natural gas detection once there was a national standard. That national standard was published in 2022 and the DOB has since released its Final Rule, which went into effect on February 15, 2024. Requiring compliance on or before May 1, 2025, the law specifies that compliant gas detectors should be placed within one foot of the ceiling and at least 3 feet and no more than ten feet horizontally from all gas appliances. These gas detectors can be monitored and part of a system, or unmonitored. Buildings with monitored systems have the advantage of direct notification to building staff as soon as a gas leak is detected, allowing building staff to respond quickly to the site of the leak and potentially avoid whole building gas shut downs.

02. About Local Law 157

What is Local Law 157?

Local Law 157 - also known as Local Law 157 of 2016, LL157 and the gas detector law - is a citywide ordinance that requires the mandatory installation of carbon monoxide / smoke detectors and natural gas detectors in New York City residences once an industry standard had been established. It amended the NYC Housing Maintenance Code, which repealed sections 27-2045, 27-2046, 27-2046.1 and 27-2046.2 of the administrative code of the City of New York relating to smoke and carbon monoxide detecting devices. This standard was published in April 2022 as NFPA 715 by the National Fire Protection Association. Read Local Law 157 in its entirety.

What is the current status of Local Law 157?

  • 2016: NYC Local Law 157 was originally passed.
  • April 2022: The standard for the installation and location of Natural Gas Detectors was established by the National Fire Prevention Association as NFPA 715.
  • October 19, 2023: The Commissioner of the Department of Buildings published a proposed rule amending Chapter 900 of Title 1 of the Rules of the City of New York by adding a new Section 908-02: Standards for Installation and Location of Natural Gas Alarms.
  • November 20, 2023: The hearing for public comment was held on the October 19th amendment.
  • February 15, 2024: The Final Rule was published amending Chapter 900 of Title 1 of the Rules of the City of New York by adding a new Section 908-02: Standards for Installation and Location of Natural Gas Alarms.
  • May 1, 2025: Compliance is required for all New York City residences.

What properties need to comply with Local Law 157?

  • As defined by the Housing Maintenance Code, the properties that must comply with Local Law 157 include private and Class A and B multiple dwellings.
  • Private dwellings are permanent dwellings.
  • Class A multiple dwellings are one and two-family houses.
  • Class B multiple dwellings are transient housing such as hotels, lodging houses, dormitories, etc.

What type of gas detectors comply with Local Law 157?

  • The gas detectors that comply with Local Law 157 are natural gas detectors that meet the requirements of NFPA 715-2023, installed within one foot of the ceiling, and no less than three feet or no more than ten feet from each gas appliance.
  • The detectors must be labeled UL1484 or UL2075.
  • The devices can be hardwired, plugged into a constant power source, or battery-powered by a listed monitored low-power radio wireless system.
  • In existing buildings, any of the above are allowed.

What are the natural gas detector installation requirements that comply with Local Law 157?

The natural gas detector installation requirements that comply with Local Law 157 include:


  • Hard-wired detectors require installation by a licensed electrician.
  • Detectors powered by a battery or a plug in power source require installation by building owners, maintenance personnel, or tenants.
  • In the case of kitchens and laundry rooms that don’t have an outlet within a foot of the ceiling and to avoid unsafe and unsightly draped cords, the standard for compliance will likely be battery-powered devices to avoid the disruption and expense of installing a new electrical outlet near the ceiling.
  • Monitored sensors that are part of a low-power radio wireless system such as LoRaWAN, like those provided by ProSentry, deliver near-instant notifications and relay the exact location of the gas leak (this includes the address, apartment number, and the precise locale or appliance within the unit), and allow the building staff to respond quickly and efficiently.
  • The results of complying with installation standards are lives saved and potentially avoiding the costly and damaging process of having the building’s gas shut off.
  • The final rule was published on February 15, 2024, with detectors to be installed by May 1, 2025.

How does Local Law 157 compare to Proposed State Law S3705 proposed for the 2021-2022 session?

Proposed New York State Senate Bill S3705 required that all residences in New York State have monitored natural gas detection and that those sensors would eventually report these leaks to the State. There have been 51 gas explosions in New York State over the last 13 years. As of this writing, New York State Senator Leroy Comrie is consulting with stakeholders about amending this bill, consistent with the new NFPA and Underwriter’s Laboratory standards, which state that notifications must go to a licensed and staffed central station, which alerts the building, 911, and utility company.

03. The Importance of Gas Detection

03. The Importance of Natural Gas Detection

Why was Local Law 157 passed?

The passing of Local Law 157 followed three fatal incidents in New York and several other occurrences throughout the United States. As a result, the NYC Mayor’s office, City Council, Department of Buildings, Fire Department, and construction industry reviewed the regulations and procedures that governed gas piping permitting and installation. Consequently, they passed a series of Local Laws that affected gas piping permitting, installation, and inspections.

  • March 12, 2014: A gas explosion occurred at 1644–1646 Park Avenue, New York, NY killing eight people and injuring more than 50.
  • March 26, 2015: Another gas explosion occurred at 121 Second Avenue, New York, NY. Two people died and 22 were injured. Additionally, an estimated 250 firefighters were involved. The fire from this second explosion also destroyed three buildings.
  • August 21, 2015: A third blast occurred at John F. Kennedy High School in The Bronx, NY. Three workers were injured.

What are the risks of not having monitored gas in a NYC dwelling?

Risks of not having monitored gas in a dwelling include:


  • Safety Risks: Natural gas is explosive at 5% by volume (gas in air) in a room. This percentage is called the Lowest Explosion Limit (LEL). Natural gas alarms alert at 10% of the LEL or 0.5% of natural gas by volume in a room. Natural gas also displaces oxygen, which can lead to asphyxiation.
  • Financial Risks: Firefighters and utility personnel that respond to reported gas leaks slowly move sensors through the building to locate its source. If not found quickly, natural gas leak concentrations can climb above the LEL and threaten the safety of the building, its occupants, and first responders. To avoid a harmful situation and when the location process takes too long, first responders turn off the building’s gas, leaving building staff responsible for locating the source of the leak. For New York utility companies to turn the gas back on, they must carry out and witness a pressure test. When conducting a pressure test, the local utility company runs three pounds of pressure through a domestic building’s gas lines, 600% more than the typical half-pound of pressure. Since most New York buildings have older piping, they often fail the test. As a result, the building is re-piped or converted to electric stoves and dryers. Both efforts are costly, forcing building owners to spend hundreds of thousands–if not millions–of dollars and leaving residents without gas for months.

04. Compliance with Local Law 157

Is there a service that analyzes buildings for Local Law 157 compliance?

Committed to staying at the forefront for updates on  Local Law 157 and NYC Rule Section 908-02, ProSentry is the most reliable New York leak detection company bringing industry-leading innovation to natural gas leak detection solutions for residential and commercial multi-family/unit real estate.

Do carbon monoxide detectors detect natural gas leaks?

No. Carbon monoxide detectors do not detect natural gas leaks.

What is a ‘monitored’ gas leak detector?

While local gas detectors sound an alarm to alert building owners in the event of a leak, monitored gas detectors are continuously remotely monitored to alert both building owners and proper authorities in the event of a leak. The advantages of monitored gas detectors over local gas detectors include:

  • Safety: 6% of fire-related deaths result from malfunctioning hard-wired smoke detectors or a lack of power. Monitored detectors regularly check in and notify building staff, if a detector fails to respond. As a result, municipalities now recognize battery-powered smoke detectors that are part of a monitored system to be equivalent, if not better, than hard-wired devices.
  • Speed: ProSentry’s smart sensors provide round-the-clock monitoring and update the user’s personal dashboard–located on the ProSentry platform–with real-time insights, instantly alerting building staff when a concern is detected. When ProSenrtry’s all-in-one wireless smart sensor monitoring solution detects a potential concern, building staff is alerted to assess the situation and in many cases, address it before the tenant returns home from work.
  • Savings: ProSentry’s wireless smart sensor monitoring solution is cost-effective and usually operates for ten years on one battery.

What is a ‘smart-sensor’ gas leak detector?

Amplifying the benefits of monitored leak detectors, smart-sensor gas leak detectors additionally provide instant and continuous information to a staffed central station to help manage the gas leak event - including the exact leak location (specific building, unit, and appliance) and specifics (concentration of gas within the unit) with 30-second updates. Central station staff remains on the phone with 911 so first responders have up-to-the-moment information on the percentage risk of an explosion, safely guiding their response.

How does ProSentry help buildings comply with Local Law 157?

ProSentry is a trusted New York natural gas leak detection service provider for residential and commercial multi-family/unit real estate. ProSentry utilizes an ecosystem of wireless smart-sensors to provide real-time natural gas monitoring, information and alerts via its industry-leading platform. ProSentry’s smart sensors are placed near gas appliances in individual units and connect to wireless LoRaWAN (Long Range Wide Area Network) gateways placed every few floors in building stairwells to communicate detection data. Activated by scanning QR code and integrated with the ProSentry mobile app, each smart sensor is easily programmed with custom location and contact information. In the event of a leak, contacts are instantly notified via preferred communication methods, including text, email, app notification, and live operator call to the building’s front desk, resident manager, and relevant services in the case of emergency. ProSentry’s four call centers are UL-certified according to NFPA 715’s call center compliance regulations, fluent in English and Spanish and located across the country to ensure the strongest, most reliable service.

05. Enhanced Building Safety & Risk Mitigation

What are the signs of a natural gas leak?

According to Constellation Energy, the signs of a natural gas leak include: 


  • A rotten egg smell. Utilities add an odor to odorless natural gas to help detect and locate the leak.
  • Hissing sounds
  • Air bubbles
  • Dying plants
  • Health symptoms associated with exposure to lower gas levels are headaches, dizziness, fatigue, nausea, and irregular breathing. In addition, health concerns caused by high levels of gas exposure are fatigue, severe headaches, memory problems, loss of concentration, nausea, loss of consciousness, and suffocation.
  • Higher than normal gas usage

How does ProSentry enhance building safety and mitigate risks?

ProSentry provides targeted smart-sensors for natural gas monitoring and a full scope of building-wide solutions, including water and oil leaks; temperature and humidity; cigarette and vape smoke; garbage and drain overflows; doors and windows ajar; boiler, exhaust fan and elevator functions; mice and other pest activity, automatic shut-off valves; and water usage meters. The ProSentry Platform streamlines smart sensor data to deliver real-time detection, insights, and alerts for risk prevention and response. By alerting selected contacts and with instant and specific information about the exact location and nature of a leak or other issue, ProSentry enables fast and effective response to save lives, property, and resources.

How can I make my building present-ready and future-proof?

You can make your building present-ready and future proof with responsive technology solutions for natural gas leak detection and other costly risks, including water leaks, mechanical malfunctions and more.

ProSentry’s cost effective, smart building platform integrates targeted risk prevention solutions into scalable, building-wide systems for immediate and effective action. Streamlining an adaptable smart sensor ecosystem with real-time detection, insights, and alerts, ProSentry brings practicality and proactivity to better building management. Elevated health and safety, tenant satisfaction, and property values and revenues are simpler and smarter with the round-the-clock protection of ProSentry on your team.

Contact ProSentry’s team of experts to learn about smart natural gas leak detection and how to make your building present-ready and future-proof with a custom smart sensor ecosystem for your property. Visit the Knowledge Base for more insights, innovations and updates.

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