Norwich Public Utilities (NPU)

A municipally owned utility serving Norwich, CT with
natural gas, electricity, water and sewer services.


Excess Flow Valve Customer Notification


Excess Flow Valve Customer Notification


As of April 14, 2017 a new federal regulation requires that all natural gas utilities notify customers about the availability of an optional natural gas shut-off device called an excess flow valve (EFV). 

An EFV is a mechanical shut-off device that can be installed in the gas pipe running from the gas main in the street to the gas meter at your property.  An EFV is designed to shut off the flow of natural gas automatically if the service line breaks, for example, by an excavation or digging accident. Stopping the flow of gas from a broken service line significantly reduces the risk of natural gas fire, explosion, personal injury and/or property damage.  Service line breaks are a very rare occurrence in Norwich, however they can occur occasionally.

Only service lines that operate at a pressure above 10 pounds per square inch gage (psig) can have an EFV installed.  EFVs installed on lower pressure service lines are more susceptible to nuisance shut-offs due to the mechanical limitations of the device. 

More than 80% of Norwich Public Utilities’ (NPU) natural gas service lines operate below 10 psig and this new regulation will not apply to those customers. 

NPU has identified all properties that have service lines operating at a pressure above 10 psig and do not already have an EFV installed on the service line.  The addresses of property owners who may request the installation of an EFV are here: eligibility list. 

If your property is not on this list, you are not eligible to request an EFV because:

  •          You have already had one installed,
  •          Your service line operates at 10 psig or below,
  •          And/or your property is a large commercial or high load multi-family service greater than 1,000 SCFH. 

For customers whose service lines operate above 10 psig, NPU has been installing EFVs on all new or replaced service lines since February 2010, in accordance with an existing federal regulation. The new regulation requires natural gas companies to offer EFVs on qualifying service lines that were installed or replaced prior to February, 2010. 

Customers will be responsible for the cost of installation of an EFV. Because EFVs must be installed as close the gas main as possible, the cost will typically involve digging into and repairing a city or state road.  This will result in patching the road at the requesting customer’s property, which increases the installation costs. 

The cost to have an EFV installed is between $2,000-$4,000 depending upon the location of the service line and the age and condition of the road adjacent to your property. If you own a property that is on the eligibility list and would like to have an EFV installed, NPU will work with you to find a mutually agreeable date and time for the work to be completed. The installation of an EFV typically takes one day and should be completed within 3-6 months of your request.

Please contact NPU at This email address is being protected from spambots. You need JavaScript enabled to view it. or NPU’s Customer Service Center at 860.887.2555 to request and schedule the installation of your EFV, or for any additional questions on this program. While scheduling your appointment, we will also a reach an agreement on the cost of and payment for the work. Once you pay for the installation of an EFV you will not be financially responsible for any future maintenance cost of the device. 

Frequently asked questions about EFV process:

Q:    Is there any other way to stop the flow of gas if my service line breaks other than an EFV?

A:    Yes.  Every gas service on the eligibility list has a manual shut-off valve typically installed just off the street where an NPU Field Technicians can manually shut off the flow of gas to the property once they arrive.  

 Q:   How often do service line breaks occur?

A:    In the last three years there has been just one uncontrolled service line break on the NPU natural gas system. This break occurred on a service line operating at or below 10 psig where EFVs would not have been used.  The last uncontrolled service line break on a service line operating over 10 psig was in 2009.

Q:    If there are so few service line breaks, why was this rule implemented?

A:    We believe that the small number of service line breaks in the NPU system is attributed to our commitment to the Connecticut Call-Before-You-Dig program that educates the public about the dangers of excavating without safely locating underground utilities.        

Q:    How does an EFV work?

A:    An EFV has a stopper disc held in place with either a spring or magnet on the inside; when a normal amount of gas flows through the EFV, gas flows around the disc, through the valve body, and to the customer’s meter.  If a break occurs in the service line, the flow of gas increases significantly which increases pressure that overcomes the forces of the spring or magnet holding the stopper disc in place. 

Q:    Will an EFV stop the flow of gas when a small gas leak occurs?

A:    No.  EFVs are designed to stop the flow of gas only when the flow of gas increases substantially.  Small leaks likely will not increase the flow of gas enough to engage the EFV device. 

Q:    Will an EFV stop the flow of gas if a leak occurs inside my house?

A:    No. An EFV will not stop the flow of gas from any leak beyond the gas regulator.  The gas regulator is usually located at or very close to the customer meter.         

Q:  If I opt to have an EFV installed on my service line will I be responsible for any future costs associated with the device?

A:    No.  Once an EFV is installed, NPU is responsible to maintain or replace it as needed.

Q:    What should I be concerned about if I have an EFV on my service line?

A:    The biggest concern customers usually have with an EFV on their service line is a ‘nuisance trip’ that can take place if additional gas appliances, such as a pool heater or an emergency generator are added to a home after the device is installed. 

        For example, a home that is simultaneously using a pool heater, a gas stove, gas clothes dryer and hot water heater may produce a load sufficient enough to unintentionally trip the EFV.  This is a rare occurrence and can be avoided by notifying NPU whenever an additional gas appliance is added to your home.

 To download a copy of this article, click here.


Electric, Sewer, Water: 860-887-2555
Natural Gas: 860-887-7207
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