• Frequently Asked Questions

  • Where can I find information for installing electrical wiring or equipment connecting to your lines?

    We have issued an Electric Service Handbook as a general guide for our customers, contractors, architects, and engineers who are looking for requirements information. Please note that these do not replace State, County or Municipal codes and regulations.


    How do I contact my local engineering office?

    Our customers must contact us while in the planning phase of their project.

    Our numbers are listed below.


    Montgomery County

    201 West Gude Drive
    Rockville, MD 20850
    Phone: 301-670-8700
    Fax: 301-670-8718 

    Prince George’s County

    8300 Old Marlboro Pike
    Upper Marlboro, MD 20772
    Phone: 301-967-5800
    Fax: 301-967-5820  

    District of Columbia

    3400 Benning Rd. NE
    Washington, DC 20019
    Phone: 202-331-6237
    Fax: 202-388-2721 


    Do I need to contact you if I want to install emergency standby generation equipment?

    We must always be consulted before installing any electric generating equipment.


    What happens if the existing installation is unsafe?

    If the existing service installation is unsafe by our standards, you will be required to fix the situation within the time period we provide you. If the unsafe situation is not resolved, you may be disconnected.


    I want to install an IsoLATING switch, which one do I use?

    You should install an isolating switch with a visible break for all self-contained 277/480 Volt and 265/460 Volt meter installations. The customer owns and is responsible for maintaining the switch. Local Code Enforcement agencies may require a fused switch; consult with your Authority Having Jurisdiction before installing anything. This document contains approved switchgear.

    Which meter sockets and cabinets can I use?

    You can review our approved residential meter sockets list to know which standard enclosures we allow. Please recall we will not connect to any nonstandard equipment.

    I am working on drafting or designing my project, where can I get further information?

    For an in-depth look at the requirements and standards, please see the manuals for commercial and customer designs. 

    What format should my submitted electronic files be in?

    All submitted electronic files should be in a .DWG format. The drawings need to be saved back to AutoCAD 2007 or 2000 before submitting. The submitted electronic file should be Geo-referenced. Instead of basing the data on a 000 (X,Y,Z) origin point, the data should use real world coordinates, NAD 1983 HARN UTM ZONE 18N for Maryland and NAD 1983 HARN UTM ZONE 19 for the District of Columbia. You will also need to state what NAD system they are using, NAD 83 State Plane. 

    Which type of vaults can we use?

    Transformer vaults may contain only transformers and their auxiliary equipment. Our customers’ secondary fuses, circuit breakers and our meters cannot be installed in the transformer vault. The vault is not to be used for storage and access by unqualified personnel is prohibited.