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  1. #1
    Sue Roddis's Avatar
    Sue Roddis Guest

    Default Commercial building electrical requirements

    Hello, thank you in advance for your assistance today. In residential properties outlets are to be no more than 6'-0" apart. What is the minimum requirement for a commercial building with an occupancy of 45 employees?

    For example in a 10 x 12 office, how many outlets are required? As a cost savings, the landlord wants to reduce power to a 20 amp breaker per office. Does this meet code? Usually I provide at least two duplex outlets per office.

    In order to ensure tenants enough power to function succesfully, I need back-up information. Please provide (1) the applicable code & (2) a link or excerpt that I may quote.

    Thank you so very much!

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    Last edited by Sue Roddis; 08-11-2010 at 11:46 AM. Reason: additional information
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  2. #2
    Elliot Franson's Avatar
    Elliot Franson Guest

    Default Re: Commercial building electrical requirements

    Quote Originally Posted by Pamela Dorris View Post
    Hello, thank you in advance for your assistance today. In residential properties outlets are to be no more than 6'-0" apart. What is the minimum requirement for a commercial building with an occupancy of 45 employees?

    For example in a 10 x 12 office, how many outlets are required? As a cost savings, the landlord wants to reduce power to a 20 amp breaker per office. Does this meet code? Usually I provide at least two duplex outlets per office.

    In order to ensure tenants enough power to function succesfully, I need back-up information. Please provide (1) the applicable code & (2) a link or excerpt that I may quote.

    Thank you so very much!
    Ms. Dorris: I am aware of no spacing requirements for receptacles in commercial buildings save for those with residential occupancy.

    Last edited by Elliot Franson; 08-11-2010 at 02:15 PM.

  3. #3
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    Default Re: Commercial building electrical requirements

    Your post is frustratingly vague yet requesting specific citations.

    You do not detail the type of occupancy other than indicate offices and commercial (for example bank, doctors offices with patient care areas, etc.). You make reference to 45 employees but make no reference to sq. footage of the space other than to describe a 10 x 12 office to which I can safely state could not possibly have a legal occupancy load of 45 persons. You make no reference to the system design voltage.

    I suggest you first refer to the NEC. Since use, floor plan, etc. is at this point unknown, still to be considered is primary load calculations, which are then further modified by the specific occupancy.

    Load calculations, etc. are based on sq. footage to begin with. When the number of receptacles 120v are unknown one method for calculations in banks and offices is to use one VA per square foot.

    Rarely is overhead lighting in existing office space on the same circuits as 120 convienence receptacles (in fact often at different voltages - i.e. fluorescent often higher voltages, newer greener designs often lower voltage ambient lighting compact fluorescents etc. generating less heat).

    Consult with your planner and a Master Electrician or engineer to perform the calculations and develop your preliminary master plan. Your occupant and their use of space/floor plan, and your local building codes. OSHA safety requirements, etc. you cannot have cords running all over the place, etc.

    Other than residential occupancies the number of receptacles are limited per circuit based on VA limitations at 180 VA per strap. Additional considerations when utilizing pre-wired modular wall units, line conditioning requirements (interferance with computers, power supplies, etc.) copiers and laser printers on same circuits as sensitive electronics, and many others. You would need to know which loads might be continuous.

    You'll also have to accomodate cleaning crews, vacuums, floor buffers, etc. not interferring with in place office equipment.

    Additional requirements for kitchen areas, emergency lighting, signage, and many other requirements.

    You might enjoy this older article (the citations are based on older edition of the NEC) to get you started. Commercial Load Calculations

    Last edited by H.G. Watson, Sr.; 08-11-2010 at 08:20 PM.

  4. #4
    James Duffin's Avatar
    James Duffin Guest

    Default Re: Commercial building electrical requirements

    Pamela...in residential the code is 12' apart. This is so a 6' cord will reach a receptacle anywhere along the wall. In commercial you don't have to have any receptacles in a space. One thing I have seen used to get additional receptacles installed is the use of drop cords in the place of permanent wiring. The fire marshal will usually write a violation for the owner of the building if he inspects a building and finds a bunch of drop cords in use. Kind of a shady way to get a few receptacles installed but the approach works.


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