Forums » Electrical Engineering

equipotential bond grid

    • 4 posts
    March 13, 2019 2:40 PM PDT

    Is it "OK" to connect the equipotential bond grid to the main ground buss in the service panel? I say NO, electrician on job site says it must, and inspector passed it!

    • 200 posts
    March 13, 2019 3:28 PM PDT
    Thanks for the suggestion of this topic.

    This is a preliminary answer: at the time of 2011 NEC & 2014 NFPA, an Underwriters Laboratories (UL) proposal as follow:

    10. New UL 96A Proposal - Addition of Paragraph 10.4.4

    RATIONALE
    Paragraph 10.4.4 proposed to be added to accommodate compliance to changes in NFPA 70

    PROPOSAL
    10.4.4 If utility services are grounded to a common bus bar, then common (equipotential) bonding shall be accomplished by attaching a main size conductor to that bus bar with an appropriately sized bonding fitting.

    I am writing this in an Android, to attend your urgency, I can check later if 2018 NEC has this proposal accepted. If so the Eletrician on job is right: it MUST.

    However I am not sure about it. Please forgive me if I couldn't understand your question correctly.
    • 148 posts
    March 13, 2019 4:07 PM PDT

    It is allowed however, it is not necessary.  The equipotential bonding needs to connect all metal parts of the pool together.  If the pool pump is double insulated then you must connect the equipotential bonding to the equipment grounding conductor of the pump.

     

    680.26(B) Bonded Parts. The parts specified in 680.26(B)(1)
    through (B)(7) shall be bonded together using solid copper
    conductors, insulated covered, or bare, not smaller than
    8 AWG or with rigid metal conduit of brass or other identified
    corrosion-resistant metal. Connections to bonded parts shall be
    made in accordance with 250.8. An 8 AWG or larger solid
    copper bonding conductor provided to reduce voltage gradients
    in the pool area shall not be required to be extended or
    attached to remote panelboards, service equipment, or electrodes.

     

     

     

    680.26(B)(6) Electrical Equipment. Metal parts of electrical equipment
    associated with the pool water circulating system, including
    pump motors and metal parts of equipment associated with
    pool covers, including electric motors, shall be bonded.
    Exception: Metal parts of listed equipment incorporating an approved
    system of double insulation shall not be bonded.
    (a) Double-Insulated Water Pump Motors. Where a doubleinsulated
    water pump motor is installed under the provisions of
    this rule, a solid 8 AWG copper conductor of sufficient length
    to make a bonding connection to a replacement motor shall be
    extended from the bonding grid to an accessible point in the
    vicinity of the pool pump motor. Where there is no connection
    between the swimming pool bonding grid and the equipment
    grounding system for the premises, this bonding conductor
    shall be connected to the equipment grounding conductor of
    the motor circuit.

    • 200 posts
    March 13, 2019 4:38 PM PDT
    Dennis,

    Pool, Pool pump. Are you saying it is the same reply of other topic about "swimming pool" and 6-feet away receptacles....

    Is it the same application. For this topic here NEC 250 Chapter could or shall be applied?
    • 148 posts
    March 14, 2019 3:05 AM PDT

    I have only heard the term equipotential bonding in relation to pools.  Section 680.26 is all about the equipotential bonding of pools.  6 feet away is in relation to pool pump receptacles, if any, or other receptacles.  

     

    The equipotential bonding must bond all pool equipment no matter what distance the equipment is from the pool itself.  Metal parts not associated with the pool such as fencing etc must be bonded if they are within 5' of the pool.  

     

     


    This post was edited by Dennis Alwon at March 14, 2019 3:11 AM PDT
    • 200 posts
    March 14, 2019 3:26 AM PDT
    Ok. If I could remember correctly, we discuss that years ago on Z4I: equipotential bonding of metallic parts in and around power transmission towers and power stations (fences). But I can't recollect if we got to a conclusion at that time.

    Thanks anyway. If Mustafa is also involved with swimming pools installation is quite a coincidence. Unfortunately I can't help him by now, after a "bomb" storm we are under power shortage and phase instability. For precaution servers were shut down , can't access database, still on Android.

    I hope someone else could help him.

    • 37 posts
    March 14, 2019 4:04 AM PDT

    The following parts require bonding:

    Reinforcing metal of the pool shell, coping stones and deck
    Perimeter surfaces by bonding to the reinforcing steel of the pool at a minimum of 4 points uniformly spaced
    around the perimeter of the pool
    Metal conduits, metal door frames and metal window frames within five feet of the inside pool wall
    Metal forming shells and mounting brackets of lighting fixtures
    Metal items and fittings for hand rails, ladders, metal drains and diving boards
    Metal casings of electrical equipment such as pump motors, pool water heaters and equipment associated with
    pool covers
    Fixed metal parts within 5’ horizontally and 12’ vertically of water’s edge

  • March 15, 2019 12:52 PM PDT
    Mustafa Fadi said:

    Is it "OK" to connect the equipotential bond grid to the main ground buss in the service panel? I say NO, electrician on job site says it must, and inspector passed it!

    Tell us the rest of the story.  We need some context.

    Is this a substation?

    Agricultural building (livestock)?

    As swimming pool?

    Or something else?

    Unless you tell us, we are just guessing.

    • 4 posts
    March 15, 2019 1:15 PM PDT

    Thank you everyone. 

    @Carl Coulter: it is swimming pool.

    • 3 posts
    March 16, 2019 2:29 AM PDT

     an equipotential bonding grid is required whether a paved surface is installed or not, and applies to any permanent pool, inground or aboveground

    Photo source: Illustrated Code Changes 2008


    This post was edited by Steinberg James at March 16, 2019 2:29 AM PDT