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Thread: SPD to protect GFCIs

  1. #11
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    Quote Originally Posted by LarryFine View Post
    Not exactly; it shouldn't share a breaker. The SPD doesn't draw 20a, that's just the size breaker that should be used.
    What is the exact reason it shouldn't share a breaker?



    Nope, all of them. Parallel is parallel.

  2. #12
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    Quote Originally Posted by tersh View Post
    What is the exact reason it shouldn't share a breaker?
    First, the breaker may not be rated for more than one conductor per terminal. Second, a defective circuit would disable a shared breaker, removing the protection. Third, product instructions should be followed.
    Code references based on 2005 NEC
    Larry B. Fine
    Master Electrician
    Electrical Contractor
    Richmond, VA

  3. #13
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    Quote Originally Posted by tersh View Post
    To vendors, electricians, engineers,

    For a house with 10 GFCI receptacles, they would be useless if the GFCIs got fried by external surges. The internal MOV (Metal Oxide Varistors) in each is not enough. They are good for only a few years then the GFCI circuit become vulnerable to damage.

    Now consider this Siemens whole house 140,000A surge current SPD (Surge Protector Device) with data sheet at:

    https://www.downloads.siemens.com/do...id1=BTLV_43434

    available at amazon https://www.amazon.com/gp/product/B0...k_ql_qh_dp_hza





    The wires are only size #10 AWG and it requires 20A breaker.

    What would happen if this is connected to the main breaker of say 100A instead of buying 16 pieces and connecting to each 20A breaker.

    Note it is not an appliance. It doesn't conduct at normal voltage. Only when it reaches above the threshold voltage (MCOV rating) that it begins to conduct and do the voltage divider impedance action thing. But notice that this voltage divider action is only for the surges, not the normal 100A current.

    So my question is whether Siemens requiring it to put on each 20A breaker and buy 16 pieces is just sales gimmick instead of buying just one to put on the main 100A breaker.

    Can the 100A regular current really passes through the Siemens SPD when the SPD only conducts at higher voltage during actual surges. Even then, the voltage divider action is for only for the surge current and not the regular 100A, is it?

    Btw.. let's not confuse the 140,000A surge current rating which is the capacity of the Surge current the SPD can handle, not the regular current (note too that Siemens knows their #10 awg can handle 140,000A surge current because it is not continuous.. so what's wrong putting it in 100A breaker instead of buying 16 pieces for each 20A breakers?).

    If you want to protect all the 10 GFCI receptacles at the house, what kind of main breaker SPD do you usually use? Do you really need the SPD to have #2 AWG wire. Notice an SPD is not normal load or appliance so why does the wiring have to match the regular wiring and ampere table?
    The device, when it's in the on position, is looking at the Entire Busbar/s. Which means it is protecting all circuits from a surge. They have the high capacity MOV's to protect a high inrush. The whole house should be protected. At that price, it should be!

    Living here in Florida, I believe they are worthless. Just fix the stuff that breaks, or as it breaks because of lightning.

  4. #14
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    Quote Originally Posted by LarryFine View Post
    First, the breaker may not be rated for more than one conductor per terminal. Second, a defective circuit would disable a shared breaker, removing the protection. Third, product instructions should be followed.
    Ok. Got it. Thanks.

    If the Siemens Whole House SPD would be put in a subpanel, can it protect the main panel and the entire house too? Or just the subpanel? Or is there a distance threshold where putting the SPD in subpanel can still protect the main panel or not?

    For example. Putting the subpanel one meter away from main panel can protect the whole house, whole anything more than 2 meters away won't. Any rule for this?

  5. #15
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    Quote Originally Posted by tersh View Post
    Ok. Got it. Thanks.

    If the Siemens Whole House SPD would be put in a subpanel, can it protect the main panel and the entire house too? Or just the subpanel? Or is there a distance threshold where putting the SPD in subpanel can still protect the main panel or not?

    For example. Putting the subpanel one meter away from main panel can protect the whole house, whole anything more than 2 meters away won't. Any rule for this?
    Your adding length to the circuit. Its spec is based on the length of the wires that are coming out of the unit to the breaker/Buss. If you look at the spec, it says 1 nanosecond response time. You would be adding time to this if it was in the sub panel and you are trying to protect the main panel. It still might work but the time has been lengthened which is the whole point of this thing.

    I'm sure someone will correct me if I'm wrong. It sounds like you need two to do the job correctly. At least that is what Siemens would say.

  6. #16
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    Quote Originally Posted by tersh View Post
    If the Siemens Whole House SPD would be put in a subpanel, can it protect the main panel and the entire house too?

    Any rule for this?
    There is no threshold figure, but the closer to the main breaker, the better. The shortest pathway is to install the SPD's breaker in the 1-3 or 2-4 position, and the neutral and/or EGC wires should be shortened and run in the straightest line to the respective bus(es) with as few bends as possible.

    If you want to protect everything, put it in the main panel. If you want superior protection for circuits fed from the sub-panel, put one in each panel. If you want maximum protection for particular equipment, like computer or home-theater systems, cascade protection by combining panel-mounted and point-of-use protective devices.

    Whole-house protection works best to protect against surges from outside the premises, while point-of-use protection works to protect specific equipment from surges generated within the premises. Generally, I would recommend an SPD in the main panel and one at the sensitive point of use.
    Code references based on 2005 NEC
    Larry B. Fine
    Master Electrician
    Electrical Contractor
    Richmond, VA

  7. #17
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    Quote Originally Posted by tersh View Post
    If it's connected to an existing 30A breaker that supplies other wires and load, and the ampere of the load is only 10A or less, the Siemens connected to it would still protect the load in that shared breaker.. isn't it?

    No problem reserving a dedicated breaker to it. I thought the past 6 months it only protects the breaker it is connected too.
    Nope. It is not to be connected on another loads breaker. It is supposed to be connected on its own breaker as the only load. If you do not have enough space on your panel you cannot put it on your panel. Do not think of it as something that can be added to a current circuit, or such. It does a job just like a dishwasher does a job, but it is easier to think of it as an appliance that does not leave the breaker panel in some cases, and does nothing until it is needed.
    It gets connected only to the breaker size that Siemens wants it at, which is 20 amp. On its own. As the Manufacturer specifies. Any other use of it, like putting on a 30 amp breaker with something else, is against the manufacturers directions and so violates the NEC.
    Student of electrical codes. Please Take others advice first.

  8. #18
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    From the first draft report for the 2020 code.
    230.67 Surge Protection.

    (A) Surge Protective Device.
    All services in dwelling units shall be provided with a surge protective device (SPD).



    (B) Location.
    The surge protective device shall be an integral part of the service equipment or shall be located immediately adjacent thereto.
    Exception: The surge protective device shall not be required to be located in the service equipment as required in (B) if located at each next level distribution equipment downstream toward the load.




    (C) Type.
    The surge protective device shall be a Type 1 or Type 2 SPD.



    (D) Replacement.
    Where service equipment is replaced, all of the requirements of this section shall apply.
    From the substantiation for the PI that resulted in 230.67.
    Electronic life saving equipment such as fire alarm systems, IDCI’s, GFCI’s, AFCI’s and smoke alarms, may be damaged when a surge occurs due to lighting, internal local switching as well as external utility switching. Other equipment is also damaged when subjected to surge. In many cases, electronic devices and equipment can be damaged and rendered inoperable by a surge and yet this damage is undetected by the owner. It is practical to require a SPD to provide a general level of protection. In almost all new service installations, as well as service upgrades, no consideration is given to providing a general level of protection to the “whole structure” which would include those devices that cannot be afforded a cord connected Type 3 SPD protection. First level subdivision (D) is included to require that when a service is upgraded, an SPD is to be installed. For example, in 2002, the product standard for GFCI’s was revised due to documented failures of devices that were occurred when the devices were subjected to transients. The fact that the electrical industry redesigned GFCI technology to address well documented damage to these life saving devices is reason enough to require whole house/structure SPD protection. The changes that were made do not prevent the GFCI from being damaged but rather provide a requirement for these devices to self-test and determine if they were damaged and are no longer functioning properly. Studies by recognized authorities including NEMA, IEEE, and UL, all substantiate the fact that surges can and do cause significant damage. Nationwide Insurance organizations recognize the need for effective surge protection as well and have published recommendations that include point-of-use surge protectors and installation of surge protection at service equipment. The NEC must mandate a minimum requirement for surge protection in all services. It is “practical” to provide this minimum and feasible level of protection for all electronic life saving devices already mandated within the NEC. See Section 90.1 of the NEC.
    Don, Illinois
    (All code citations are 2017 unless otherwise noted)

  9. #19
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    Here we go again! Design the damn devices properly so they are resistant to damage from surges or indicate when they are damaged, don't create another "golden egg" for manufacturers.

    -Hal

  10. #20
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    Quote Originally Posted by hbiss View Post
    Here we go again! Design the damn devices properly so they are resistant to damage from surges or indicate when they are damaged, don't create another "golden egg" for manufacturers.

    -Hal

    The insurance companies are ruling the roost here.

    Hmm, OK, when the thing blows off the wall during a lightning strike, who do I sue to say the device failed?

    Good luck, manufacturers. You know they will have a sticker saying that they cannot guarantee the device from not failing from acts of God. So what good is it? My 2 cents. I guess the AFCI has already saturated the market. We need some new revenue streams...

    I'm normally not a cynical person. But this is the insurance companies and manufactures sticking it to the poor homeowner.

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