Anybody use torque specifications in their systems?

Recently I found a good deal on torque screwdrivers and I bought two. One for in lbs and another for in oz. They laid around in my shop for a few months collecting dust.

This week I got around to installing some new SPD's in my main and sub panels and in my two inverters. While doing that install, I thought I'd double check the torque on all my breakers and panel connections.

Wow! I was completely surprised by how loose the connections were when compared to the proper torque specifications. Some of this work was done by licensed electricians and some by me.

I had heard that screws loosen over time and also that copper and aluminum will compress and should be double checked periodically.

Just wondering if you guys periodically check your torque and if so, how often?
18.2kW Kyocera panels; 2 Fronius 7.5kW inverters; Nyle hot water; Steffes ETS; Great Lakes RO; Generac 10kW w/ATS, TED Pro System monitoring with PVOutput.org

Comments

  • inetdoginetdog Posts: 3,123Solar Expert ✭✭✭✭
    Re: Anybody use torque specifications in their systems?
    DanS26 wrote: »
    Just wondering if you guys periodically check your torque and if so, how often?
    Just a cautionary note: Some types of fasteners and wire terminations are designed to be used with a specified initial torque and do not rely on that torque being maintained for proper operation. Some of the terminations that deform the wire fall into this category.
    By periodically re-tightening such a device to the initial torque specification you may in fact be damaging the integrity of the connection.
    It is hard to tell whether some fittings were under-torqued initially or have just "relaxed" normally with time.
    Other fittings, such as simple ring terminals on threaded studs, need the torque value to be maintained.
    SMA SB 3000, old BP panels.
  • DanS26DanS26 Posts: 235Solar Expert ✭✭✭
    Re: Anybody use torque specifications in their systems?
    inetdog wrote: »
    Just a cautionary note: Some types of fasteners and wire terminations are designed to be used with a specified initial torque and do not rely on that torque being maintained for proper operation. Some of the terminations that deform the wire fall into this category.
    By periodically re-tightening such a device to the initial torque specification you may in fact be damaging the integrity of the connection.
    It is hard to tell whether some fittings were under-torqued initially or have just "relaxed" normally with time.
    Other fittings, such as simple ring terminals on threaded studs, need the torque value to be maintained.

    Yes I was aware of this and backed off to 80% on all copper wire connections, more for for Al, but some connectors were so loose a small tug would disconnect.

    A little common sense goes a long way. I monitor the heat on continuous current connections....they are the ones I am concerned with.

    Loose connections seem to be a big problem, if not the #1 problem in home wiring.
    18.2kW Kyocera panels; 2 Fronius 7.5kW inverters; Nyle hot water; Steffes ETS; Great Lakes RO; Generac 10kW w/ATS, TED Pro System monitoring with PVOutput.org
  • inetdoginetdog Posts: 3,123Solar Expert ✭✭✭✭
    Re: Anybody use torque specifications in their systems?
    DanS26 wrote: »
    Loose connections seem to be a big problem, if not the #1 problem in home wiring.
    Totally true. A very large percentage of the fires start from "glowing connections" and neither AC nor DC arc fault sensors will detect them.
    Heat scan is a really good tool to apply regularly.
    SMA SB 3000, old BP panels.
  • DanS26DanS26 Posts: 235Solar Expert ✭✭✭
    Re: Anybody use torque specifications in their systems?
    inetdog wrote: »
    Totally true. A very large percentage of the fires start from "glowing connections" and neither AC nor DC arc fault sensors will detect them.
    Heat scan is a really good tool to apply regularly.

    I use a heat sensor tool very similar to this....not that expensive but very good in tracking down hot (or cold) spots anywhere.

    http://www.amazon.com/BAFX-Products-TM-Infrared-Thermometer/dp/B006V4WNYU/ref=pd_sim_hi_4?ie=UTF8&refRID=18C6HV2RPWJWDA8514SD

    A good tool every DIY'er should have. Also good for tracking down leaks in HVAC systems.
    18.2kW Kyocera panels; 2 Fronius 7.5kW inverters; Nyle hot water; Steffes ETS; Great Lakes RO; Generac 10kW w/ATS, TED Pro System monitoring with PVOutput.org
  • Iceni JohnIceni John Posts: 102Solar Expert ✭✭
    Re: Anybody use torque specifications in their systems?
    inetdog wrote: »
    Just a cautionary note: Some types of fasteners and wire terminations are designed to be used with a specified initial torque and do not rely on that torque being maintained for proper operation. Some of the terminations that deform the wire fall into this category.
    By periodically re-tightening such a device to the initial torque specification you may in fact be damaging the integrity of the connection.
    It is hard to tell whether some fittings were under-torqued initially or have just "relaxed" normally with time.
    Other fittings, such as simple ring terminals on threaded studs, need the torque value to be maintained.
    Is it a good idea then to use split washers, or even Belleville-type washers such as used in constant-torque hose clamps? Or is that overkill?

    I'm setting up a big (by RV standards) PV system in my bus, and I definitely don't want problems caused by vibration from driving, such as connections loosening up over time. I do use my IR temperature gun to check heavy loads' connections, such as for the starting batteries (I have a 42MT starter that can produce up to 10 HP!), but it would be a major task to check each and every connection on a regular basis.

    John

    40' Crown bus with 2kW of panels on the roof:

    Eight tiltable Sharp 255W, two Morningstar TS-MPPT-60, Magnum MS2000, Champion C46540 generator converted to propane, eight golfcart batteries eventually, and maybe a smaller inverter for the fridger.

    Southern California

  • inetdoginetdog Posts: 3,123Solar Expert ✭✭✭✭
    Re: Anybody use torque specifications in their systems?
    Iceni John wrote: »
    Is it a good idea then to use split washers, or even Belleville-type washers such as used in constant-torque hose clamps? Or is that overkill?
    A lot depends on the nature of the connection in question.
    If the connection cycles over a wide range of temperature, and especially if there are two or more different metals with different coefficients of expansion, or if the connection carries a lot of current, then use of Belleville washeres may be desirable. But since they are generally steel, you may introduce a corrosion problem. :(
    SMA SB 3000, old BP panels.
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