Quick ? -- Ground new pole mount array at pole or at power shed 50 feet away?

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  • PorkChopsMmmPorkChopsMmm Solar Expert Posts: 189 ✭✭✭✭✭
    Re: Quick ? -- Ground new pole mount array at pole or at power shed 50 feet away?

    I buried the #6 bare solid copper from the new ground rod at the base of the array to the ground rod at the power barn 35 feet away. Now that that is done, what gauge wire do you recommend for linking up the panels, array, pole, etc. to the ground pole at the base of the array? I have seen anywhere from 10 gauge to 6 gauge. Looking for your opinion before I spend the addition $60 on #6 wire.
  • BB.BB. Super Moderators, Administrators Posts: 28,176 admin
    Re: Quick ? -- Ground new pole mount array at pole or at power shed 50 feet away?

    Decades ago, we could use 8 awg insulated or 6 awg wire for grounding the AC panel in a home (something like 125 amp service if I recall correctly)--Not sure today what NEC says.

    6 AWG is generally recommended just because it is a heavier cable and less likely to be damaged/broken when connected to ground rods and/or direct buried in the earth.

    From a short circuit point of view, you want to cable to be heavy enough/low enough resistance to carry any short circuit current...

    Very roughly, 6 awg fusing current is ~600 amps... So if you are looking at currents over ~100-200 amps, you probably want a heavier grounding cable. Also, for very long cable runs, you want the over all resistance of the wiring low enough to kick the breaker--You don't want 120 VAC at 15 amps (or whatever) to be just heating the cable because of too high of voltage drop (i.e., very long small diameter cables may not allow enough current to flow and quickly trip the protective breaker/fuse).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • PorkChopsMmmPorkChopsMmm Solar Expert Posts: 189 ✭✭✭✭✭
    Re: Quick ? -- Ground new pole mount array at pole or at power shed 50 feet away?

    #6 it is. My array is on a pole and can tilt/rotate. I was going to leave some slack in there so that there is no pressure when rotating or tilting the array. Would solid #6 be better for that or stranded?

    Thanks for the help!
  • BB.BB. Super Moderators, Administrators Posts: 28,176 admin
    Re: Quick ? -- Ground new pole mount array at pole or at power shed 50 feet away?

    Regarding using the 1 amp fuse for DC GFI... I would guess that all Midnite charge controllers are monitoring the DC ground to Safety ground voltages--So, if the 1 amp fuse (or a breaker) were to open, then the non-zero voltage between DC return and safety ground would force all MPPT charge controllers to shut down.

    For Midnite MPPT charge controllers, many (some models, all models, I don't know) have Arc Fault detection. This is a much better form of protection (the controller monitors for RF frequencies associated with Arcing Connections and shuts down if any are detected).

    The original DC GFI was designed to reduce the chances of Arc Faults--And the DC GFI was a cheap and dirty way of "doing something".

    In my humble opinion, DC GFI should be disabled by hard grounding the DC Return to Safety Ground. The (very minor) protection against DC power to earth faults is not worth the many problems that are caused by installing a 1 amp fuse between safety ground and earth ground.

    Ryan "halfcrazy" from Midnite (and a frequent poster here) said:

    In terms of the classic hardware, I'm reading this as

    if I tie my ground bus to negative bus, it will defeat the gfp capability of the classic since the classic won't be able to detect voltage differences between ground and (-). Is that correct? Other than that, there is no impact to the classic. Is that also correct?
    That is correct. And is most likely how you would find my system with a big fat wire connecting battery negative and earth ground.

    And Robin (also from Midnite) in the post below:
    We all at Midnite agree that the DC-GFP is dangerous. We will very soon, publish a paper on our website using some of Bills and our arguements against the DC-GFP system. The DC-GFP per NEC was ok back in the early 90's. As boB stated, it was too expensive to manufacture. boB designed the only DC-GFP in existence that broke both the positive and negative PV legs and also shorted the PV array. We did we do that at Trace? Because that was the way the NEC required it to be done! When John Wiles came up with the present method that EVERYBODY uses, it made the system affordable. Back then all we had was 48 volts. There was no such thing as grid tie inverters or high voltage MPPT charge controllers. 48V was not a lethal voltage. Our big beef is that DC-GFP's don't actually do much to stop fires. Arc fault detectors do however. We think it is time to eliminate the DC-GFP from the NEC and start enforcing the arc fault protection system. We have been shipping the world's only DC arc fault protector in the Classic for over a year now. Funny how the industry is hung up on getting the DC-GFP correct, but doesn't give the arc fault protector a second thought. I personally wouldn't install a DC-GFP in a system over 48 volts, but I certainly would install an arc fault protector. They really do stop fires. As a manufacturer, we can't tell people to ignore the NEC even if it may kill you. Yah right! We will campaign to get the DC-GFP thrown out of the NEC.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • EdwardoEdwardo Registered Users Posts: 16
    Re: Quick ? -- Ground new pole mount array at pole or at power shed 50 feet away?

    I'm not sure if this is relevant...but when we build high voltage power lines we are required to ground every fifth pole which works out to about 280m-300m between grounds.The ground rods/plates are all tied into the system neutral.
  • BB.BB. Super Moderators, Administrators Posts: 28,176 admin
    Re: Quick ? -- Ground new pole mount array at pole or at power shed 50 feet away?

    Very interesting--What is the working line voltage of those towers?

    I am evolving on my thoughts regarding multi-point AC Neutral to Earth grounding when working with power distributed outside a single home/smallish building. Especially in lightning prone areas (multi-point bonding/earth grounding is a good thing with lightning). There is always the question of "voltage gradients" from strikes (put two ground rods a 100 feet apart and you can get thousands of volts difference between them--depending on where the strike occurs).

    Lightning energy does not travel very far in cabling (something like 10's of feet). So, I wonder how much energy can actually be injected in a ground (or neutral) bond between to ground rods a fair distance apart.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • vtmapsvtmaps Solar Expert Posts: 3,738 ✭✭✭✭
    Re: Quick ? -- Ground new pole mount array at pole or at power shed 50 feet away?
    BB. wrote: »
    For Midnite MPPT charge controllers, many (some models, all models, I don't know) have Arc Fault detection. This is a much better form of protection (the controller monitors for RF frequencies associated with Arcing Connections and shuts down if any are detected).

    It works for series arc faults. It does not work for parallel arc faults (between hot and neutral or hot and ground). The GFP does work for parallel arc faults between Hot and ground, but as you have indicated it has serious safety issues when tripped.

    I think a better solution is an arc fault combiner. It will disconnect the panels for series or parallel arc faults.

    --vtMaps
    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
  • BB.BB. Super Moderators, Administrators Posts: 28,176 admin
    Re: Quick ? -- Ground new pole mount array at pole or at power shed 50 feet away?

    Yep--Having slave trip breakers back at the source of power (solar array) is a better solution.

    However--Because DC does not have any "natural" isolation like AC circuits do (i.e., power transformers). So any attempts to isolate shorts/faults at the DC System level through "simple" means (or even arc fault sensing) will be problematic with false trips and/or difficult to isolate faults (vs shutting everything down and having to bring the system up "piece by piece").

    Much of this goes back to solar panels and the fact they are current sources and fuses/breakers are pretty useless to protect against many types of short circuits.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • EdwardoEdwardo Registered Users Posts: 16
    Re: Quick ? -- Ground new pole mount array at pole or at power shed 50 feet away?

    The lines I build are 15kv,we install lightning arrestors on each transformer.
  • YehoshuaAgapaoYehoshuaAgapao Solar Expert Posts: 280 ✭✭
    Re: Quick ? -- Ground new pole mount array at pole or at power shed 50 feet away?
    BB. wrote: »
    And Robin (also from Midnite) in the post below:

    We all at Midnite agree that the DC-GFP is dangerous. We will very soon, publish a paper on our website using some of Bills and our arguements against the DC-GFP system. The DC-GFP per NEC was ok back in the early 90's. As boB stated, it was too expensive to manufacture. boB designed the only DC-GFP in existence that broke both the positive and negative PV legs and also shorted the PV array. We did we do that at Trace? Because that was the way the NEC required it to be done! When John Wiles came up with the present method that EVERYBODY uses, it made the system affordable. Back then all we had was 48 volts. There was no such thing as grid tie inverters or high voltage MPPT charge controllers. 48V was not a lethal voltage. Our big beef is that DC-GFP's don't actually do much to stop fires. Arc fault detectors do however. We think it is time to eliminate the DC-GFP from the NEC and start enforcing the arc fault protection system. We have been shipping the world's only DC arc fault protector in the Classic for over a year now. Funny how the industry is hung up on getting the DC-GFP correct, but doesn't give the arc fault protector a second thought. I personally wouldn't install a DC-GFP in a system over 48 volts, but I certainly would install an arc fault protector. They really do stop fires. As a manufacturer, we can't tell people to ignore the NEC even if it may kill you. Yah right! We will campaign to get the DC-GFP thrown out of the NEC.

    Does this mean that the Xantrex 150V MPPT charge controllers do the GFP the correct way or were they done the easy John Wiles way since these were probably put out after Xantrex bought out Trace (Surely wouldn't trust Schneider to make anything better)?

    If the GFP were disabled and it grounded the old school way, you would need to run a 4/0 from the battery negative (or battery negative bus) to the ground rod?

    Any way to get arc-fault protection using no more than 2 breaker slots in the combiner box at a reasonable cost? Don't arc-fault interrupters get a lot of false/nuisance trips? Would arc-fault protectors in the combiner boxes cover the post-charge controller DC side at all?
  • BB.BB. Super Moderators, Administrators Posts: 28,176 admin
    Re: Quick ? -- Ground new pole mount array at pole or at power shed 50 feet away?
    Does this mean that the Xantrex 150V MPPT charge controllers do the GFP the correct way or were they done the easy John Wiles way since these were probably put out after Xantrex bought out Trace (Surely wouldn't trust Schneider to make anything better)?

    In my humble opinion, there is no "right way" to implement DC GFI using a ~1 amp fuse/breaker between Battery Return and Safety Ground. This is just a cheap and dirty way of trying to detect Hot to Ground current flow (1 amp fuse pops, breaker opens, etc.). If this was an AC system, it would be done with with a simple current transformer on the +/- power leads that could easily detect leakage current (unequal current flow in +/- power leads) down to ~5-10 milliamps like is done with AC GFI systems.

    Dave Sparks, an installer here with lots of Xantrex and Lightning experience in the Mountains of California is very happy with the Xantrex implementation and the shutting down of the XW MPPT Charge controller if the DC GFI fuse pops (as I understand, he believes shutting down the XW MPPT controller makes it more lightning/failure resistant).

    Take your pick... I don't have the lightning experience so I have to differ to Dave that this has been working out for his installations/customers (as I recall, not trying to speak for Dave).
    If the GFP were disabled and it grounded the old school way, you would need to run a 4/0 from the battery negative (or battery negative bus) to the ground rod?

    The ground rod does not carry much current (a hand full of amps at 48 volts--lightning is a different issue).

    The 4/O cable would be if you were (for example) grounding the chassis of a large AC inverter back to the ground rod (with a 4/O cable) and running back to the battery return bus ground with another 4/O cable (in NEC, they sometimes allow a slightly smaller ground return cable--The ground path only needs to carry enough current for a limited time to pop the breaker/fuse on the 4/O hot cable connection--such as a short from Hot to Chassis in the inverter).

    You could run the Green Wire safety ground to the Battery Return or to the Ground Rod and back to the Battery Return... Sort of like the Neutral+Earth Bond is actually made inside the Main AC panel... We don't run the Neutral from the neutral bus to the AC ground rod separate from the Green Wire Ground bus (Neutral and Safety Ground bus are identical in the Main Panel--In sub panels, the Neutral and Safety Ground bus are separate to keep the Neutral floating).
    Any way to get arc-fault protection using no more than 2 breaker slots in the combiner box at a reasonable cost? Don't arc-fault interrupters get a lot of false/nuisance trips? Would arc-fault protectors in the combiner boxes cover the post-charge controller DC side at all?

    I believe Midnite has been working on a DC Arc Fault system (outside of the Classic MPPT charge controllers)--But I don't know anymore than that...

    Arc Fault breakers for AC systems have been known for false trips (universal-brush type motors have some arcing on the commutator which can confuse an Arc Fault breaker).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • YehoshuaAgapaoYehoshuaAgapao Solar Expert Posts: 280 ✭✭
    Re: Quick ? -- Ground new pole mount array at pole or at power shed 50 feet away?
    BB wrote:
    We got a rabbit a couple years ago--My power cords for the power bricks--Have a bunch of repairs and tape now. He seems to mostly like the DC side.

    Any idea why the "bad luck" with your power supplies/refrigerator? AC surges from near by lightning strikes... Could also be line voltages running high or low. Even a bad neutral (corroded neutral block--Mine was damaged by a water leak from rain) can cause issues (120 to neutral will go 240 to "neutral" if the neutral connection fails at the wiring block.). If you see some lights "brightening" when a refrigerator or other heavy 120 VAC load starts, could be neutral connection starting to fail somewhere.
    Don't know. Did put a start capacitor in the AC in 2010 but not for electrical problem reasons. AC Guy sold it to me saying that since it is over 10 years old, a start capacitor will delay its eventual failure. No light flickering problems other than when the generator exercises and the inverter switches to it to exercise it under load. I had the inverter disconnect from the grid without the grid going out in the late evening twice - once in March and once in April. Hasn't occurred since. There were no faults logged though.

    Don't know. Did put a start capacitor in the AC in 2010 but not for electrical problem reasons. AC Guy sold it to me saying that since it is over 10 years old, a start capacitor will delay its eventual failure. No light flickering problems other than when the generator exercises and the inverter switches to it to exercise it under load. I had the inverter disconnect from the grid without the grid going out in the late evening twice - once in March and once in April. Hasn't occurred since. There were no faults logged though.

    I do get a lot of overfrequency anti-islanding faults. In April and may was getting one or two every day. Getting about 2-4 per week in July. Fault always clears when the 300 second reconnect timer runs out. Could be measurement inaccuracy - maybe a badly distorted wavelength being measured as multiple. Can't really tell. Grid voltage is usually steady between 122 and 124V (once in a while it gets to 125V for a short time). The AC running reduces grid voltage (measured by inverter AC1) by about 1-1.5V (more 1.5 at night) but is otherwise stable.

    The only thing I see that is weird, is when AC1 (grid) is disconnected but still 'up' and the generator is running and AC2 (gen) is connected, AC2 and AC-out voltage are steady but AC1 (Grid) starts fluctuating between 119 and 124V in about 15 second intervals. This is only when AC1 is disconnected but the grid is still up.

    The other issue is that the L2 current measured at AC-out (subpane loads) is sometimes reads too low - Volt*Amps < Watts, like a >100% power factor. There is no negating opposite on L1 though (AC-out).

    Any insights on this?

    Some more details:
    The motor on one of my swamp coolers (the one in the garage) seized up in April, tripping the GFCI trying to start. It was plugged into an outlet that is on the subpanel L1 (It was used prior to solar installation also). It was under warranty, but the are otherwise $200 to replace. This is the only thing electrical that died after the solar was installed. This may or may not be electrical related.

    The refrigerator died September of last year (Sep 2012), before any solar was installed. It had two compressors, the refrigerator side failed, the freezer side was still working fine. The replacement fridge is a lot more energy efficient (energy star)

    The dying power bricks are all Dell (laptop) or ByteCC (hard drive enclosure). Haven't had a HP (laptop) or Rosewill (dual-bay hard drive enclosure) power supply fail yet. The ByteCC power bricks live only 1-2 years while the Dells live only 2-3 years. Only have one dell laptop left, it is not really used anymore. Have one ByteCC enclosures in service, hooked up to the dish network DVR. The HP DV8t is 3 years old and one of the HP Mini 311s are also 3 years old nothing fried yet.

    I've had two LED night lights burn up, both prior to the solar installation. No fire, but burning smell, black. LED night lights do not have a grounded plug and they are not plugged into a surge protector.

    For the L2 on the subpanel showing higher watts than volts*amps (>100% power factor), L2 has a lot of DC power bricks on it. 4 external hard drives (internal power supply), 4 USB hubs, router, ethernet hub, 1 laptop, 3 netbooks (linux play machine, computer for the bedroom, file sharing / weather station / magicjack machine), printer (internal power brick), 3 LED TVs (internal power supply), and two USB gadget charging stations. These would lend itself to a lower power factor. Not sure why it would get the watts right and the amps wrong (clamp meter shows the watts are more correct than the amps). I believe some DC power supplies tend to only draw near the crest of the sine wave. You think this could contribute to what I'm seeing?

    I know the house ground still works on the subpanel with the solar installation. Dogs (one of Shawn's dogs, lot less disciplined) chasing cat, cat pees on power strip in fear of its life, sparks, family room breaker on subpanel trips. This occurred about March of this year. Hazel doesn't come over the house much anymore. This dog is also a really bad chewer and will chew soda cans and spraypaint cans, and at Shawn's house, chewed up his air conditioner power cable once (split unit).
  • YehoshuaAgapaoYehoshuaAgapao Solar Expert Posts: 280 ✭✭
    Re: Quick ? -- Ground new pole mount array at pole or at power shed 50 feet away?
    BB. wrote: »
    In my humble opinion, there is no "right way" to implement DC GFI using a ~1 amp fuse/breaker between Battery Return and Safety Ground. This is just a cheap and dirty way of trying to detect Hot to Ground current flow (1 amp fuse pops, breaker opens, etc.). If this was an AC system, it would be done with with a simple current transformer on the +/- power leads that could easily detect leakage current (unequal current flow in +/- power leads) down to ~5-10 milliamps like is done with AC GFI systems.

    Dave Sparks, an installer here with lots of Xantrex and Lightning experience in the Mountains of California is very happy with the Xantrex implementation and the shutting down of the XW MPPT Charge controller if the DC GFI fuse pops (as I understand, he believes shutting down the XW MPPT controller makes it more lightning/failure resistant).

    Take your pick... I don't have the lightning experience so I have to differ to Dave that this has been working out for his installations/customers (as I recall, not trying to speak for Dave).


    The ground rod does not carry much current (a hand full of amps at 48 volts--lightning is a different issue).

    The 4/O cable would be if you were (for example) grounding the chassis of a large AC inverter back to the ground rod (with a 4/O cable) and running back to the battery return bus ground with another 4/O cable (in NEC, they sometimes allow a slightly smaller ground return cable--The ground path only needs to carry enough current for a limited time to pop the breaker/fuse on the 4/O hot cable connection--such as a short from Hot to Chassis in the inverter).

    You could run the Green Wire safety ground to the Battery Return or to the Ground Rod and back to the Battery Return... Sort of like the Neutral+Earth Bond is actually made inside the Main AC panel... We don't run the Neutral from the neutral bus to the AC ground rod separate from the Green Wire Ground bus (Neutral and Safety Ground bus are identical in the Main Panel--In sub panels, the Neutral and Safety Ground bus are separate to keep the Neutral floating).

    I'll probably just leave it be. 2 4/0's running through the wall and the large conduits, etc.., and 4/0 ground rod connectors looks expensive for just a minor safety increase.
  • BB.BB. Super Moderators, Administrators Posts: 28,176 admin
    Re: Quick ? -- Ground new pole mount array at pole or at power shed 50 feet away?

    If you were running an MSW AC inverter--The power bricks/power supplies/refrigerator failures could be attributed to the modified square wave output of the inverter--But you are running an XW which is a true sine wave.

    Assuming you have 120/240 VAC split phase power (typical North American Home)--Your descriptions sound like either lightning/surge damage or a bad neutral connection back to the utility transformer. If you have lightning storms in your area, some surge suppressors on the AC main panel would not hurt.

    Surge--You might see it as unreliable utility power (lots of outages, perhaps some quick brightening/dimming of lighting and/or TVs/computers rebooting, etc. And if you have power strips with surge suppressors--Breaker/fuse trips on power string or panel breakers (MOV surge suppressors clamp the voltage and pop a breaker).

    Failing Neutral wiring/connection--You could have a poor/intermittent neutral connection back to pole transformer and see L1/L2 voltages vary (example: L1 goes near zero volts while L2 goes near 240 volts when neutral fails) and this would affect all circuits in the home. You could also have a neutral fail on just one Neutral (to a bed room or kitchen circuit--on a shared black/red/neutral wired connection).

    Otherwise, I don't really have a clue. You are having way more "bad luck" than I would expect. Other issues could be high humidity corroding electronics, dust, bugs attracted to heat/electronics/wiring, etc.. But all of that should be visible if you take a failed unit apart. A large A/C system with switching (inductive kick from motors) could cause local surge voltages.

    Surge voltage problems/issues are very hard to catch with logging meters--Cheap meters generally don't really do a good job of capturing such events. And you don't know if surges occur multiple times a day or just a few times a year--so they can be easy to miss. And surges/voltage excursions can weaken devices so they fail later without any surges happening at the moment. With the "death" of filament bulbs, surges are getting harder to "see". The regulation of many CFL/LED/Florescent lighting ballasts make surges less visible. Switching power supplies on TV's, radios, etc. make voltage sags/surges less obvious too. Computers will either work or reboot/power off/fail when surges happen -- or do nothing obvious. Much harder to notice a surge.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • YehoshuaAgapaoYehoshuaAgapao Solar Expert Posts: 280 ✭✭
    Re: Quick ? -- Ground new pole mount array at pole or at power shed 50 feet away?
    BB. wrote: »
    If you were running an MSW AC inverter--The power bricks/power supplies/refrigerator failures could be attributed to the modified square wave output of the inverter--But you are running an XW which is a true sine wave.

    Other than the swamp cooler motor seizing up, haven't had any power supply or appliance fail since the solar installation (about November 2012; grid-tie was commissioned February 2013 - delay was from a missing form and taking a month to notice)
    BB. wrote: »
    Assuming you have 120/240 VAC split phase power (typical North American Home)--Your descriptions sound like either lightning/surge damage or a bad neutral connection back to the utility transformer. If you have lightning storms in your area, some surge suppressors on the AC main panel would not hurt.

    Surge--You might see it as unreliable utility power (lots of outages, perhaps some quick brightening/dimming of lighting and/or TVs/computers rebooting, etc. And if you have power strips with surge suppressors--Breaker/fuse trips on power string or panel breakers (MOV surge suppressors clamp the voltage and pop a breaker).

    Failing Neutral wiring/connection--You could have a poor/intermittent neutral connection back to pole transformer and see L1/L2 voltages vary (example: L1 goes near zero volts while L2 goes near 240 volts when neutral fails) and this would affect all circuits in the home. You could also have a neutral fail on just one Neutral (to a bed room or kitchen circuit--on a shared black/red/neutral wired connection).

    I have not observed voltage swinging from 0 or 240V and the inverter would throw faults over this I believe. All 120V circuits except the laundry, fomerly-refrigerator, dishwasher, microwave, garbage disposal, and dining room (b/c of shared neutral with a kitchen circuit) are on the subpanel. These 4 circuits will be moved at expansion. No 220V circuits (A/C, Water heater / SHW backup element, range, pool pump subpanel) are moved nor will be moved.

    When first installing the system and testing the generator the generator's L2 connection caught a bit of the insulation and the voltage was swinging wildly. I was able to fix this myself as it was just re-seating a wire connection in the inverter.

    I have had the refrigerator, chest freezer, both swamp coolers, solar hot water pumps, and the netbook in the garage plugged into Belkin SurgeCubes (single-outlet, 1100 joule, 3-MOV surge protectors, $6 each) since October last year.

    Also just bought 2 Monster HTS1000-MKIII (6100 joules, stage 2 clean power) and moved older PC800 (2009, 1665 Joules, Stage 1 clean power) down the line to the master bedroom, and Printer/scanner/landline phone base/misc. Those (also PC800) 2007 strips moved on to the dish network receiver in the family room and a the charging station (a bunch of 2-port USB adapters) in the master bedroom. The yet older strips moved down the line and the two oldest monster power (they still work and show surge protection despite being 2001 and 2003) I put in Hope and Jenna's room. The Living room has 2 HP 450 (6000 joules, not clean power, most of stuff in living room are Hope's). These are not moving anywhere.
    BB. wrote: »
    Otherwise, I don't really have a clue. You are having way more "bad luck" than I would expect. Other issues could be high humidity corroding electronics, dust, bugs attracted to heat/electronics/wiring, etc.. But all of that should be visible if you take a failed unit apart. A large A/C system with switching (inductive kick from motors) could cause local surge voltages.

    Very dry in AZ except in July.

    Dust is an issue in my house. 5 full-time dogs, 2 part-time dogs (Shawn's), 6 indoor/outdoor cats (4 are kittens), 4 outdoor cats (Crystal's bullying, demanding whole house to herself makes them not want to come back in), 4 full-time humans (Me, my sister, Her boyfriend, their daughter), and 2-3 part-time humans (Shawn, his girlfriend, his best friend).

    The air conditioner has had a start capacitor (KickStart) since early 2010. There is nearly zero voltage impact when it starts up. The ByteCC single-drive enclosures were replaced by Rosewill dual-bay enclosures in early 2010. One Dell was replaced by HP in mid 2010. The 2nd dell was replaced by an HP in mid 2012. It could be just the Dell/ByteCC power supplies being defective / overheating. The only CFLs that experience early failure are those screwed into un-vented enclosures (ballast electronics overheat - usually capacitors). Actually have had a DC power brick fail since 2010.
    BB. wrote: »
    Surge voltage problems/issues are very hard to catch with logging meters--Cheap meters generally don't really do a good job of capturing such events. And you don't know if surges occur multiple times a day or just a few times a year--so they can be easy to miss. And surges/voltage excursions can weaken devices so they fail later without any surges happening at the moment. With the "death" of filament bulbs, surges are getting harder to "see". The regulation of many CFL/LED/Florescent lighting ballasts make surges less visible. Switching power supplies on TV's, radios, etc. make voltage sags/surges less obvious too. Computers will either work or reboot/power off/fail when surges happen -- or do nothing obvious. Much harder to notice a surge.

    My inverter seems to notice overfrequency events plenty of times (F25) - get a number of overfrequency anti-islanding faults. Can excessive frequency cause failures? These power bricks are all international rated though (110-230V 50-60hz). Haven't had any failures in a DC power supply since 2010 also - only the refrigerator and swamp cooler.

    I have not observed >125 volts in the XW-config or SCP at all though it probably won't display fraction-of-a-second surges or micro-surges (surges below surge protector clamping voltage).

    AC1 Sell/GridSupport/LoadShave (Not user-configurable) 105.6-132V 59.4-60.4 Hz - F23-F40
    AC1 Passthrough/Charge (configurable / left at default) 106-132V 55-65Hz - No Faults for violations, only disconnection and re-qualification
    AC2 Passthrough/Charge (configurable / left at default) 80-138V 55-65Hz - No Faults for violations, only disconnection and re-qualification
    AC-Out - 108-130V - F1-F2, voltage only - no faults for frequency

    Only have had one overvoltage fault, and it was caused by me - I shut off the main breaker to show off the system's bi-modal characteristics to an appraiser (refinancing the home equity home improvement loan into the 1st mortgage, 3.5% fixed; didn't have enough home equity in 2012, but home values increased in 2013; appraiser only added $15K to value for solar system & other improvements though). This surge was obviously for a fraction of a second so micro-surges should show up as faults on the inverter. It was an F29 and not a F30, so the voltage spike was minor (F29 is 260-270V L-L, F30 is 270+V L-L)
  • BB.BB. Super Moderators, Administrators Posts: 28,176 admin
    Re: Quick ? -- Ground new pole mount array at pole or at power shed 50 feet away?
    My inverter seems to notice overfrequency events plenty of times (F25) - get a number of overfrequency anti-islanding faults. Can excessive frequency cause failures? These power bricks are all international rated though (110-230V 50-60hz). Haven't had any failures in a DC power supply since 2010 also - only the refrigerator and swamp cooler.

    I have not observed >125 volts in the XW-config or SCP at all though it probably won't display fraction-of-a-second surges or micro-surges (surges below surge protector clamping voltage).

    AC1 Sell/GridSupport/LoadShave (Not user-configurable) 105.6-132V 59.4-60.4 Hz - F23-F40
    AC1 Passthrough/Charge (configurable / left at default) 106-132V 55-65Hz - No Faults for violations, only disconnection and re-qualification
    AC2 Passthrough/Charge (configurable / left at default) 80-138V 55-65Hz - No Faults for violations, only disconnection and re-qualification
    AC-Out - 108-130V - F1-F2, voltage only - no faults for frequency

    In general, almost every modern appliance/computer/electronics today will easily run something like 45-65 Hz... And, you should be seeing line frequency from utility in the +/1 1 to 2% maximum range. And an old mechanical governor genset closer to the +/- 10% range (~4 decades ago).

    Had one from Holland in San Francisco with several service calls regarding strange mechanical hiccups ever so often. My turn--I looked and figured out it had the 50 Hz motor pulley. I just put in the 60 Hz pulley instead (~20% smaller), and all was well again.

    With computer power supplies and transformers designed for 60 Hz and running at 50 Hz--You may have poor brown out performance and (for transformers) they may overheat when operated at rated current.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • YehoshuaAgapaoYehoshuaAgapao Solar Expert Posts: 280 ✭✭
    Re: Quick ? -- Ground new pole mount array at pole or at power shed 50 feet away?

    It always reads 60hz the few time I do look at the SCP (I ususally RDP into the netbook in the garage and look through XW-Config). The frequency variations are either less than a second or are not real, such as the inverter measuring a significant distortion as an extra wavelength or the inverter just simply measuring wrong.
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