yet another Grounding Question ....

rgearhead
rgearhead Solar Expert Posts: 38 ✭
in General Solar Power Topics #1
Hi all, kinda weird Grounding question if you will :blush:, as for my DC=charge controller, Inverter, battery bank -, Are all grounded at the same point 3' away to my 4" cast iron sewer line right before it leaves threw my foundation, and my PV panel that is 70' away has it's own 6awg from the frame to a lightning rod 15' away where its very shallow(4'drop off my back yard )and I drove the rod 6' down...

If all above sounds ok, Great... but as far as powering things down stream on the AC side with my Inverter, I was wondering, 4 years back I had the Entire house re-plumed and the sewer line that my DC is all grounded to is fed from drains that were once metal and are now all PVC ....I do see my house breaker panel gets its main ground from the water supply line right where it enters my house by the water meter... should i tie the sewer line im using for DC ground to the local water supply lines or house conduit ? so it's all on the same page? or is it ok the way I now have it....


Thanks Bob....
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Comments

  • Aguarancher
    Aguarancher Solar Expert Posts: 315 ✭✭✭
    #2
    Re: yet another Grounding Question ....

    You don't want your ground anywhere near a lightning rod or the rod anywhere near your PV panels.
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  • rgearhead
    rgearhead Solar Expert Posts: 38 ✭
    #3
    Re: yet another Grounding Question ....
    Aguarancher wrote: »
    You don't want your ground anywhere near a lightning rod or the rod anywhere near your PV panels.


    sorry I miss spoke (typed ) my PV Frames are tied to a grounding rod(not lightning rod) buried in the earth all 85' from my house n sewer ground ....
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #4
    Re: yet another Grounding Question ....
    Aguarancher wrote: »
    You don't want your ground anywhere near a lightning rod or the rod anywhere near your PV panels.

    Yes; this needs to be clarified as to whether the PV frame & mount is connecting to an actual lightning system (wrong - do not do this) or to a separate rod at the PV as opposed to being tied to the other grounds.

    Second clarification needed: the sewer line that is outside the house and underground is cast iron or PVC? If it has been switched to PVC outside then there would no longer be sufficient contact for the cast iron inside to be a good ground. In that case at least tie it to the water pipe ground.

    Note also that these two types of 'pipe grounding' are no longer used because they are deemed insufficient (change in resistance over time). Separate, dedicated grounding rods/plates are allowed as are Ufer systems.
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  • rgearhead
    rgearhead Solar Expert Posts: 38 ✭
    #5
    Re: yet another Grounding Question ....

    Ugh'' the PV frames are on there own (stand alone ) grounding rod far from the house but close to the PV.... the cast iron sewer line is still cast iron out side the house to the street, It's where most drain lines Inside the house Have been re-piped in PVC...Here is what has me scratching my head Cariboo, I power several tools with high AMP draw once in a while with no problem I'm talking, heat gun pulling 9+amps, and a dehumidifier that pulls 10+ AMPS for over an hour at a stretch... just to really load test my inverter n system...

    So my main goal would be to be able to run my furnace for a cycle(5-10minutes ) in heating in a grid down EMERGENCY winter situation, the furnace is Natural gas and bran new, I just installed it last winter..

    according to furnace manual max amp draw is 11.5 , first attempt at powering the furnace off my pure sine 1,800 watt 12 volt inverter was FAIL... I shut off the furnace breaker and was trying to feed it from a service receptacle right on the furnace, I know** not legal, proper, sinner, ect,ect... this was a test to see if my inverter could do it, then I would go proper switch gear n all, well the second I plugged in and turned on the Inverter (furnace local controls still off )the GFCI kick out....so then thinking turning off the breaker just shuts off the Hot leg there was a conflict on the neutral leg, So I installed a 2 pole disconnect on the AC feed to the furnace that shuts down the neutral n hot feed..

    well on second try, shut off disconnect, powered up inverter all hooked up and GFCI stayed on, and I was at furnace looking at my kill o watt metter to follow the AMP's on start up, all looked good , then I turned the switch on the furnace to on and was watching meter as furnace did it's check list and the blower was starting ( it does a soft start ) the amps climbed to about 1.5 amps and the GFIC on the inverter tripped.. So was wondering if it is because my Dc side ground is Isolated from house ground ?? either that or amp's spiked so fast i couldn't see it on the meter and inverter cant handle it ??
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #6
    Re: yet another Grounding Question ....

    It sounds like your furnace has electric ignition of the type that requires Earth ground for the igniter to work properly. It is not going to work through a GFCI connection. At least not reliably. It isn't the furnace that's failing here but the inverter's GFCI because of the grounding need of the igniter.

    Personally I prefer no GFCI except at point-of-use or on a dedicated "wet circuit" as they do tend to false trip and cause other problems, or burn up themselves.

    Caveat: if this post is somewhat incomprehensible it is due to necessary pain meds I'm taking on account of having a tree fall on me last week. I'm better first thing in the morning. :p
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  • westbranch
    westbranch Solar Expert Posts: 5,183 ✭✭✭✭
    #7
    Re: yet another Grounding Question ....

    Marc, this is just NOT your year!...
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
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  • rgearhead
    rgearhead Solar Expert Posts: 38 ✭
    #8
    Re: yet another Grounding Question ....

    all good, make's scene ... Hope you feel better soon, thanks Bob....

    last question for the day err tomorrow am : ) , would my DC system be better off being sure it is 100% tied into the house ground = water supply pluming and house wiring conduit...
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  • Organic Farmer
    Organic Farmer Solar Expert Posts: 128 ✭✭
    #9
    Re: yet another Grounding Question ....
    rgearhead wrote: »
    ... Are all grounded at the same point 3' away to my 4" cast iron sewer line right before it leaves threw my foundation, ... but ... drains that were once metal and are now all PVC ....I do see my house breaker panel gets its main ground from the water supply line right where it enters my house by the water meter...

    Your house main-breaker is grounded via the water supply line. I would not trust the sewer line. I would add a new ground rod outside and run 6awg to the CC / Inverter.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #10
    Re: yet another Grounding Question ....
    rgearhead wrote: »
    all good, make's scene ... Hope you feel better soon, thanks Bob....

    last question for the day err tomorrow am : ) , would my DC system be better off being sure it is 100% tied into the house ground = water supply pluming and house wiring conduit...

    NEC requires the grounds to be the same or connected.
    But it also now requires DC GFCI which plays havoc with DC grounding.
    If this is not going to be code inspected, ground the negative to the house grounding point. Tying that sewer ground to it would be a good idea too. Or perhaps putting in a new and proper ground rod.
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  • verdigo
    verdigo Solar Expert Posts: 428 ✭✭
    #11
    Re: yet another Grounding Question ....
    Cariboocoot wrote: »
    or to a separate rod at the PV as opposed to being tied to the other grounds.

    Need a clarification to the clarification. I have my PV frames grounded to a separate grounding rod that is NOT connected to the system ground rod. Right or wrong?
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #12
    Re: yet another Grounding Question ....

    "Right" in terms of lightning protection.

    "Wrong" in terms of -- If there is a short from Solar (or any 120/240 VAC cord/tool) to the frame, the fuses/breakers back at the main panel will not trip.

    Lots of discussion about how best to ground--But my 2 cents would be to put a 6 awg minimum copper wire from the remote ground rod back to the main panel ground rod/water pipe so the array cannot become "energized" and shock somebody (i.e., a short between >24 VDC or VAC and panel frames/mounts--Somebody walks up in wet grass and touches exposed metal--Shock and/or electrocution possible.

    If you use GFI (Ground Fault Interrupting) outlets/breakers on any AC tools near the array--Then you cannot get an AC fault with respect to ground (GFI will trip). However, a DC fault from the array + lead to metal frame is possible... Pretty much any code calls over 60 volts as hazardous.

    -Bill "short answers are not my style" B. :roll:
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • rgearhead
    rgearhead Solar Expert Posts: 38 ✭
    #13
    Re: yet another Grounding Question ....

    thanks for all the input, sounds like i sure need to give the house ac a better ground than just the pluming, thanks...
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