Crazy ground question--anodic protection

Discussion in 'General Technical Questions and Answers' started by KC1LBB, May 29, 2020.

ad: L-HROutlet
ad: l-rl
ad: Left-2
ad: HRDLLC-2
ad: abrind-2
ad: MessiPaoloni-1
ad: L-Geochron
ad: L-MFJ
ad: Left-3
  1. KC1LBB

    KC1LBB Ham Member QRZ Page

    So, I live in a 1920s house, where the primary house electric ground is the cold water main (I presume it's iron in the ground), connected to the breaker panel by an approximately 15 ft section of solid conduit (I think steel, could be copper).

    I'm planning on sinking additional ground rods for lightning and RF grounding, and tying it all together with 6AWG copper. Is the bonding of dissimilar metals going to be a long term issue for the galvanic corrosion of the iron? Should I just bury a $15 water heater zinc for peace of mind? Has anyone actually seen corrosion like this?

    I'm thinking this is a pretty paranoid problem, but if the water main is replaced on 100-150 year time scales maybe not. (Most of my life is in/around boats, where this is a real issue--I even took a class on it in college, but not so much on how in soil impacts the orders of magnitude. Also, I can do the math, but figured I'd ask first.)

  2. W1VT

    W1VT Ham Member QRZ Page

    You want to talk to someone locally about this. There could be an issue like the crumbling foundations in Connecticut that doesn't concern people elsewhere.

    While older homes are often grandfathered, or exempt from new building requirements, perhaps you should
    consider bringing your home up to current standards if stuff like this bothers you. The peace of mind it brings may make it a worthwhile investment.

    New construction isn't necessarily inferior to old if you are willing to pay to have it done right.
    Old construction often seems better because we only see the quality examples that still survive.
    There was plenty of junk built in the old days that isn't around anymore.
    Last edited: May 29, 2020
  3. KC1LBB

    KC1LBB Ham Member QRZ Page

    The thing driving the grounding upgrade is I'd like to move some antennas outside, so I'd like at least a lightning ground for them--and then tying that ground to the existing ground to prevent ground currents.

    I'm sure the best thing is to just install a proper entry point ground (not the easiest, since the panel and meter are in the exact middle of the basement). Part of me doesn't want to mess with what's there because the house ground is really quite good.

    I'll probably compromise with a zinc buried near the water main and tied into it, $15 for some piece of mind. I could always hook it up and put some current meters on the ground interconnects and log the data too--might be a neat little experiment on buried metal electro-potentials (hypothesis: weather/rain driven cyclic variation of current).
  4. WR2E

    WR2E Ham Member QRZ Page

    How do you know?

    Regarding cathodic protection: I'm nearly 100% certain that electrolysis is what cause my underground fuel oil tank to turn into swiss cheese. It was installed adjacent to the ground rod for the house. My neighbor's tank installed at the same time back in the late 50s but on the opposite side of his house from the AC service drop was FINE when it was removed.

    You may be on to something!
  5. AA4PB

    AA4PB Ham Member QRZ Page

  6. KC1LBB

    KC1LBB Ham Member QRZ Page

    I like the bronze for the local corrosion issue! I was thinking when moisture is high enough to complete the battery circuit back you could just get a low low low current that over years could be an issue.
  7. KC1LBB

    KC1LBB Ham Member QRZ Page

    I'm just saying (purely qualitatively) the house electrical is well suited to large inductive load starts and I've seen no ground related issues--probably not a great ground indicator, you're right I can go do some actual data collection instead of wild speculation.
  8. WR2E

    WR2E Ham Member QRZ Page

    I don't think it's necessary... I was curious though and thought perhaps you already did.
  9. WA4SIX

    WA4SIX Ham Member QRZ Page

    If you look closely at the conduit connection to the pipe, you might notice a wire in there. It's an old style of grounding. Leave it be, or snug it a bit if not corroded. Add a new ground system for your antennas with rod & connect where the old ground is.

  10. N0TZU

    N0TZU Platinum Subscriber Platinum Subscriber QRZ Page

    If it was me with a house that old, I’d get a licensed electrician for come out for an hour to make sure the grounding system in the house is still operational and adequate for modern use before adding anything to it. He should be able to advise about dissimilar metals issues for when you bond your antenna ground system to it.
    K0UO and WR2E like this.

Share This Page