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Does an undersized grounding is cause for concern about improper / unsafe condition(s) that I noted at the house’ s electrical sub panel. The House that was built in late 1950’s, Southern California, However, The original main panel was replaced with 125A, which supply central HVAC / 50A and sub panel / 60A. All branch wiring, including 30A sub, is fed into the aforementioned 60A sub panel. Grounding to the main panel is done via rod and connection to a water-supply metal piping. The concerns are; Undersized ground conduit from the main to the sub panel, not #6. The lack of proper ground from the 60A sub panel to the 30A sub, laundry. House’ s receptacles are a combination of 2 and 3 prongs. Do I need to upgrade the ground’ s conduit from the main panel to the sub panel / 60A? Is the 30A sub panel wiring of concern?
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  • Can you get us a photo of the labeling on the inside front of the laundry subpanel please? May 4 '20 at 2:14
  • Also, do you know how long those flex conduit runs going out the bottom of the primary subpanel are? May 4 '20 at 2:18
  • Thank you for the feed backs. Attached is 30A label pictures. I have attached additional main panel's pics of the Ground Rod. The flex conduit runs is approx. 30-35 ft. What are really the consequence, if any, of having an interior-type 60A , as being housed inside a metal enclosure.
    – H1991
    May 4 '20 at 16:47
  • Can you get us close-ups of where the wires leave into those flex conduits please? May 4 '20 at 23:59
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The main panel appears to have a nice fat braided ground on the ground rod.

For the 60A subpanel and 50A A/C service, a 10 AWG ground wire is perfectly adequate. Not seeing the problem.

The 30A sub is a Zinsco, which some very serious fire-starting problems with its buses, which can't be fixed by swapping breakers. Since it appears to be configured as a disconnect switch anyway, maybe you can replace it with that.

I could do without the artiste "runt"-ing off all the wires to barely long enough to go where they're going right now. You'll hate that guy if you ever have to put in GFCI or AFCI.

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  • Yeah, it looks like the meter-main and primary subpanel are good to go, save for the fact the primary sub is an indoor panel that's been weirdly adapted for outdoor use (with the overcover). The only issue I see grounding-wise is with the laundry subpanel (not only is it a Zinsco, I suspect the ground path is via flex conduit, which is nogoodnik if it's any significant distance, and the bond screw there is still installed as well) May 4 '20 at 4:18
  • When the Zinsco panel was installed it was code compliant to have the sub neutral and ground bonded , that changed in 99 that was a rough year getting used to that change. I don’t remember Zinsco making it into the 80’s
    – Ed Beal
    May 4 '20 at 14:58
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A 60 amp sub can be grounded by #10 copper per 250.122 the main panel should be #6 to the rods / pipe electrodes , you say the ground is undersized without specifying what is there and or exactly how the system is grounded and the year it was done , in 99 there are were major changes to grounding and bonding. Back when the home was built only the main panel was grounded to the water pipe no supplemental ground Was required.

Without knowing the size of the grounding electrode conductor or how it is grounded we cannot say if there is a concern or not.

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If the conduit is metal and continuous (and properly assembled)

any green ground wire is an extra.

No green wire at all would be an adequate ground, as metallic conduit is a grounding conductor (with a possible exception related to pool equipment?)

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    That's only true if you're dealing with rigid metal raceways (RMC, IMT, EMT, surface metal raceway, and metal strut-type channel raceway, primarily). The NEC, in 250.118 points 5, 6, and 7, limits the total length of flexible metal conduits (FMC, LFMC, FMT) in an equipment grounding path to 6' -- if you put more than 6' aggregate of FMC/LFMC/FMT in a run, you must run a ground wire inside it. May 4 '20 at 2:37

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