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How to ground - on rock?

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  • Sunking
    replied
    Originally posted by Mike90250 View Post
    Drilling a hole for 8' rod is very straightforward, inspector sees rod, signs off permit.
    Mike one rod will not meet code unless you can prove it test at 25 ohms or less. No electrician will test a ground system as it is a waist of time, so they will drive two rods, collect a check, and call it a day.

    As for a ground system itself, they do almost nothing and are not required in every installation, only if the nominal voltage is greater than 50 volts. In reality th eonly thing a earth ground will do for you is protect your wiring from primary to secondary transformer faults from the utility system. Primary voltages range from 4160 to 13,200 volts on your utility transformers. Each transformer is fused with a 5 amp fuse or less. The earth ground will operate the transformer fuse is the secondary shorts to the primary, or if the primary wiring falls into the secondary distribution during say a wind or ice storm.

    Anyway to answer your question is strictly a code question and all the answers are in Article 250. If you are constructing the house have your electrician use a concrete encased electrode where they bond to the reinforcement steel rebar in the concrete pad, there is no better earth ground. They are also required to use you cold water copper supply pipe. If that is not an option you can use a ground ring.

    Note all electrodes must be used if available. You cannot pick and choose. Your electrician knows this well.

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  • Mike90250
    replied
    Originally posted by Walt_Solartown View Post
    Hello - How can you gound a system if the soil is only a foot deep and below that it's all rock?
    Thanks and regards,
    Walt

    Do you just need to meet code (8' rod ) or do you want to protect your house/gear ?

    Drilling a hole for 8' rod is very straightforward, inspector sees rod, signs off permit.

    If you really want to protct you house & array, you need to install an extensive copper mesh, 2' square, over the whole area. Lot's of expensive copper. has to be under the soil, and the soil kept damp, so it's conductive. But that's about the only way to distribute and disperse a lightning strike on your equipment - give the lightning the easy way to get to ground, not thru your house, but to follow the mesh.

    If you have plans for pouring any concrete, look up/search the interwebs for UFER GROUND

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  • Walt_Solartown
    replied
    This is a home, with utility service available. A grid-tie connection is desired. Array would be on the property in a fenced-off area to keep deer away.

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  • Sunking
    replied
    Is this a home or place that already has commercial AC service?

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  • Walt_Solartown
    started a topic How to ground - on rock?

    How to ground - on rock?

    Hello - How can you gound a system if the soil is only a foot deep and below that it's all rock?
    Thanks and regards,
    Walt
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