Is it ok for lightening arrester and surge arrester to share common earthing - that is, to use a common wire and electrode?

Is it OK for the lightening arrester earthing electrode to be close (1 or 2 feet) to household earthing/ grounding electrode?

Context for the question:

A planned household solar power generation installation (location India) shown below (without the lightning arrester):

Solar PV array with net metering

  • 1
    \$\begingroup\$ This entire topic is dangerous. There are significant books on just this. I'm no expert, having only glanced through one of them. But I recall that there are four distinct "rings" of protection against lightening and that the outer-most is there to protect the next inner ring, which is there to protect the next one, etc. The needs of each are different. At the final ring you have the usual protection against fire, shock, etc. that all homes should hope to have. You'll want good, experienced advice here. I know my advice should be treated with extreme suspicion. \$\endgroup\$
    – jonk
    Jan 31 at 3:43
  • \$\begingroup\$ I agree with @jonk above. However, I will add my own thoughts. A lightning strike can be in the 1000s of amps. Even a good earthing electrode will have a resistance to ground measured in ohms. The result could be 1000s of volts between the electrical clamp on the electrode and ground! \$\endgroup\$ Jan 31 at 4:23
  • \$\begingroup\$ @MathK There's an old National Electrical Code rule (NEC) of "25 ohms or less" for the copper ground. Canada has a "1 ohm or less" specified for substations. (These are from memory.) A good quality, brand new copper stake ground in the US will be about 4 Ohms or less. It ages, though. In 10 years that will be perhaps 4 times higher or more. A Ufer ground (rebar in concrete foundation) will likely be less and will stay that way for much longer. But the 25 Ohm rule says that a few thousand amp will mean x-ray radiation levels for the voltage. The arcing itself beaming out harmful x-rays. \$\endgroup\$
    – jonk
    Jan 31 at 4:37
  • \$\begingroup\$ @MathK There is so much to consider in designing a system to successfully withstand a nearby lightning strike. But gas discharge is certainly an important part of it. And taking the arc-overs in steps is also important. (Series strings of gas-discharge modules, for example.) It's a rocket-science of sorts. I'm very interested in learning how to design for it. It's kind of exciting, the idea of actually managing a lightning strike! But I'm ignorant. Hopefully, someone really smart on the topic will chip in. \$\endgroup\$
    – jonk
    Jan 31 at 4:40
  • 1
    \$\begingroup\$ I helped install a lightning arrest system at one point and for grounding they used both ground rods and large area zigzag loops of thick copper wire under the foundation. I'm not sure about belowground, but all aboveground parts of the lightning arrest system were separated and they had a heck of a lot of extra grounding, not just a few rods or plates. Ideally the rod is supposed to bleed off the clouds before they build enough energy for a strike. \$\endgroup\$
    – K H
    Feb 1 at 8:15

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Browse other questions tagged or ask your own question.