2
$\begingroup$

I used some copper pipe outside to string some decorative lights up higher in my yard. I used the copper because I thought it would be pretty and patina nice.

Then I remembered that copper is a good conductor, and there's a lightning storm outside. Should I be concerned about attracting lightning strikes? It's not grounded.

$\endgroup$
  • $\begingroup$ Welcome to Earth Science SE! For any further assumptions on your question, there will be much more information needed - especially about the environment of your house. $\endgroup$ – Arne Apr 13 '16 at 22:07
  • $\begingroup$ Central Texas, the patio that has the poles is under a tree. 15 x 15 foot area $\endgroup$ – Betsy Dupuis Apr 13 '16 at 22:08
  • $\begingroup$ If the tree is taller, then any lightning strike should hit it first. That being said a lightning strike is like a 600 lb gorilla - it goes where it want to. Since the lights are probably connected to your electrical system the lighting could travel through the house wiring and blow up nearly anything and/or everything. $\endgroup$ – MaxW Apr 14 '16 at 4:06
  • $\begingroup$ Probably best to take it down just in case. $\endgroup$ – Betsy Dupuis Apr 14 '16 at 19:53
3
$\begingroup$

Any build up of static electricity in the ground will seek to connect with opposite charge in a storm cloud, and will spark through the line of least resistance. Any high metal structure, whether it is copper or not, is a candidate for the line of least electrical resistance. You may be able to protect your copper support by a higher lightning conductor (sharp spikey, high, pointing up, and well earthed, preferably to the local water table). Also bear in mind that the lightning can jump over short distances possibly to your copper support.

I once observed a lightning strike on a house close to where I live in South Australia. The lightning hit a TV aerial, jumped to the metal guttering around the roof, jumped to metal window frames, and made contact with the house's internal wiring. It was like a bomb had gone off. Every electrical appliance that was plugged in was fried. The guttering kind of exploded, and a sour smell of 'charred house' lingered for weeks.

So yes, you should be concerned!

$\endgroup$
3
$\begingroup$

The easiest thing to do to make your copper pole safe would be to ground it and disconnect the lights from your house wiring when they aren't in use (if they are plug-in lights and not solar). This article on how lightning rods work is a pretty good explanation of why you do want to ground a tall, conductive pole.

Electricity will travel the path of least resistance to ground. That's why folks working on electric lines have insulating shoes and gloves, but folks working on equipment sensitive to static electricity wear grounding straps. When you're working with high current or potential, you don't want to be the shortest path to ground. When you don't want the sensitive equipment you're working on to be the shortest path to ground, you attach a strap to yourself to provide a better path to ground for any static charge that might accidentally build up.

When lightning strikes, the energy will take the path of least resistance, and has so much power that it can jump small air gaps. If the gap is small enough, and close enough to a good conductor, it becomes the shortest path to ground.

A copper pole is definitely a good candidate for lightning to use as a path to ground, so what you want to make sure of is that the lighting travels completely down the rod to ground, and doesn't jump to, say, the wires of your lights (through their insulation) and travel into your house wiring, frying electronics and generally wreaking havoc. The best way to do that is to ground it properly and make it a sort of lightning rod. It won't "attract" lightning strikes, but if one does occur, it is safer to let it follow the pipe to ground than maybe hit your house.

As an aside, according to a lightning primer from NASA although cloud-to-ground lightning is the most dangerous and damaging, it is the least common.

$\endgroup$

Your Answer

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

Not the answer you're looking for? Browse other questions tagged or ask your own question.