If you’ve ever seen a tree split in half after it’s been struck by lightning, you might have wondered “can electricity travel through wood?” Or stated more technically – does wood conduct electricity?
The short answer is that wood is generally not a very good conductor of electricity, but there are certain factors that can greatly increase its ability to conduct. The main one being how much moisture is inside the wood.
As you may be aware, water is a strong conductor, which is why mixing water with electricity can be a serious hazard. When wood becomes wet it too can act as a strong conductor.
Untreated wood readily absorbs moisture, which means a sudden downpour can turn dry poorly conductive wood into a strong conductor.
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What Else Affects Woods Ability to Conduct Electricity?
Before we can dive into some of the things that can influence if electricity can travel through wood it’s important to define what we mean when we say ‘wood’.
When most of us think of wood we probably picture a 2×4 from the hardware store or maybe a tree branch, but we don’t consider that wood is actually made up of a number of biological structures like cellulose, hemi-cellulose, and lignin. That means wood varies significantly from one species to another, and even between two trees of the same species.
Also consider that the lumber we use for building things comes from trees, which are designed to move water up from their roots into their branches and leaves. That means trees are naturally very good at absorbing and retaining moisture and a living or recently cut tree will contain a lot of water.
With so much variation in what we call ‘wood’ – a precise answer to ‘can electricity travel through wood’ isn’t really possible. But we can say that dried wood is a poor conductor and that wet wood can conduct electricity to varying degrees.
Voltage
Another thing to consider is the voltage you’re dealing with. Conductivity is relative depending on the amount of voltage you’re dealing with.
High voltage current is able to breach through a weak insulator like wood. That same wood would prevent a low voltage current from passing through it.
That’s because electricity follows what we call electrical potential, which is a measurement for how many electrons you can push through a material with a specific amount of pressure (which we refer to as voltage). Electricity is always trying to travel from a positive terminal to a negative terminal. We often call the negative terminal “ground”.
When it comes to wood, which is a weak insulator and a poor conductor if the electrical pressure (voltage) is strong enough it can overcome the fact that wood isn’t a great conductor.
In practical terms, this means high voltage electricity can travel through wires into things like wood ladders and long-handled wood pruning tools. You can even get shocked by leaning a wooden ladder against a tree that’s in contact with a power line.
Can Electricity Travel through Trees?
You’ve probably heard warnings about avoiding tree branches or fallen trees that are in contact with power lines. These should be taken seriously, as electricity is able to move through power lines and into branches with relative ease.
High voltage wires can even spark or arc from a wire to a nearby branch that’s not physically in contact with the wire. This doesn’t occur under normal circumstances but can happen if there is a power surge or a lightning strike.
An extreme example of this is when lightning strikes a tree during a thunderstorm. When this happens, water inside the tree starts to boil causing steam to form. This can cause cracking, stripping of bark, and even explosions.
All this to say trimming, pruning, or cutting trees near power lines should be avoided at all costs. Power lines carry voltage up to a hundred times greater than the current on an indoor outlet – and even those can give you a pretty serious shock.
Is Wood a Good Insulator?
We’ve already established woods’ ability to conduct electricity – especially when wet – but how does it measure up as an electrical insulator?
An electrical insulator is a material in which electric current is not able to flow freely. Essentially an electrical insulator is the opposite of a conductor.
Wood is a reasonable insulator, especially when it’s dry. When water is added to the mixture it becomes a stronger conductor and weaker insulator.
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