Why does hooking multiple extension cords up to another cause a fire hazard?
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Because it is easy to draw more power from them than they can handle. The most common reason you have a bunch of extension cord is you have a lot of devices connected so you use a lot of power.
It is not inherently unsafe if you are within the limits. But most people do not know what they are and the amount of power that is used.
The fuses in your house are designed to protect the cables in the walls. It is not uncommon that a single outlet max current is lower than the current the circuit is fused to. A single fuse is often connected to multiple outlets so this makes sense.
An exertion coord has a maximum current and it depends on its design, it can be lower the what the wall outlet can handle.
This all means you can’t just threaten a bunch of exertion cords as a bunch of wall outlets. The amount of power a bunch of extension cords can handle is lower, An overload will not trigger a fuze like with a wall outlet. An overload can instead result in wires getting to hot, plastic melt and you can get a fire.
In the vast majority of the electrical system, there are no fuzed outlets or in extension cords. The UK system is an exception
The current limit of extension cords is went he cable is out in the open. So if they are in a small space, covered by something or with other electronics that generate heat they can overheat at an even lower current
Extention coord of the roll type usually can’t handle the max current when rolled up, the will overheat.
So the simple induction to not connecting extension cords to the extension cords is a simple way to avoid problems.
As long as your extension cords are rated for at least the same amps as your circuit breaker, this should not be a problem.
If a regular single wall socket can handle 10x draw of power, then your single plug (fridge, tv, phone charger whatever) will either fall under 10x or be more and trigger the circuit breaker fuse. Imagine you plug 10 ext cords into one another and now you can plug 90 plugs into regular single wall socket this way; if you are not careful and counting load at the wall socket, you will MOST likely go above that 10x capacity and create a hazard.
When you connect multiple extension cords together, you are essentially placing two resistors in series. This means that once you plug something in, more of the electricity gets burned by the resistance of the extension cords than if you only had 1. This generates more heat in those extension cords than they were originally designed for, which could melt the insulation and cause a fire.
Because connections create heat. When current is pushed through a wire, it generates heat. The longer the wire, the greater the resistance and the more heat is generated.
A connection like a plug is less efficient than a solid length of wire, because the connection is imperfect. The more connections there are, the more heat is generated, even more than if it were just a length of uninterrupted wire.
Increasing the diameter of the wire, or the surface area of the connection reduces this effect. Therefore, a wire with a fixed diameter has a limit to the length it can be, and the current it can carry. The more connections you make, the lower this limit gets. At some point, the heat generated can reach the ignition temperatures of the various materials.
A. most of the time they are cheaply made or using old cord lying around, connecting too many increases fire risk. Loose connectors/plugs can arc.
B. they are too thin of a cord for the electrical load applied to them
C. the farther / longer a wire is, the less voltage is at the end. To compensate for less voltage, the device being powered draws more amps. More amps makes more heat.
That is why everyone says just buy a bigger cord, don’t daisy chain.
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