Walmart sells ‘regular’ electrical tape $2.27 for 66 feet; auto electrical tape $0.88 for 60 feet: ‘regular’ is more than twice the price of auto. They’re both ‘Duck’ brand, the same width and thickness, rated for the same voltage and temperature.
Somebody figured out that auto mechanics don’t buy electrical tape. Keeping tape from work is cheap so the price had to go down or we would never buy any.
What makes them different? The packaging.
There is, however, a far superior tape for many electrical applications that we used to use on the B-52s 45 years ago, called “self adhesive silicone tape”. It’s now available at WalMart. It’s expensive, but worth every penny IMHO. It’s 100% silicone, stretches, and sticks tenaciously but only to itself. It has no adhesive.
Try it. You may like it.
What makes electrical tape automotive?
1- The word "automotive."
2- The tape marketing department.
CSA
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Duck has 3 grades of electrical tape, looks like the automotive is about the same as their other ‘low’ grade, bet the ‘regular’ one you saw was the ‘mid’ grade.
When it comes to electrical tape I try to stick with one brand, and that is Scotch. Cheaper brands don’t seem to compare in quality. They make all kinds of electrical tape. The silicon tape that “T S M” mentioned is called Scotch 70 and is great stuff. It is also very easy to cut so another tougher tape should be put over it to protect it. Another, more tougher, self fusing tape that is great to use is called Scotch 130. It is a very thick tape that stretches.
Electrical tape turns into a gooey mess when it gets hot. Don’t use it. It will slide off the bare wires and then they will short out. I use the silicon tape sometimes at work. We call it F4 tape, USAF F4. I was in the USAF in the 80’s. When I do wiring in a car I solder the wires and use heat shrink to cover the bare wires. It never fails.
@knfenimore Yes, used in cars, electrical tape has to withstand a wide range of temperatures. I’ve had regular electrical tape get really brittle at -40; the gooey part I have not experienced, but it stands to reason.
I’ve heard that tape called self vulcanizing and self fusing tape.
Those predate the silicon variety.
The gooey is because of the Georgia heat.
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If the backing melts, try Kapton tape. It is a high grade electrical tape that has reasonably high temperature resistance and is a stable dielectric. The acrylic adhesive sticks better than the silicone adhesive. Good news! The acrylic is less expensive. The bad news is that Kapton tape is in general expensive.
Electrical tape is comprised of the plastic backing material and the glue. So between the plastic type and thickness and its mechanical & electrical properties, and the glue chemistry there’s many ways to make it. The best design for home wiring probably isn’t the best for car use, b/c it gets much hotter inside a car, especially the engine compartment. If you use the home-use type inside a car it will usually unwind from the heat and create a gluey mess. That’s a problem you don’t want.
For car use my favorite electrical tape is Scotch Super-33 . It is soft and pliable so can be installed in places where its a tight fit, and holds up well even in the engine compartment.
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Quoth the same mountainbike, 'What makes them different? The packaging.'
That was my thought; the regular is in a plastic blister glued to cardboard printed with useless information; the auto is wrapped in cellophane.
Quoth texases, 'Duck has 3 grades of electrical tape, looks like the automotive is about the same as their other "low" grade, bet the "regular" one you saw was the "mid" grade.'
What differentiates the grades? Both claimed the same specs.
To the many who told me not to use it in my car: I don't, except inside the cab. I mostly use it for non-car purposes.
Quoth GeorgeSanJose, 'The best design for home wiring probably isn't the best for car use, b/c it gets much hotter inside a car, especially the engine compartment. If you use the home-use type inside a car it will usually unwind from the heat and create a gluey mess'
The auto tape is less than half the price of 'regular': why buy regular for any purpose?And quoth the raven nevermore…
For many years the tape used to insulate bare wire was labelled ‘friction tape.’ It was cloth. And harnesses were also spirally wrapped with it. Today split plastic harness wrap is used for wrapping and the vinyl tape used for the bare wire.
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The old fashioned friction tape is still sold and used for hockey sticks and the like. And it still works great. I just bought some for my rake and broom handles. My arthritis makes holding the handles difficult. The friction tape helps greatly, and it’s cheap.
I remember winding friction tape around a baseball bat handle. But then, I remember owning my own baseball bat. Have you noticed what a baseball bat costs these days?
In my case, when I use the tape in my cars, it makes it automotive 
I had never paid attention though, but the auto systems are 12 volt and household are up to 220; could that have anything to do with it?
I didn’t realize there is a difference in electrical tapes. Back in the mid 1950s, when I was in high school, i rewired the old farm house we lived in because it all ran,on one fuse and the box was located on the front porch. My dad was leary of wire nuts, so every splice that I made, I twisted the wires together, fluxed the joint, soldered the joint, wrapped the joint in rubber tape and then the plastic electrical tape. I know it gets hot in a car, but it couldn’t be any hotter than that attic. To complicate matters, the house had all oak beams that had hardened over time. I had to drill into the beams to set a junction box. The house is still standing 60 years after I did the work. However, any electrical connections I make today are made with wire nuts.
The auto tape is less than half the price of 'regular': why buy regular for any purpose?
I get generic electrical tape for around 50 cents a roll, usually in multi-roll packs; but the Scotch-Super 33+ is quite a bit more expensive than that. Around $3.50 per roll as I recall.
I passed by the electrical section of Walmart the other day; I saw electrical tape $0.57 for 60 feet; it was a different brand, some no-name.