Is a capo safe to use on an electric guitar?
Let's find out if this is true or not.
Many moons ago I was told by somebody (I honestly don't remember whom) that you should never put a capo on an electric guitar. Why? I wasn't told that part. But gosh darn it, you'd better not do it or bad things will happen.
Is this true? No. Or to be more specific, using a capo on an electric guitar neck is only bad (somewhat) in a very specific situation which I will explain in a moment.
Use the right capo
Most capos can support both nylon and steel strings. But if the capo is specifically made for nylon strings, chances are the capo spring won't be strong enough to hold steel strings down to the fret. The reason for this is that since nylon strings hardly require any pressure to hold them down, only a lighter capo spring is required. With steel, more pressure is needed, hence the need for a stronger capo spring.
When shopping around for a capo, the product listing should state up front what type of strings it will support.
If you want something that will absolutely work on an electric, use what I use, the G7th Performance Capo. It will hold strings down on an electric without buzzing all over the place. I've had mine for years, and it still works just as good as the day I bought it.
Will a capo damage an electric guitar neck?
Contrary to popular belief, it will not damage frets, not screw up the truss rod and not damage wood if you use one properly.
How to use one properly? Follow the same rules for capo use as you would on a steel string acoustic. Place the capo properly on the neck, don't squeeze it super-tight, avoid bending notes when the capo is in use, and always remove the capo when done playing.
The one instance where you shouldn't use a capo on an electric guitar is...
...when the neck is finished with nitro. More specifically, brand new nitrocellulose lacquer.
Guys that spend the extra cash on a nitro finished neck do want wear to happen, but only from the fret hand and not a capo. Use of a capo may result in premature undesirable marring of the nitro finish.
Yes, I am saying the entire reason to avoid capo use on an electric guitar with newly finished nitro is specifically to promote a more desirable look over time from fret hand wear only. Fret hand wear is the desirable wear, while wear from a capo is undesirable.
Acoustic guitar players that regularly use capos on new guitars with nitro necks will tell you capo use is 100% okay. True? Yes. But bear in mind they're all using necks with significantly darker woods. On electrics with light color necks (e.g. Fenders with maple necks), premature wear is a lot more obvious - especially on necks finished with nitro designed to wear quickly (e.g. Fenders with "thin skin" nitro).
In the end, it's all about appearance first. Use of a capo on a newly finished light color nitro neck may result in an undesirable look on the back of the neck over time.
If you really really care about the look (and let's face it, if you're dropping several thousand on a Fender "thin skin" nitro finish guitar, you do care), don't put a capo on it.
What neck finish handles the capo best on an electric?
Just about anything not nitro.
However, best-of-the-best would be gloss urethane just because it cleans up so easily and can take a ton of abuse.
Fortunately, most electric guitars do have gloss urethane finished necks, so chances are you already have the best neck finish for capo use.
My experience with capo use on an electric
I've never had a problem with it. My capo use has never resulted in wood damage, fret damage, finish damage or damage of any kind.
However, I do use a quality capo.
Ordinarily, it's true the word "quality" doesn't mean much where guitar stuff is concerned, but in this instance it actually does. Don't go cheap with your capo, because it won't hold the strings down properly, lose its position periodically and quickly become annoying to use.
It is worth it to spend extra on a better capo. Again, I've been using the same one for years. Originally, I thought I spent way too much when I originally purchased the one I did (it's the one pictured at top), but it's lasted the test of time and still works great, so I have no complaints.