I would probably have a legal disclaimer out of an abundance of caution. That being said, you have a right to free speech via First Amendment guarantees. While that right is not absolute and some words “by their very utterance” cause injury or incite an immediate breach of peace, and do not receive constitutional protection, (there is the old adage you do not have the right to shout fire in a crowded movie theater). This (your blog) is not that. To take it to its logical (or illogical) extreme, there are many things on the internet, in magazines, scholarly articles, etc. that could injure someone or cause damage in the event that one who was not qualified or competent to perform the action described undertook to do so.
A child could burn themselves following the directions on a mac and cheese box but they shouldn't be cooking in the first place. The same rings true for high voltage electricity - a non-licensed electrician should probably not create a high voltage power supply. But, will some? Yes. But you are not liable for printing a blog about the practice.
On another but related note, if you are a licensed electrician your licensing authority may require that you take precautions to ensure you do not inadvertantly direct others to engage in practices of licensed professionals that could cause harm by giving them information. I doubt this but I don't know because I am not an electrician.
As far as could you be liable for writing it....under our legal system you can be sued under a theory of negligence for just about any action someone thinks was unsafe or causes injury. And you never know what a jury will do. But I think that to sue someone for simply writing something would be fairly easily dismissed through a motion for summary judgment by a competent attorney in the event you got sued. If everything a person wrote, that if followed by an unqualified person resulted in injury, resulted in liability for damages than it would have a chilling effect on their First Amendment right to free speech.
That said, I go back to my original statement that it couldn't hurt to have a simple liability waiver for extra protection. It could be something as simple as:
"The information contained herein is not mean to be comprehensive and is for informational purposes only. You should not undertake to perform anything described herein without adequate training and/or supervision. The Author disclaims any responsibility for any injury, damage, or loss as a result of reliance upon the information found on this site/blog."
If you do use a liability waiver, make sure it is bold and obvious. Otherwise, it can backfire!