High Voltage Wiring

WARNING - This page is NOT intended to tell you how to make high voltage wires safe. It is intended only to show you how I do high voltage wiring to prevent losses along the wire path from the power supply to the final destination. These techniques have not been used by me above 75kV. Working with high voltages is extremely dangerous. Use this information at your own risk.

Use insulated wire

Bare wire (e.g. bare copper wire), if it is at high voltage with respect to ground, will leak electrons. Electrons from the wire will attach themselves to molecules in the surrounding air, ionizing the air. This means you will have a lower voltage at your destination than you could otherwise have. This is the reason for using insulated wire instead. You'll have less leakage.

How much insulation you need depends on how high the voltage. For voltages such as I work with, 10kV and higher, you should use special high voltage wire. That's not to say you shouldn't use it for lower voltages too. In fact you probably should. I just don't know what the lower range is where you should start worrying about it. This wire has plastic around it along with a layer of other wire insulation. If you've ever looked at the wire leading into the back of a CRT (cathode ray tube) in a TV or computer monitor then you've seen a high voltage wire. I don't use high voltage wire because I don't have a ready supply of it.

I use what I call multimeter wire, though it seems to be thicker than the wire used with my multimeters. The conductive wire itself seems to be about 18 AWG and is stranded. With the insulation the outer diameter is about 1/8" or 3.5mm. I buy it from a good local electronics store and they cut it to whatever length I want.

My multimeter wire.

I've seen some experimenters use much less insulation but they usually work around 30kV whereas I'm typically as high as 50kV.

Note once again - This insulation is to reduce leakage. It does not mean you can go near the wire yourself. Doing so will result in a shock, possibly leathal.

Custom insulated connectors

Where two wires join is another place where leakage/losses can happen. The ends of wire, especially standed wire, have sharp points. Twisting them together doesn't do the job since the sharp points will still be there. Some high voltage researchers go as far as to submerge the connection in a container of insulating oil (e.g. mineral oil available at drug stores). Wax (available in some grocery stores and for making candles in craft stores) is also a good insulator. I've heated wax on a stove to make it liquid and then poured this into a container that had my connection in it. When the wax hardens (usually give it 24 hours if it's paraffin wax) you have a well insulated connection. These techniques are especially necessary for higher voltages, maybe above 75kV.

Most of the time though, I make a custom plug and use a butt connector as the following pictures show. It works very well for preventing leakage up to 75kV (the highest I've measured doing as of this writing).

I first trim and twist the end of my wire about 6mm or 1/4". I also cut a piece of copper tubing (available at hobby stores) to the same length. Use tubing that slides easily over your wire. Mine has an inner diameter of about 1.5mm or 3/32".

I then put solder on the wire and put the tube on part way. I then add more solder to the part of the wire still exposed and then use the tip of my soldering gun to push the tube on the rest of the way. This firmly attaches the two.

I next cut about 55mm of black electrical tape...

... and wrap it onto the insulated part of the wire beside the uninsulated end. The reason for the tape is that it will be pushed into the butt connector. If the tape weren't there then there would be an uninsulated air gap inside the connector.

Here is the end result - two wires connected together in a well insulated manner.

The package the butt connector comes in. The part number is 20-6934-4 but you'll likely improvise all of this and find whatever you can get locally. These I get in the automotive section at Canadian Tire.

An example of these connections in use.

Staying away from ground

Saying that a wire has a high voltage on it means that its voltage is numerically far from the voltage of the planet Earth. Your house, floors, table, ceiling, and YOU all are connected to Earth and have a voltage on them that is numerically close to that of the Earth. If your voltage is far from Earth, it can still be far from the voltage on your wire (it's not unusual for a person to be at 10,000 volts but if your wire is at 30,000 volts then you're still 20,000 volts from your wire!) So if you have a wire that has 30kV with respect to ground that means there is a difference of 30,000 volts between your surroundings and that wire. That difference means that electrons from that wire have a very strong desire (30,000 volts of desire) to jump from that wire to your surroundings and you.

So if you have an insulated wire sitting on a table (whose voltage is near ground) then there will be more electrons leaking through that insulation than if that wire were hanging in the air. To suspend my wires in the air I use plastic pill bottles. Glass jars are also good. These are all insulators so the electrons have less of an ability to go into them.

Here are some examples that I've done in the past.

You can see the pill bottles taped to the side of the table on the right. They have multimeter wire on them. The wires going from the glass jars to the lifter (the triangular flying thing) are bare wires because insulated wire would be too heavy.

This shows the use of plastic at various places (in this case various white plastic pieces). Wood is a semiconductor and therefore not a great insulator. The balsa wood in this picture is part of a frame that has plastic joints and is sitting on a plastic insulating plate (not shown).

This one isn't an example of insulated wire but it shows the use of pill bottles very well. In this case I'm making a high voltage probe and testing the resistors. I've zigzagged them to save space.