Medium Van de Graff – tips and safety


The van de Graff  can have an Earth connected to the bolt at the bottom of the machine, this can be provided from any large metal object, radiators, table tops. Do Not connect this to any part of mains wiring.

Keep away from all other electronics ! – 40,000 volts can kill electronic items, keep your VDG away from anything electrical or electronic.

For best results

Connect an earthed wire to the bolt at the base of the machine, This can be a table top or any large metal object, Do Not connect this to any part of mains wiring.

The foil from the bottom comb needs to be connected to something earthed. You can put a piece of wire around the bolt to a radiator or a large metal item. Do Not connect this to any part of mains wiring

The foil combs need to be close, but not touching. They need to be standing proud of the acrylic and presenting the foil edge to the belt. If this is flat to the acrylic, the VDG will work poorly, or not at all. If the belt is showing back lines on the outside, it  is most likely that the foil is rubbing on the belt.

The foil combs need to be stood up straight with the edge as near to the belt as possible.

The Van de Graaff will run best when clean and dry. It will also run better in cold dry weather.

In dry weather when everything is clean your Van de Graaff kit should be capable of 20-25mm sparks.

If the belt is worn, chaffed or you are unable to clean the belt replace it.

If the atmosphere or your kit becomes damp it will stop working, try drying the kit with a hair dryer and cleaning the kit as detailed below.

If the output is poor and this can be improved by gently rubbing a dry cloth onto the belt, it is likely that your rollers or belt need cleaning or replacing or the humidity is too high. you can check your local humidity levels at if the relative humidity is greater than 50% then you may experience problems with the VDG charging .

If you are in an area with permanent  high humidity, try wrapping the bottom roller tightly with aluminium foil. This decreases the performance, but does work better in humid conditions.


If your Van De Graff fails to run or has poor output, Try cleaning the belt and rollers and/or dry it with a hair dryer.

The motor will run from 6V to 12V, but takes 0.5 to 1A a good battery or power supply is recommended. Avoid using Electronic power supplies.

If the elastic bands get dirty you can wash them in plain soap or washing up liquid. Rince them thoroughly with clean water and don’t use them until they are absolutely dry. The Van De Graff column and rollers can be cleaned with a good screen wipe or lens cleaner, but not one that leaves any form of residue, don’t use baby wipes.

If the motor or belt doesn’t turn, first check the batteries, and make sure the rollers are fee to turn, if the belt is worn replace it.

Do not lubricate any part of the Van de Graaff, The charging works by direct contact between two dissimilar materials. If there is a layer of oil, however small, on the belt or roller this contact doesn’t happen and the VDG won’t operate.

If your rollers or belt no longer charge at all, consider getting a new set with our maintenance kit.