150mm Van De Graff kit Safety, Tips, Maintenance and Cleaning


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

The foil from the bottom comb needs to be connected to something earthed. Connect an earthed wire to the bolt at the base of the machine, This can be a table top, radiator or any large metal object, Do Not connect this to any part of mains wiring.

The foil combs need to be stood up straight. The foil combs need to be close, but not touching the belt and 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 and needs adjustment.

The Van de Graaff will run best when clean and dry. It will also run better when warm and in dry weather , either on a hot summers day when the humidity is low, or on a cold winters day again when humidity is low.

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. If this doesn’t improve the output, 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 Weather.com. If the relative humidity is greater than 50% then you may experience problems with the VDG charging .

A humidity meter is available from Extkits here

If you are in an area with permanent  high humidity, try wrapping the bottom roller tightly with aluminium foil. This decreases the performance, but can assist 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.

Do not use any oil, polish, or anything that will leave a residue on the belt or rollers.

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.