Grounding - polarity

[Richard Hull]

It is important in all electrical work to make sure that proper grounding is made to electrical devices for safety and fire prevention purposes.

The key thing is that the fusor body itself, if metal, MUST be at ground potential. The fusor's shell is positive with respect to the inner grid. The grid is considered a negative or minus HOT. Therefore, the power supply is effectively considered a positive ground supply.

Inorder to read fusor current safely, we will have to install a resistor between the supply positive lead and ground. This resistor MUST be a high wattage wire wound low value resistor for safe operation of the system. (see "measuring fusor current" post)

Remember the fusor must be actually connected to ground and not to ground through the current metering resistor! The supply, instead, must have its positive lead taken to ground through the resistor.

The negative HOT supply lead of the supply is a lethal thing and should be shipped over to the fusor's hv insulator (inner grid) via a cable whose insulation is competent to handle, without arc through, the full maximum potential of the supply. You wouild be wise to locate the supply close to the fusor and run even the insulated cable through a second safety insulator like PVC pipe.

Failure to ground properly could leave you dead if you touched the fusor while running or at least damage instrumentation through HV pulses radiating back through a lifted of broken ground.

Bolt a ground cable to the body of the fusor.

Richard Hull

[guest]

Anybody who disregards Richard's advice on grounding will be strumming on a harp. I've seen too many research accidents where electrical conventions
were ignored for the sake of cost or speed... TRADGEDY.

Larry Leins
Physics Teacher