Earth Rod

I assume you're referring to equipment earths and lightening discharge earths which should be separated.

Good grief, I can't believe I got the discharge rod wrong. The number of times I've used them……..

I'm just going to take a guess, because that is not the terminology I am used to using.

I'm guessing that the Earth rod is the ground rod (or grounding eletrode network) for the grounding of electrical equipment, and that the discharge rod is the ground rod (or network) for lightning arresting equipment (e.g., lightning arrestors).

In the (US) mining industry, separate grounds for each are required, and, iirc, must be separated by a minimum of 25 feet.

Earth Rod is one of the earth electrodes used in earthing or grounding. The method is called Rod Earthing. It could be a Copper or Steel rod of adequate size. It is normally buried under ground.

Wheras, a discharge rod is a hand-held portble device. It is normally an inulated conductor with a bare metallic edge at one end (top end) and a metallic screw or bolt at the bottom end, which will be connected thro a wire to an earth grid during a discharge operation. The outer circumference of the discharge rod is fully insulated. While wotrking on electrical equipment, particularly, high voltage, after shutting down the equipment for maintenance, it is advisable to discharge any trapped charges or stored energy to the ground, so that it is fully safe for the maintenance person to touch and work on the equipment.

Sir,this is the statement I found in our training manual.

"After shutting down,the equipment/line should be earthed only after discharging."

Here what they mean, the difference between earthing and discharging.

Regards

gova

I too am perplexed by the statement. Can you read the complete paragraph for me so that I can try to comprehend?

"After shutting down, the equipment/line should be earthed only after discharging."

I know I've had one blonde moment in this thread, but surely the statement should be the other way around. I for one wouldn't be happy using a discharge probe on an unearthed system.

I think that's an improper use of English in the translation. To me, that would mean "Don't connect the line to earth (ground) unless power has been removed from the line" or words to that effect. "dicharging" in this case would mean removing the "charge" from the line, i.e., power.

Unless there is a discharge terminal in the circuit, as in a capacitor bank which is not referenced to earth ground and discharging there would not provide complete exhaustion of the bank's charge.

So many variables.

Earth rod is a rod which is burried under ground and 10% of it's length remain above the ground. It may be used as neutral or eqipment earthing and connected to equipment to keep the working personnel free from electric shock.

Discharge rod is a hand held mobile/ portable rod whose body is insulated and the top portion has a metal clamp. A copper shunt can be connectd with this clamp and the other part of the shunt is remain connected to standard earth bar/rod. It is used to discharge euipments which was on just before sometime and put off now for maintenance job. It is essential to discharge an equipment as all insulation has a capacitive part and it holds some static charges which may cause shock to working or maintenance personnel when get in touh with the equipment.