Possible causes of static build up on equipment?

Question

I have differnet equipment at my work site. I found yesterday the the power is wired differently one on them. All the systems run on 100VAC 1 phase. The system that has the VAC ground running to the power pull has not sign of static problems. The other system have VAC ground connect to the chassis ground. Would this be the cause of my static problem.

Answer 1

What you are describing is NOT static. It's unsafe return current running to a high resiswtance ground- IOW, powerline shock. In the event of a water puddle on the floor, your company could end up paying for someone's death. My question is, where the heII was the electricians head when he wired this shop IN VIOLATION OF NEC?

Answer 2

Grounding is a rich subject in EE. Here is the best way to do it, in my opinion (also the National Electrical Code): Everything can trace its ground to the ground pin on the service outlet. Chassis should connect to that ground (unless you built it yourself and didn't know the rules, that will be the case. Just use an ohmmeter between the ground pin on the power plug and chassis. Should show about zero Ohms.) So, the connection path should be (a) the ground pin at the AC receptical is grounded through the mains supply and then (b) the ground pin on the connector and ground wire in the cord from the outlet to the equipment carries the ground to the equipment and then (c) the chassis of the equipment is connected to the ground wire in the electrical cord and, further, if there are any connectors on the equipment that offer something line a ground terminal or a shield connection, that should be connected to the chassis ground (note here that some very sensitive instruments "float" the shield of coaxial connectors on front panel. If you look at the schematic, you will find that there is a path, perhaps thruough resistors, to chassis ground.)

The best advice is to lose the word "ground" from your electrical vocabulary and substitute "common" or "return" instead. That will remind you that every such connection is a part of a "circuit" and may be shared with other equipment that may "noise it up". Ground is what prevents you and your desk and your dog and your car from falling to the gravitational center of the planet. We connect things to it so that there will not be a potential difference large enough to be an electrical shock hazard.

Answer 3

I couldn't really follow you decription of the grounding. But it doesn't sound like a static problem but a grounding problem. I have found that it is best to pull a ground wire from the source all the way to the equipment. Relying on conduit cabinets ect. to continuously ground equipment doesn't always work even if it does meet the code. All that has to happen is for a piece of conduit to come loose and you've lost the grounding.

Answer 4

All grounds should totally common and only connect to the neutral at the transformer. If your ground and neutral in multiple places u will have your ground in parallel with your neutral . If u Have current flowing in your safety ground u got problems and it is dangerous and not static charge.
One other thing is some of the older equipment have a small cap from one side of the AC to chaise ground. Take the cap out and replace with a MOV .