I'm always getting calls from people who want to plug thier new computer in, and can't decide into what. I've called the maker's tech support many times, with mixed results.
Most want grounding, some will ask for a GFI to replace a 2-wire receptacle, a few want a dedicated circuit,very few want an Iso-ground. On the bizzar side,one chain i service insists on iso-grounds to the closest sub-panel ( I really think that guy just likes to walk around saying "ISO-Grounds") , and i did have an individual insist on a seperate ground rod some years ago.
Enter the UPS & or Power conditioner man, and you can apparently throw out that last paragraph.
It's my sense that there is a little less hoo-haa on the subject, now that computers are more refined, and cost less than they used to.
My Q is how do the rest of you guys in the field deal with this???
I think that We, "as a trade", I mean the guys in the trenches may have a better grasp on the fundamentals of gounding than the "Theorists" that specify IG and mean a grounding rod alone and no bonding of the neutral in a 3phase Y transformer. They must teach that in MIS school, I have no Idea where they get that from.
Scott, maybe you, as an 'EE type' can give us some insight into this rationale?
Re: ISO-Grnd or ISO-circuit#76483 02/10/0109:11 AM02/10/0109:11 AM
I think that the reason there are so many problems with "grounding" is the choice of the word itself. 99% of what we call "grounding" is really bonding. By using the word "grounding" many people in the trade automatically start to think about a connection to earth. The word grounding should be reserved for the grounding electode system and grounding electrode conductor, everything beyond that is bonding. Don(resqcapt19)
Re: ISO-Grnd or ISO-circuit#76485 02/10/0101:17 PM02/10/0101:17 PM
Got a troubleshooting call myself from a local pharmacist. One of their computers is crashing and the 'puter guru insists that it must be a power quality problem.
I don't have an oscilloscope, so bear with me here.
The voltages fluctuate normally between 119 and 121 volts, but occasionally will drop suddenly to 114 and build back up. I realize that the voltages are within "normal" ranges, but does the sudden drop point to anything? Nothing that we know of seems to correlate with the voltage drop by a machine turning on automatically, etc.
Checking the current was more bizarre... it fluctuated rapidly between 3 and 15 amps with every imaginable number randomly appearing between. The computers, routers, hubs and printers were on but idle at this time.
All other circuits in the 120/208V 3 phase panel showed normal fluctuations in voltage and current. The voltage was steady on the questionable circuit on the line side of the breaker, but fluctuated as described above at the receptacles.
Would ISO grounds, isolating the neutrals from 4-wire "networks" to each leg having it's own neutral, and/or UPS (or line conditioners) help in this circumstance?
-Virgil Residential/Commercial Inspector 5 Star Inspections Member IAEI
Re: ISO-Grnd or ISO-circuit#76487 02/11/0111:35 AM02/11/0111:35 AM