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| Thread ID: 63854 | 2005-11-25 00:16:00 | Grounding precautions for h/w installs | bardin (1950) | Press F1 |
| Post ID | Timestamp | Content | User | ||
| 407243 | 2005-11-25 00:16:00 | Hi all, If you remove the pwr cable from the case before you begin your work on the components, even if you attach an anti-static wriststrap...where does it ground to? Doesn't it need to be plugged in at the wall (but turned off) for the PC to be grounded...? Or is there enough grounding provided by the case itself, perhaps through the PSU? Think I read years ago in UPGRADING AND REPAIRING PCs (the hardware bible I believe), that ideally you want to have a specially-modified pwr cable that only has the longer, earth, pin...? But who ever sees anyone using them? I work in IT, have CBC, A+, MCSA etc, but I don't often see people using ESD precautions at all... Cheers, Brendan |
bardin (1950) | ||
| 407244 | 2005-11-25 00:42:00 | Yes it should be plugged into the wall. Or I also have an antistatic mat which is connected to earth on a power cord and plugged in. For those jobs without a case... |
pctek (84) | ||
| 407245 | 2005-11-25 00:46:00 | Keeping the power cable connected to the wall, but with the power SWITCHED OFF is the ideal. But as Godfather pointed out in another thread recently, it's acceptable to just have your wrist strap attached to the case, unplugged. The reason being that what you want is to have your level of static in your body equalised with the static in the case and components. Therefore grounding in itself isn't strictly required. |
Greg (193) | ||
| 407246 | 2005-11-25 01:19:00 | The last lot of ram I installed in someone's case. Dick Smith suggested (or rather demanded) that we get an antistatic wriststrap, since we got the ram from them. Which was rather pointless. I didn't use it in the end, and took the wriststrap back for a refund 5 mins later lol. |
Speedy Gonzales (78) | ||
| 407247 | 2005-11-25 01:47:00 | . . . and if you had taken the RAM back 10 minutes after that, looking for a replacement ("It doesn't work") , what would DSE have said? Normal care is enough protection . Usually . If you want to be sure, use a wriststrap . If you want to be really sure, use an antistatic mat, properly earthed, and a wriststrap (or ankle strap) . Antistatic mats are really needed when you are working with individual components, when you can't avoid touching the leads . Memory sticks, and interface cards, which you can handle without ever touching the connections are pretty safe if you make a habit of touching the case before picking them up . You can make your own earthing cord . Just connect an earth wire to a three pin plug and put a croc clip on the other end . Or cut off the end of a moulded cord and strip it . Cut off the phase and neutral wires and add a croc clip to the green/yellow wire . Onlookers, the ones with eyes in their fingertips so they can't see without touching shiny bits (especially gold plated bits) are a menace . They are the ones for whom I always kept an 8 microfarad capacitor charged to 300V on the bench . |
Graham L (2) | ||
| 407248 | 2005-11-25 03:01:00 | I'd add a comment re Graham's earthing cord, for added safety, include a resistor in the line, about 470kΩ to 1MΩ. Then in the event that somehow you come into contact with raw 230v mains with one hand, and you are touching 'earth' with the other, then the current flow through the heart will not be lethal. :cool: Wrist straps already have a resistor built in. |
Terry Porritt (14) | ||
| 407249 | 2005-11-25 03:31:00 | Oops ... trying to keep it simple, I oversimplified. The cord I described would be to earth the case of a computer, in the same way as its normal power cord; not to earth you by connecting the clip to your navel ring, or other body piercing accessory. The commercial antistatic straps do have a resistor, of course. A while ago I wondered just how conductive the antistatic mat was. I tried with a 500V Megger. No reading. No, my Megger wasn't faulty. My wrist strap read 1M. A 20M resistor read 20M. It turns out that antistatic mats have a resistivity measured in very high powers of 10. They are really anti "static" mats. |
Graham L (2) | ||
| 407250 | 2005-11-25 03:46:00 | You can make your own earthing cord . Just connect an earth wire to a three pin plug and put a croc clip on the other end . Or cut off the end of a moulded cord and strip it . Cut off the phase and neutral wires and add a croc clip to the green/yellow wire . Or shove a long nail down the earth part of an extension cord . Attach clip to nail . |
pctek (84) | ||
| 407251 | 2005-11-25 03:56:00 | Earthing should be done with proper connections. Screw terminals or soldering qualify. Sharp objects pushed into cables don't. "Earthed" objects at 230V can add interest to life. Briefly. | Graham L (2) | ||
| 407252 | 2005-11-25 06:32:00 | Hi all, If you remove the pwr cable from the case before you begin your work on the components, even if you attach an anti-static wriststrap...where does it ground to? Doesn't it need to be plugged in at the wall (but turned off) for the PC to be grounded...? Or is there enough grounding provided by the case itself, perhaps through the PSU? Many power plugs don't have the earth pin on them anyway so it is pointless to leave it pluged in. Just take good pre-cautions by not doing it carpets that you slide your feet over to build up a charge. Grab the case to discharge any charge you may have on you already and bring them to the same potential. I have done many memory, CPU, MB and card changes and have never suffered a failure yet following this. |
Big John (551) | ||
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