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North American Network Operators Group Date Prev | Date Next | Date Index | Thread Index | Author Index | Historical Re: Presumed RF Interference
Jon, Peter Dambier wrote: As a time-served electrician... *****DO NOT DO THIS***** - it will kill someone.Cut the ground wire in your power cords but ground the equipment directly to a metal frame. However.... You could try separate earth bonding of each components (ie connecting all the chassis together via a provided grounding terminal using nice thick copper wire), however if there is a significant earth fault even that could be dangerous (think fire) - so get a qualified electrician to do it - if there is a ground fault it will use the chassis and the bonded earths as it's route to ground. Earth faults are often easily detectable by using a digital volt meter (Note: analog volt meters do not work for this unless there is a serious fault). First check for induced and ungrounded 'floating' voltages (any AC or DC voltage above 0.05v should be investigated), then if the DVM is fused, check for any current (amps) between chassis. If you have money to spend before investigation find out if the building has a grounding stake and if not add one... A couple of meters of copper stake which will be connected to either the armoring of the supply cable (TN-S) or to the incoming return cable and installation earth PME (TN-C-S) - likely based what someone else in this threat said. In either type of grounding scheme the structure metal frame could (and should) be grounded (esp if exposed) which is likely to cause the phone RF signal drop. A faulty bonding in the structure (esp as it is steal) can also provide for some interesting ground faults as it is not uncommon to provide localised grounding to building frames. (In the UK where I served my apprenticeship, we were required to provide earth bonding to the copper plumbing system, additional bonding at every exposed fitting - this caused a few issues when plumbers first starting using PVC pipes)... All this said with the faults appearing with no external power and with just UPS supply, ground faults really do not 'fit' the problem - however if a generator is used also, you are in an IT type installation (electrical term 'IT' not 'Information Technology' ;-)) and will have to have a grounding stake on site. Please note, I am trained from the UK - laws and regulations change from country to country - get a local qualified/licensed sparky to do the work or assist you. Regards, Mat
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