What about shielded power cables.

Merry Christmas
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Gentlemen:

Each year my employer loses thousands of dollars worth of electronic
equipment due to lightning related phenomenon. We are planning a
comprehensive review of our grounding, bonding, shielding and surge
suppression systems.

My question is - would we benefit from feeding our equipment using
shielded power cables?

The equipment consists of traffic control systems which are fed via
a pretty typical single phase 120 VAC supply disconnect on a pole.

The only shielded power cable I have been able to locate is primarily
intended for VFD's or instrumentation applications.

Would this be a waste of money? Why wouldn't shielded power
conductors be a good idea? If the shield was terminated in the panel
at the single point ground bus, would it not help to immunize the supply
from the effects of transients?

I suspect this makes no sense because the use of shielded power
cables does not seem to be in wide useage except possibly for high
voltage transmission.

Any information or suggestions would be greatly appreciated.

Thanks
 
DANIEL LAWLOR said:
Gentlemen:

Each year my employer loses thousands of dollars worth of electronic
equipment due to lightning related phenomenon. We are planning a
comprehensive review of our grounding, bonding, shielding and surge
suppression systems.

My question is - would we benefit from feeding our equipment using
shielded power cables?

The equipment consists of traffic control systems which are fed via
a pretty typical single phase 120 VAC supply disconnect on a pole.

The only shielded power cable I have been able to locate is primarily
intended for VFD's or instrumentation applications.

Would this be a waste of money? Why wouldn't shielded power
conductors be a good idea? If the shield was terminated in the panel
at the single point ground bus, would it not help to immunize the supply
from the effects of transients?

I suspect this makes no sense because the use of shielded power
cables does not seem to be in wide useage except possibly for high
voltage transmission.

Any information or suggestions would be greatly appreciated.

Thanks


Im sure sheilded cable wouldnt hurt, but help im not sure. In your situation, it sounds like there werent properly bonded ground rods to help with the lightning, and yes you definitely need surge suppression outlets. The surge suppression outlet should help with most of them .
 

charlie tuna

Senior Member
Location
Florida
there must be another reason your boss is loosing this much equipment. incoming power my be "dirty" or some kind of an intermittent problem after hours??? get a qualified contractor to set some data recorders and let them run for at least a week. and i'm sure he has power conditioners on the important equipment--right????
 

drbond24

Senior Member
I really don't think that using shielded cable is going to help with lightning problems. The shield just confines the electromagnetic field around the cable so it can't interfere with other cables around it; a lightning surge is so much greater than normal conditions that the shield wouldn't be any help there.
 
DANIEL LAWLOR said:
Gentlemen:

Each year my employer loses thousands of dollars worth of electronic
equipment due to lightning related phenomenon. We are planning a
comprehensive review of our grounding, bonding, shielding and surge
suppression systems.

My question is - would we benefit from feeding our equipment using
shielded power cables?

The equipment consists of traffic control systems which are fed via
a pretty typical single phase 120 VAC supply disconnect on a pole.

The only shielded power cable I have been able to locate is primarily
intended for VFD's or instrumentation applications.

Would this be a waste of money? Why wouldn't shielded power
conductors be a good idea? If the shield was terminated in the panel
at the single point ground bus, would it not help to immunize the supply
from the effects of transients?

I suspect this makes no sense because the use of shielded power
cables does not seem to be in wide useage except possibly for high
voltage transmission.

Any information or suggestions would be greatly appreciated.

Thanks

Sounds like a surge arrester solution, but you would need to be more specific on the construction of the unit or units you are trying to protect. Are these standard traffic signal control boxes on the roadside?

Shielded cable is used to minimize, along with twisted pair, of interference on low level signal wiring, such as 4-20mA, 0-10VDC, etc.

Induced power surges on power lines are a diffrent kettle of fish.

No lighting damage potential can be completely eliminated except by a self contained Faraday cage where all the equipment is inside of it and no leads are in or out. Even then.......some say:cool:
 
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