[CampboundFZE]

Hey Gang, I need your thoughts on this.
bonding of a Gland on armored cable is done largely for reducing the "touch potential" that can be induced into the Armour of an AC cable. Cables under 400 amps are typically bonded at both ends, while over 400 amps are only on one end. What I am questioning is the bonding of glands on signal cables (instrumentation), now if there was "clean earth" availability I wouldn't even pose this, but bonding the gland to the same earthing system used by large motor systems seems to be in contrast to bonding to eliminate "Noise".

in addition, if a massive fault were to occur, it is possible to distribute a portion of that fault current to the critical ESD systems is it not.

Nothing I can see in the wide world of Google, clearly points out why we would bond the signal cabling to the "Dirty Earth" system. I'm looking for real answers here guys as the way bonding is done over here in the middle east is ugly and expensive.

Cheers

 

[HARRY304E]

Hey Gang, I need your thoughts on this.
bonding of a Gland on armored cable is done largely for reducing the "touch potential" that can be induced into the Armour of an AC cable. Cables under 400 amps are typically bonded at both ends, while over 400 amps are only on one end. What I am questioning is the bonding of glands on signal cables (instrumentation), now if there was "clean earth" availability I wouldn't even pose this, but bonding the gland to the same earthing system used by large motor systems seems to be in contrast to bonding to eliminate "Noise".

in addition, if a massive fault were to occur, it is possible to distribute a portion of that fault current to the critical ESD systems is it not.

Nothing I can see in the wide world of Google, clearly points out why we would bond the signal cabling to the "Dirty Earth" system. I'm looking for real answers here guys as the way bonding is done over here in the middle east is ugly and expensive.

Cheers

Look at article 800.100 in the 2014 NEC.

Welcome to the forum...:thumbsup:

 

[NacBooster29]

It is typical on signaling cables to bond only one end. Usually the end at the head end. And isolate the field end. I'm not sure of your particular situation.

 

[CampboundFZE]

Thanks Harry,
Communication cables can carry up to 75 volts, I am referring to 4-20ma signal cables with no potential of spark introduction, under normal installation and operation function

NEC, CEC, NFC are all derivatives from IEC, I can not extract clear rational from any of these codes and all make reference to AC power cables.

The closest rational I have found is to reduce "Noise Potential" which would interfere with the signal and provide false indication at the CP or instrument itself, which I fully understand. But in this case, I am concerned of the potential interference caused by connecting my sensitive instrumentation systems to my AC/DC 400 volt systems via bonding conductors.

I would ultimately like to see a dedicated earth or what we call a "clean earth" installed, but am looking now at the lesser of two evils, attaching to the "Dirty earth" or not.

Yes Nac, attaching the "Drain" wire within the cable is done this way for sure, but what I am referring to is the the gland bonding. In countries outside of North America, a bonding ring is installed between the gland and the cable entry point, this ring is then bonded via a copper conductor to the earthing system (Looks horrible, but eliminates touch voltage potential on AC cables) in North America, we use Tech cable (Big difference) as well as all or most of our cables have an internal earth wire, making bonding much easier and less expensive.(people over here steal the bonding jumpers faster than we can install them).

 

[chewy]

When I did them we cut the drain off and used heatshrink over the end to isolate the drain at the field end. Ive only ever worked with it once thusfar.