I understand the basic/overall meaning of both, just as well as my electrician co-students. However, I really would like some more precise definitions than what I have been able to find so far. I find it frustrating not having proper definitions, because a) I am constantly in doubt if I am using the terms properly when writing reports or other school work, b) when reading about fx requirements for PE conductors, do those requirements also concern PB (and vice versa).
Here are a few specific questions that I would like settled once and for all if possible.
Are PE-conductors a subset of PB-conductors? You could argue this, since any two objects connected with separate PE-conductors both ending up in the same PE terminal, will be equipotential. Obviously, a PB-conductor directly between the two will have lower impedance and thus be better at achieving equipotential, but still.
Are PB-conductors a subset of PE-conductors? That depends on the definition of PE-conductors, but often PE-conductors are described as if their main characterization is that they allow either an over current detection device or a fault current detection device to shut off the power if an object is electrified. And if that is the characterization, then an equipotential bondings directly between objects will also help make sure that this happens, and in some cases these bonds are the only reason why it happens.
Are they disjoint sets? So that any of these protective conductors is always strictly either a PE-conductor or a PB-conductor?
Or are they overlapping? That means some of these protective conductors are PE but not PB, some are PB but not PE, while some are both. If so, please provide an example.
If possible please provide sources for your answer, and please provide examples.
Best Answer
Simply stated, equipotential bonding is the application of conductive jumpers between two or more conductive surfaces for the purpose of placing all of these surfaces at the same potential.
Earthing or PE-Bonding occurs when the bonded surfaces described above are connected to a Protective Earth or Protective Ground point. Don't confuse PE-Ground with other uses of the term, such as analog ground, signal ground, etc.
Any equipment that is energized to lethal potentials could electrocute a user should a fault occur. By shunting any fault current to PE, the user is protected against electrical shock.
Example 1: A control cabinet with a hinged cover contains circuitry that is energized from the mains. A jumper must be installed to bond the cover to the cabinet to protect the user from any faults in components installed on the cover. Further, the cabinet must be bonded to PE, either through a separate bonding circuit or through the ground core in the power cable.
Example 2: Multiple control enclosures are installed onto bolted support structures, which are welded to a portable skid-mounted compressor system, along with cable tray, instruments, etc. All components that are bolted to their supports must be bonded to a common electrical point; welded members are considered "common" whereas bolted structures and components must be bonded. Finally, the skid, once installed must be PE-Bonded to a protective earth point. With this arrangement, each component has a path back to earth to shunt any dangerous fault current. Also, cable trays are bonded back to earth to protect against a damaged cable that could possibly energize the tray.
The standards I have access to and can reference are: IEC60364, IEC61892-6, NORSOK E-001 & I-001.
Another application beyond lethal fault currents is guarding against electrostatic buildup in an explosive environment. For example, a belt guard that's not bonded to PE could assume a static charge if the belt it's protecting against rubs the guard's surface, creating a possible source of ignition.