Equipment bonding jumpers are they always necessary
Download
1 / 23

“Equipment bonding jumpers: are they always necessary?” - PowerPoint PPT Presentation


  • 76 Views
  • Uploaded on
  • Presentation posted in: General

“Equipment bonding jumpers: are they always necessary?”. Massimo Mitolo, Senior Member, IEEE. “Equipment bonding jumpers: are they always necessary?”. “ Equipment Bonding Jumpers” are equivalent to: “Protective Bonding Conductors” ( PE ) as per IEC 60364 :

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha

Download Presentation

“Equipment bonding jumpers: are they always necessary?”

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


“Equipment bonding jumpers: are they always necessary?”

Massimo Mitolo, Senior Member, IEEE


“Equipment bonding jumpers: are they always necessary?”

“Equipment Bonding Jumpers” are equivalent to:

“Protective Bonding Conductors” (PE) as per IEC 60364:

Maintain continuity of the equipment grounding path.

ProvideProtective Equipotential Bonding.


Exposed-conductive-part (ECP)

Conductive part

forming part of electrical equipment

which can betouched (even if out of reach)

which is not live

which may become live when basic insulation fails.


Exposed-conductive-part (ECP)

ECPs shall be bonded to ground

so that fault current is allowed to flow to ground, permitting the protective device to promptly disconnect the supply.

Grounding is the 2nd level of protection, the basic insulationbeingthe 1st.


Exposed-conductive-part (ECP)

Piece of equipment with “double” (or reinforced) insulation (Class II equipment), is not considered an ECP and

shall not be connected to a PE.

(!!NEC art. 250-110 Exception n. 3!!)

Additional insulation is the 2nd level of protection

Symbol:


Exposed-conductive-part (ECP)

A conductive part which can be energized just because in contact with an ECP, is not an ECP.

(it is not required to be grounded, then!)


Extraneous-conductive-part (EXCP)

Conductive part

not forming part of the electrical system (e.g. piece of metalwork)

liable to introduce a “zero” potential

or an arbitrary potential into the premises.


Extraneous-conductive-part (EXCP)

EXCPs shall be bonded to ground

Equipotential connections between ECPs and EXCPs will significantly reduce the magnitude of their potential difference under fault conditions.

(Necessary but not sufficient condition!)


Extraneous-conductive-part (EXCP)


Extraneous-conductive-part (EXCP)

It’s an EXCP if less than:

1000 Ohms

(200 Ohms)

(based on the definition of permissible body current and body resistance of a “standard” person

As per IEC 60479-1)


Where do you find PEs?

6 possible cases:

  • PE in equipments

  • PE among ECPs

  • PE among electrostaticly chargedobjects

  • PE for Lightning Protection Purposes

  • PE among ECPs and metal parts

  • PE among ECPs and EXCPs


1. PE in equipments

Clear path to ground = Low resistance PE


1. PE in equipments


2. PE among ECPs


2. PE among ECPs


3. PE among electrostaticly charged objects

The metal object is isolated from ground (resistance to ground greater than 1 MOhm)

+

Any mechanism for generating electric charges exists

+

An explosive atmosphere is present


4. PE for Lightning Protection Purposes

Overvoltages are induced in any closed loop with possible electric discharge through the gaps


5. PE among ECPs and metal objects


5. PE among ECPs and metal parts


5. PE among ECPs and Metal objects?


6. Among ECPs and EXCPs

Equipotential connections between ECPs and EXCPs will significantly reduce the magnitude of their potential difference under fault conditions.


CONCLUSIONS

Basic investigation on the nature of conductive parts is necessary, in order to assess in which category they fall (ECPs or EXCPs).

Only ECPs and EXCPs shall be considered for grounding.


“Equipment bonding jumpers: are they always necessary?”

Any questions?


ad
  • Login