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isolators for earth bar or not?

Tom D

Can someone explain why Erath bar is sitting on an isolators and not directly on the backplate creating solid earthing connection to the whole box/panel/enclosure?

I remember in my old place we bolted in PE bars directly on a backplate but in my present company we use isolators.

Is this normal procedure or only necessary in some circumstances?

Cheers

Parents
  • 0

    Yes, we do provide Isolators while installing the earth bar and there are mainly a few reasons

    1. It will avoid unintended earth loops within the panel,  When you mount an earth bar directly to a metallic panel or structure without insulation, it may create multiple earth paths unintentionally, which could lead to earth loops, where current flows through unintended grounding paths.

    2. During maintenance or commissioning, sometime we may need to test the continuity or resistance of the earthing system. in case the earth bar is in direct electrical contact with the cabinet, it's difficult to isolate and measure accurately. 

    3. This also will help in corrosion prevention in humid area, between earth bar & metal Cabinet.

    4. For Larger voltage panels this could also help Insulation from Fault Currents flowing through metal body, This protects personnel and equipment from electric shock or damage due to unexpected touch voltages.

Reply
  • 0

    Yes, we do provide Isolators while installing the earth bar and there are mainly a few reasons

    1. It will avoid unintended earth loops within the panel,  When you mount an earth bar directly to a metallic panel or structure without insulation, it may create multiple earth paths unintentionally, which could lead to earth loops, where current flows through unintended grounding paths.

    2. During maintenance or commissioning, sometime we may need to test the continuity or resistance of the earthing system. in case the earth bar is in direct electrical contact with the cabinet, it's difficult to isolate and measure accurately. 

    3. This also will help in corrosion prevention in humid area, between earth bar & metal Cabinet.

    4. For Larger voltage panels this could also help Insulation from Fault Currents flowing through metal body, This protects personnel and equipment from electric shock or damage due to unexpected touch voltages.

Children
  • 0 in reply to Anoop Singh
    Anoop Singh said:
    grounding paths

    This term is only used in US and Canada. In standards based on IEC, CENELEC and British Standards, the correct terms are 'earthing' and 'bonding', just so we don't get confused.

    Anoop Singh said:
    4. For Larger voltage panels this could also help Insulation from Fault Currents flowing through metal body, This protects personnel and equipment from electric shock or damage due to unexpected touch voltages.

    This is a good point ... although really it may well be that the panel's enclosure isn't perhaps of sufficient thickness to carry the fault current. If using armoured cables, for example, we often have the parallel path anyway via the bonding to the accessible parts of the metallic enclosure. I guess the point here, is that we can help control the fault current flow (and hence potential differences) better by insulating the earth bar, and providing larger cross-sectional area circuit protective conductors to the banjo/earthing nuts of the SWA gland, and smaller cross-sectional area bonding conductors to the enclosure.

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