ADS

When I employ EEBADS I know that every conductive part within a building (that is immovable and/or can be gripped by a human hand) will be at the same potential, therefore if any 'hazardous live' line conductor comes into contact with any conductive part within the building, I can predict an automatic disconnection time not exceeding 0.4 seconds.

That's a bit of an over-generalization, but I'll come back to that in a moment...

So if you've taken away the "earthed equipotential bonding" element, how does "automatic disconnection of supply" actually work?

Nothing's been taken away. The new name of ADS means the same as the old EEBADS.


By way of explanation, consider that not all metallic parts are thought of in the same way - there are exposed-conductive-parts that are Earthed (not bonded) and extraneous-conductive-parts that are bonded (not earthed).


For ADS to work, exposed-conductive-parts (metalic cases of electrical equipment) need to be Earthed - no change there.


Extranous-conducitve-parts (typically water pipes, gas pipes, structural steel) would often be bonded - but not always (not for installations outside of buildings for example) - so the ADS part doesn't rely on bonding of extraneous-conductive-parts for ADS to work - it never has. Bonding has an advantage of reducing touch voltages while ADS operates - and is still required within buildings etc but not in every situation) so ADS is really a better description than EEBADS.


BTW ADS isn't always required to disconnect within 0.4s - for distribution circuits and larger final circuits 5s is permitted - and for TT systems the equivalent numbers are 0,2s and 1s. Bonding extraneous-conductive-parts is especially helpful with the longer disconnection times,


   - Andy,

When I employ EEBADS I know that every conductive part within a building (that is immovable and/or can be gripped by a human hand) will be at the same potential, therefore if any 'hazardous live' line conductor comes into contact with any conductive part within the building, I can predict an automatic disconnection time not exceeding 0.4 seconds.

That's a bit of an over-generalization, but I'll come back to that in a moment...

So if you've taken away the "earthed equipotential bonding" element, how does "automatic disconnection of supply" actually work?

Nothing's been taken away. The new name of ADS means the same as the old EEBADS.


By way of explanation, consider that not all metallic parts are thought of in the same way - there are exposed-conductive-parts that are Earthed (not bonded) and extraneous-conductive-parts that are bonded (not earthed).


For ADS to work, exposed-conductive-parts (metalic cases of electrical equipment) need to be Earthed - no change there.


Extranous-conducitve-parts (typically water pipes, gas pipes, structural steel) would often be bonded - but not always (not for installations outside of buildings for example) - so the ADS part doesn't rely on bonding of extraneous-conductive-parts for ADS to work - it never has. Bonding has an advantage of reducing touch voltages while ADS operates - and is still required within buildings etc but not in every situation) so ADS is really a better description than EEBADS.


BTW ADS isn't always required to disconnect within 0.4s - for distribution circuits and larger final circuits 5s is permitted - and for TT systems the equivalent numbers are 0,2s and 1s. Bonding extraneous-conductive-parts is especially helpful with the longer disconnection times,


   - Andy,