Bonding between two buildings

[brizospark]

Working in a factory at the moment

One half of the building is fed from one street, the other from a different supply in a different street

Should the bonding be connected together or kept separate?

 

[Deleted member 9648]

Are there two separate sets of services?.Presumably it used to be two separate buildings?...if so I would bond each service to the applicable incoming supply......Sounds like an Isolation nightmare though.....lots of warning notices at DB's would be appropriate me thinks.
If the supplies overlap within the buildings I would suggest a link between the two MET's would be a good idea to avoid any potential difference between the two earthing systems.

 

[topquark]

Keep them separate, they may be on different phases!!

 

[telectrix]

i would have thought they would be 3 phase supplies. still could come from separate subs. though.

 

[topquark]

Not so bad if they are Tel, otherwise you'd be running 'round sticking up extra warning signs left, right and centre.

 

[brizospark]

they are both 3 phase supplies

 

[brizospark]

used to be 2 separate factories, now the same

 

[topquark]

Do any of the supplies overlap as wirepuller says or are they completely self contained?

 

[brizospark]

they do not overlap as far as im aware but i suppose the potential for them to overlap is there

 

[Engineer54]

You could run in a separate bonding conductor from one MET (say from the original factory supply) to the second supply via a detachable/removable link at the second supply MET. Leave the link open until such time that the supplies start overlapping between the two factories.
Then it's just a case of labeling this link connection at both ends....

This is fairly standard practice where two or more buildings are supplied from separate supplies, that through necessity supply various plant in two or more of those buildings

 

[brizospark]

what dangers would connecting both bonding systems pose?

 

[topquark]

The only danger is in the event of a fault in one of the buildings. When the cpc will have one of the phases present from the other building. In that scenario you may have more than one phase present at a time (in unexpected circumstances .. you'd normally label all likely places). That's assuming that the delivery of each building is in phase sync (which it probably is anyway and) in the worst case would be taking two phases as 180deg out of phase (purely theoretical) ... hence the at worst case double it scenario.

 

[pushrod]

If it is now one building then the structural steel would probs all be linked throughout so my gut feeling would be all the bonding should be linked.

 

[topquark]

If it is now one building then the structural steel would probs all be linked throughout so my gut feeling would be all the bonding should be linked.

If you try getting continuity between adjacent steel structures you'll find a very high resistance (coz the steel is in concrete usually).

 

[pushrod]

If you try getting continuity between adjacent steel structures you'll find a very high resistance (coz the steel is in concrete usually).

Was thinking of big RSJs but i suppose it's probs silly of me to to comment on the building stucture when i haven't even seen lol (it could be brick and wood for all i know)