My word is my bond

[caprinut]

Do you have bond the copper pipe that holds a compressed air supply around a garage to the earth circuit.

Bert

 

[RWD3M]

Does it have a flexible (ie rubber and non-conducting) connection to the compressor?

 

[mtt.tr]

No, unless it has some connection to earth.

There is a proper calculation to decide but I can't recall it of my head.


@sparkysy @Dave-sparks would probably know.

 

[Hotstuff]

If any service entering an installation can introduce an alternative earth potential, it has to be bonded.

I would honestly doubt that a compressor sitting, probably on a concrete surface, is going to introduce an earthy quality to any metallic airline pipework.

I would imagine that there would be some kind of non-conducting link between the compressor receiver and the airline pipework.

If this pipework does not present with any earth potential, by bonding it, it would probably be raised to neutral potential. It could be argued that it was safer to not bond it, especially if the pipework goes outdoors.

I hope that helps.

 

[sparkysy]

As above, there may be no need to bond it if when testing the ohms reading between the main earth terminal and the pipe is higher than 22K ohms, then it is not considered to be extraneous conductive part so doesn't need bonding!
The pipe unless plastic joints have been used will usually be earthed by the compressors main earth anyway.
So as long as it doesn't enter the ground and come out somewhere else chances are it will be above 22K ohms!
If it's fixed to a metal framed building chances are it is already earthed through the main structural bond.
Hope that makes sense!
Sy

 

[Dave-sparks]

Probably not, Strictly you should test it to see whether it is an extraneous conductive part or not.

To be an extraneous conductive part it would have to be in contact with the ground, so unless it runs underground at all it won't be.

Also:
If it is solidly connected to the metalwork of the compressor it will already be connected to earth via the compressor.

If it is attached to any structural steelwork that will already be bonded and will become bonded through that connection.

 

[sparkysy]

All is explained here, the calculation that @mtt.tr refers to is also on that page.

To Bond or not to Bond

Following on from the Mythbusters article in Issue 73 (November 2018) of Wiring Matters, this article looks at the recent change of the wording in Regulation 411.3.1.2 of BS 7671:2018, and what can be done to determine if a conductive part meets the requirements of an extraneous-conductive-part...

electrical.theiet.org

 

[dobbslc]

22k, you learn something everyday!

 

[caprinut]

Cheers everyone.

Bert

 

[premmington]

Why copper pipe - I been using 16mm nylon pneumatic pipe with push fit fittings.

Are you gonna put an air ring main in...? (it makes all the difference supply wise)

 

[caprinut]

Copper pipe cools the air as it passes through there is a sump just before the regulators they have all ways been dry, I just drain the sump from time to time. I have the compressor on a mezzanine with a drain falling from the tank.

Bert