Extraneous conductive parts

[Ian1981]

Hi all.
Looking for opinions on here.
I’ve identified during an eicr that a dry rise pipe used for firefighters in the building is in fact an extraneous conductive part and that it is not bonded back to the MET.
However what I’m questioning is it’s accessability to be touched in the event of a fault.
Pipework is installed in boxing with a key for an access panel for the riser water inlet to be used for the firefighters.
Only person with access is the building manager.
What’s people’s opinions does it require protective bonding or is it deemed not accessible to touch and that’s the end of the matter?
It’s worth pointing out bs 7671 doesn’t mention the fact it needs to be accessible however it’s common sense that says it needs to be if your going to be in contact during a fault between say an exposed conductive part and said pipework.
Thanks

To add the dry riser pipe comes up from the floor in metal and is separate from the cold water pipe entering the building in plastic.
A completely different service it seems.

 

[telectrix]

no i'm confused ( doesn't take much). in OP's post #4, he says:
Testing from the MET or rather the source of earthing to said pipe.
Main earthing conductor disconnected from source earth
IR set to 500v reading of 0.00 Mohms
Also no continuity between said pipework and a known earth source
so... riser is 0.00 M to MET and no connection to earth. that says it's not extraneous.?????

 

[Deleted member 26818]

no i'm confused ( doesn't take much). in OP's post #4, he says:
Testing from the MET or rather the source of earthing to said pipe.
Main earthing conductor disconnected from source earth
IR set to 500v reading of 0.00 Mohms
Also no continuity between said pipework and a known earth source
so... riser is 0.00 M to MET and no connection to earth. that says it's not extraneous.?????

The OP has apparently changed his mind.

 

[DPG]

Maybe some of the wording wasn't clear. No need for things to get offensive though.

 

[Richard Burns]

no i'm confused ( doesn't take much). in OP's post #4, he says:
Testing from the MET or rather the source of earthing to said pipe.
Main earthing conductor disconnected from source earth
IR set to 500v reading of 0.00 Mohms
Also no continuity between said pipework and a known earth source
so... riser is 0.00 M to MET and no connection to earth. that says it's not extraneous.?????

I think perhaps the post might be worded better as

Testing not from the MET but from the source of earthing, whilst it is disconnected from the MET, to said pipe.
IR set to 500V reading 0.00MΩ.

When testing from a known earth internal to the installation to the said pipework there was no continuity.

This is what has been said in post 19.

The pipe is (presumably) buried in the ground and so has very good contact with the ground and therefore shows up as an effective earth rod. However the pipe according to the continuity readings is not connected to the installations earth wiring i.e. it has not been bonded nor has it got a connection with any cpc.
Therefore the pipe is at earth potential but the issue is does it introduce that potential into the installation.

 

[telectrix]

Therefore the pipe is at earth potential but the issue is does it introduce that potential into the installation.

or does it introduce an earth potential into the building? and if so, can it be touched? that seems to be the £64,000 question.

 

[Devonchris]

A "dry riser" is a vertical pipe that usually starts at ground floor level and has an outlet on each floor. Its purposes is to allow firefighters to connect at ground level and the fire level without having to run hose in stairwells.

At no point would it enter the "ground". Effectively, its just a bit of metal within the building. Unless someone has made some sort of connection, then I would be surprised if it tests as extraneous.

 

[Which One’s Live?]

...that seems to be the £64,000 question.

I nearly fainted then; I thought that was a job quote!!

 

[bigspark17]

In relation to the OP i think @Devonchris is right and at no point should that dry riser be in the ground apart from fixed to it, but the OP is the man on the job and an experienced one at that.

 

[johnduffell]

could be explained maybe someone else in the building has already bonded it to their MET? making it an ECP for all other equipotential bonding zones it enters

 

[ipf]

could be explained maybe someone else in the building has already bonded it to their MET? making it an ECP for all other equipotential bonding zones it enters

Shut it down Marvo.
It's getting ridiculous.

 

[Ian1981]

The key point of the original question I think is is there an exposed conductive part, a live part (even if covered), or another bonded extraneous conductive part within 2.5 m of the hatch giving access to the riser.
The majority of the riser is inaccessible and therefore cannot introduce a potential; if the access hatch is not near any conductive part that may become live and can be simultaneously touched by a person or livestock, then the part at the hatch will also not be able to introduce its potential into the installation and bonding would not be necessary.

I think what Ian1981 is saying about measurements is as described in the below diagram. The riser is connected to true earth, but not connected to the installation protective conductors.
View attachment 43000

Didn’t realise it’s thread is still running but yes Richard you are correct

 

[Ian1981]

I think perhaps the post might be worded better as

Testing not from the MET but from the source of earthing, whilst it is disconnected from the MET, to said pipe.
IR set to 500V reading 0.00MΩ.

When testing from a known earth internal to the installation to the said pipework there was no continuity.

This is what has been said in post 19.

The pipe is (presumably) buried in the ground and so has very good contact with the ground and therefore shows up as an effective earth rod. However the pipe according to the continuity readings is not connected to the installations earth wiring i.e. it has not been bonded nor has it got a connection with any cpc.
Therefore the pipe is at earth potential but the issue is does it introduce that potential into the installation.

Correct again

 

[Ian1981]

A "dry riser" is a vertical pipe that usually starts at ground floor level and has an outlet on each floor. Its purposes is to allow firefighters to connect at ground level and the fire level without having to run hose in stairwells.

At no point would it enter the "ground". Effectively, its just a bit of metal within the building. Unless someone has made some sort of connection, then I would be surprised if it tests as extraneous.

The dry riser comes out of the ground all metallic in construction and does introduce an earth potential.
It is a separate service entering the building and not in anyway connected to the main buildings water supply.

 

[johnduffell]

Shut it down Marvo.
It's getting ridiculous.

don't get it? was it a joke and I'm being thick or just you quoted the wrong post?

 

[bigspark17]

don't get it? was it a joke and I'm being thick or just you quoted the wrong post?

Agree!! If you dont like the post just ignore it!!