bonding to shower in pre-fab offices

[academy]

Hello all,

Recently tested some office accomadation units for a building site (the type that come as individual bays with own db and then get bolted together to form an open plan office and all db's for each bay run back to a main db for each floor). One area had four showers supplied from 30ma rcbo's at the main board. The water to these showers comes up in plastic polypipe to a tank with a pump for the showers. It is then in plastic on the otherside of the pump for about 3 meters and then joins the copper pipework for the showers. Wander lead method gave a reading of 0.21 ohms from the copper pipe adj to shower back to the earth bar for that level with no signs of any bonding.
Should I recommend that bonding is installed to try and get the reading down to 0.05 (what my head is telling me) or as its fed in plastic and on an rcbo let it go (as I know the client will suggest, apparently I am a bit fussy!)

Thanks in advance

 

[IQ Electrical]

Hello all,

Recently tested some office accomadation units for a building site (the type that come as individual bays with own db and then get bolted together to form an open plan office and all db's for each bay run back to a main db for each floor). One area had four showers supplied from 30ma rcbo's at the main board. The water to these showers comes up in plastic polypipe to a tank with a pump for the showers. It is then in plastic on the otherside of the pump for about 3 meters and then joins the copper pipework for the showers. Wander lead method gave a reading of 0.21 ohms from the copper pipe adj to shower back to the earth bar for that level with no signs of any bonding.
Should I recommend that bonding is installed to try and get the reading down to 0.05 (what my head is telling me) or as its fed in plastic and on an rcbo let it go (as I know the client will suggest, apparently I am a bit fussy!)

Thanks in advance

Are all circuits in the location 30mA RCD protected?

 

[academy]

Well in each cubicle it's only the shower and a class 2 (mounted outside of zones as well) light fitting

 

[Deleted member 9648]

You need to decide if the pipes are an extraneous conductive part.......if they are and ALL circuits within the shower room are not RCD protected then supplementary bonding will be required.
If copper pipe is entering the shower area from outside of the shower area you will have to assume it is extraneous......if plastic is entering the shower area and the only copper is within the shower area it will not be extraneous.

 

[IQ Electrical]

If the reading is 0.21 Ohms from the copper to the MET then there's no doubt it's extraneous.

 

[Deleted member 9648]

If the reading is 0.21 Ohms from the copper to the MET then there's no doubt it's extraneous.

Not necessarily...some shower units have an internal link from the earth terminal to the pipe connection.........it really depends on whether copper is coming into the shower area from outside the shower area.If the copper is wholly within the shower area it is unlikely to be extraneous.

 

[tonys]

I thought the reading of 0.05 ohm was the max resistance between extraneous conductive parts and exposed conductive parts with in the shower area?

Obviously if they both exist.

 

[academy]

Thanks for the replies so far gents, the thing is it's not to far back to the db so I may just code 2 it as it wouldn't be the hardest thing for them to correct ( or me). On this particular floor of the accommodation there is only the one db that feed each circuit in each individual bay. In the bay there are the four shower cubicles, other than the class 2 fittings there are no other circuits. The polypipe travels from outside up to this floor and into the tank with the pump and then after about 3 meters joins the copper pipe outside the room containing the four cubicles. Couldn't see any earth links from the shower to the pipe so was expecting a really high reading and not to have to do anything to it to be honest, each shower is run in 10mm with an r1+r2 of 0.04 (from memory am in the van at the minute)

Thanks again