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Posted By Topic: New housing grid earthing

Mar 18 2020 17:52

Just wondered what most people are using for earthing the “reo” grid in housing now?, welded wricons or are there more products out there now?

Mar 19 2020 09:15

I believe simplest & cheapest is half (or even 1/3) of a normal galv electrode, bent 90 deg, one leg tied to reo and other brought up through bottom plate.
If used as foundation electrode, connection must be accessible for test; so just fit flush box & (labelled) blank plate

Mar 19 2020 09:35

The builders we normally work for normally bring a piece of reo up in the wall and we just chuck an earth clamp on it

Slightly side topic but as you mentioned using it as the electrode in accordance with "concrete foundations of a building or floor slab in contact with the
ground and not impeded by a continuous insulating barrier,
may be used in lieu of an electrode specified in Table 5.2."

How common is it there are continuous insulating barriers? How can you tell?

Mar 19 2020 09:55

why a blank plate, i fit a power point where mine are.

Mar 19 2020 12:27

If it's in a location where a socket or other accessory is useful, fine. Otherwise blank plate.

I don't believe earth clamp directly to untreated steel is compliant with (b) & (d), especially with deformed re-bar.

Mar 19 2020 14:01

Interesting and fair

Normally we don't use it as an electrode which is what those requirements relate too, would doing just a bond that way be acceptable in your opinion?

I've never really thought about it being compliant or not, just the way I got taught and have always been told to do it but I don't disagree about there being better options probably, always down to cost as per usual

It's also the fact that they are trying to eliminate us needing to make a trip before concrete is poured

Mar 19 2020 15:30

while that clause applies specifically to electrode connections, the dsame pronciples apply to bonding - and the same maximum resistance applies.

WRT saving a trip; if you don't attend, how can you be sure of the quality of the many connections? While there's a Note to saying that wire ties are deemed to provide a sufficient connection; has the builder read that; or is he using non-conductive ties for the reo?
There's also the fact that this is PEW; and needs a PL.

I suppose it comes down to how much risk the person signing the CoC is prepared to accept.
Bearing in mind that acceptance of risk should generally result in an increase in remuneration; rather than a decrease. Personally I like to take a few sample test readings before the pour; rather than just trust to luck. A photo of the main in-pour connection is also a good idea. without that, I doubt that the EWRB would accept a claim that the builder was acting "under supervision".

Mar 19 2020 15:55

Yeah, this is true, probably something I need to take a firmer stance on with my employer