Discuss Using rebar as earthing. in the Electrical Wiring, Theories and Regulations area at ElectriciansForums.net
I didnt realise that concrete would conduct so well compared to soil.
Thanks.
Its called "Ufer earthing". Concrete is a better conductor of electricity than soil, and it makes sense to insert your earth rod, or mesh (ie rebar) into it. As rebar is used anyway, its silly not to make use of it. The concrete will also have a much greater surface area than a rod or tape. I beleive that lightning can cause the concrete surrounding the rebar to crack, however in this country, this would not put me off.
At work, we install big generators onto concrete plinths, that our company is responsible for providing. The rebar is not bonded down, and we have to use earth rods to tie the genny to ground potential. Im trying to convince the engineer
to use Ufer earthing, as i think it would be more cost effective, and easier.
Ufer earthing works best with a large area of slab/footings. A generator or transformer plinth would in all probability, depending on what depth the plinth is in the ground, need a supplementary earth ring around the plinth. Also depends on what your using as your max Ra value. .....Please tell me it's not 200 ohms??
The engineer wants below 20 ohms, and ive managed 4
The reg. (542.2.3 (v))does say the rebar should be welded.
Does that mean it can only be used if it is planned and intended to be used as an electrode?
The reg. doesn't say 'should' - that was me, sorry.
542.2.3 Suitable earth electrodes shall be used...
(v) Welded metal reinforcement of concrete (except pre-stressed concrete) embedded in the ground.
Usually tied together with stainless steel wire.
As for connecting to it: drill into the top of a piece purposely left sticking out, tap a thread then connect with a ring crimp and a bolt, cover with grease to stop rusting. Is how I'd do it.
Not what you would term "light" reading!
It explains some of the things I've been doing since starting in the industry.
Also an appology to Herb Ufer for keeping on spelling his name wrong.
Reply to Using rebar as earthing. in the Electrical Wiring, Theories and Regulations area at ElectriciansForums.net
We get it, advertisements are annoying!
Sure, ad-blocking software does a great job at blocking ads, but it also blocks useful features of our website. For the best site experience please disable your AdBlocker.