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Earth grids and hard drawn copper Vs annealed copper
3

Earth grids and hard drawn copper Vs annealed copper

Earth grids and hard drawn copper Vs annealed copper

(OP)
Hi All
We are building a 132KV/33KV substation.
The designer has specified the conductor for the grid to be 150mm2 uninsulated multistranded HD copper.
The inevitable supply issues has drawn out the response " we have lots of annealed available lets use that"
we have not done so (we'll wait for the spec'd cable).
But it begs the question-
what feature or quality is the designer looking for in a HD conductor
corrosion? strength? surface conductivity - we don't know it could be the phase of the moon

Any ideas or reference would be really appreciated
thanks
Don

ps we have a specified pH and resistivity for the soil and fills if that's helpful

RE: Earth grids and hard drawn copper Vs annealed copper

Hi

Hard drawn copper does a much better job at resisting creep than annealed copper other than that I cannot see why you cannot use the annealed copper.
Is the grid loaded such that it might suffer creep?

RE: Earth grids and hard drawn copper Vs annealed copper

We normally use SD copper because it is easier to install. I know of no advantage to HD copper for an earth grid. There is no tension, so there is no problem with tensile strength or creep.

RE: Earth grids and hard drawn copper Vs annealed copper

don01,
In addition to easy working SD copper has higher conductivity than HD copper means lesser copper weight for the same fault current.

RE: Earth grids and hard drawn copper Vs annealed copper

(OP)
Thanks desertfox, jghrist, Kiribanda
I really appreciate your responses.
It would seem we can give a little push back here and ask to use the available materials
(desertfox, these are laid very loosely in the trench and covered with conductive sand & soil mix
there should be no creep or forces at play )

again thanks very much
I look forward to some of the threads here
Don

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