Neher McGrath Typical Value for Concrete
Neher McGrath Typical Value for Concrete
(OP)
I think it is interesting that when doing underground temp calcs, that most use 55 for the Rho of concrete, because it is printed as a typcial value in the NEC.
The "father" of underground duct bank calcs wrote in his paper in 1957 (AIEE Paper 57-660, Table IV) that the typical value is 85.
Any ideas why it has changed? Maybe a simple typo? Has anyone had their concrete tested for thermal Rho?
The "father" of underground duct bank calcs wrote in his paper in 1957 (AIEE Paper 57-660, Table IV) that the typical value is 85.
Any ideas why it has changed? Maybe a simple typo? Has anyone had their concrete tested for thermal Rho?






RE: Neher McGrath Typical Value for Concrete
RE: Neher McGrath Typical Value for Concrete
Reality means you live until you die. The real truth is nobody wants reality.
RE: Neher McGrath Typical Value for Concrete
I take excepton to your signature, though. To paraphrase Pastis,
We're born, we die. But in between we got scotch, cigars, and donuts!
Best to you,
Goober Dave
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RE: Neher McGrath Typical Value for Concrete
The same problem with Earth Thermal Resistance. NEC= 90 C cm/W ;IEEE 835 60,90,120 C cm/W ;VDE 298 07-2.5 Km/W
I think NEC is so generous since it about domestic [or commercial or industrial facilities] where the actual load is super-estimated [and so the diversity].
For a steady state load- as in a Power Station- 100 % load factor one has to take a more elevated value.
And I agree with DRWeig, too .I doubt-at least for now- about cigar and donuts-but a good scotch it is a good reason to live!
RE: Neher McGrath Typical Value for Concrete
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: Neher McGrath Typical Value for Concrete
Reality is present RHO is no guarantee of future RHO, The real truth is nobody wants reality.