FreeLists / si-list / [SI-LIST] Re: Resistivity of Bras

[jrbarnes@xxxxxxxxxxx]

Rich,
Brass wire should be about 38 to 68 ohms-circular mil/foot..  The resistivity of
brass runs 61 to 110 nano-ohm-meters versus 17.2 nano-ohm-meters for copper.
50AWG bare copper wire, with a nominal cross-section of 1.0 circular mils, runs
10.66 ohms/foot.  As a cross check, 1AWG bare copper wire, with a nominal
cross-section of  83690 circular mils, runs 0.000129 ohms/foot which is
equivalent to 10.8 ohms/foot per circular mil.

If you need a closer answer, you will need to know the type of brass that you
are considering, because the alloying elements and their concentration affect
the resistivity of the alloy.  A Dogpile search (    http://www.dogpile.com/   )
found the following websites with information on the electrical resistivity of
various brasses:
*  http://www.matweb.com/search.htm   (search for "brass", choose an alloy and
its annealed/hardened condition--
    resistivity given in ohm-cm).
*  http://www.anchorbronze.com/alloydatabase.htm    (choose a brass alloy--
conductivity given in %IACS).

The resistivity values in the first paragraph are from Table 2 of my article:
[228a] Barnes, John R., "Designing Electronic Equipment for ESD Immunity,"
Printed Circuit Design, vol. 18 no. 7, July 2001, pp. 18-26. (download
from http://www.pcdmag.com/story/OEG20010928S0122)

The wire resistances are from a study on ampacity (current-carrying capacity) of
 wires that I did in 1999, based on
information from:
*  Basic Electronics and Radio Installation (Crane)
*  Carol Cable Company
*  Electrical/Electronic Interconnection Systems 4th ed (Lawrence)
*  Electrical Engineering Materials Reference Guide (Beaty)
*  Electronic Designers' Handbook (Giacoletto)
*  Electronic Engineers' Handbook (Fink)
*  Electronic Engineers Master
*  Electronic Failure Analysis Handbook (Martin)
*  Electronics Data Handbook (Barden)
*  Handbook of Wiring, Cabling, and Interconnecting for Electronics (Harper)
*  Helix/Hitemp Cables, Bare Wire Technical Data
*  Hitachi Electronic Wires and Cables
*  http://www.interlog.com/~speff/usefulinfo/fusing.htm
*  http://www.tridentalloys.com/impalloy/tablcond.htm
*  Design Guidelines for Electronic Packaging Utilizing High-Speed Techniques (
*  Madison Cable Corporation
*  Manhattan Electric Cable
*  Metro Wire & Cable
*  MWS Wire Industries
*  National Electrical Code 1990, Tables 310-16 through 310-19
*  National Wire and Cable Corporation Master Catalog
*  Phelps Dodge Magnet Wire Company, Engineering Data Copper Film Coated Magnet
*  Reference Data for Radio Engineers, 2nd ed (Federal Telephone and Radio Corp)
*  Royal Electric
*  Standard Handbook for Electrical Engineers, 9th ed (Knowlton)
*  The Design & Drafting of Printed Circuits (Lindsey)
*  The Handy HamBook (Wagman)
*  UL 1581 Reference Standard for Electrical Wires, Cables, and Flexible Cords
*  Wiring and Cable Designer's Handbook (Matisoff)

                                                   John Barnes  Advisory
Engineer
                                                   Lexmark International


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