> -----Original Message-----
> From: firstname.lastname@example.org [mailto:towertalk-
> email@example.com] On Behalf Of Jim Lux
> Sent: Monday, September 17, 2007 4:17 PM
> To: Gary Schafer
> Cc: 'TOWERTALK Reflector'; 'Jim Miller'
> Subject: Re: [TowerTalk] Ground wire
> Gary Schafer wrote:
> >> -----Original Message-----
> >> From: firstname.lastname@example.org [mailto:towertalk-
> >> email@example.com] On Behalf Of Jim Lux
> >> Sent: Monday, September 17, 2007 3:44 PM
> >> To: Jim Miller
> >> Cc: TOWERTALK Reflector
> >> Subject: Re: [TowerTalk] Ground wire
> >> Jim Miller wrote:
> >>> I usually do this, not asking it clearly. It makes perfect sense to
> >> but
> >>> I know what I am trying to find out.
> >>> I can run enough of the 3 wire #8 cords to be as large or larger than
> >>> whatever is recommended. What I should have specified is that the
> >> are
> >>> insulated (romax style) and then the separate runs of course are
> >> insulated
> >>> from each other and then bundled and ALL the wires at each end tied
> >> together
> >>> as if they were ONE conductor.
> >>> Now the question. I was wondering if the wires being insulated
> >> individually
> >>> will cause some adverse effect (being caused by their capacitance or
> >>> inductance to each other) on their capability to properly handle a
> >>> ("normal") lightning strike verses using a single conductor of similar
> >> size.
> >> The inductance will be LESS than a single conductor of the same cross
> >> sectional area. What you're basically implementing is a version of the
> >> "bundled" conductors you see on HV transmission lines, or, for that
> >> matter a form of Litz wire.
> > Jim,
> > Won't the inductance be greater because of mutual inductance between the
> > parallel wires?
> Think of it this way. Say you had 2 wires side by side.. it has some
> mutual L. Separate the wires by some distance.. the mutual L is less,
> so the overall L is less.
I guess you are describing 2 conductors of the same original size so that
the overall cross sectional area is doubled. I agree that the inductance
would be less in that case, however not half.
I thought Jim Miller had asked about using 2 or more wires of smaller size
to EQUAL the cross section area of a single large wire.
That is why I was saying that the overall inductance would be greater than a
single wire, because of the mutual inductance between the wires when in a
bundle. Yes, separate them and the mutual inductance is reduced and the
overall inductance is reduced.
Two wires of the same size does not reduce the total inductance to 1/2 of
what a single wire is because of the mutual inductance between them. If they
are sufficiently separated then it will be 1/2.
> The solid conductor is sort of the limiting case where the wires are
> You also pick up some benefit from the fact that the "surface area" is
> larger in the multi strand case, so the impact of skin effect is less.
> Terman has a description of this, and the equations..
As I understand it multiple insulated wires are more effective at some low
frequencies but at most of the lightning spectrum it doesn't really help.
> > Also Litz wire must be specially woven to be effective and then its
> > are only good at low frequencies.
> Actually, it doesn't have to be woven. It can be parallel strands on a
> non-conductive/non-magnetic core. Woven or braided is just more
> convenient, because, usually, you're interested in the lowest inductance
> for a given overall diameter, and the braid pattern does just that. A
> better statement would be that special winding/braiding techniques are
> needed to optimize the performance of Litz wire, but one can make your
> own Litz wire by just bundling enameled magnet wire. It will be lower L
> and lower AC resistance than the same amount of copper as stranded or
> solid wire, but not as good as the real thing.
> The benefits vs frequency vary depending on the number of strands, the
> packing density, etc. At some point, it doesn't buy you anything over a
> solid tube.
> I used to use what was essentially coax braid over a fiber core as a low
> inductance HV Pulse conductor.
> > 73
> > Gary K4FMX
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