Willmar tribune. [volume] (Willmar, Minn.) 1895-1931, 1914-07-15

earth, are already partly provided
with lightning protection. If rods
are added to such buildings the rods
should be put in direct metallic con-
nection with the roof and other metal
work about the building wherever
practicable. All down spouts should
be led into metal pipes going into the
earth to give the proper earth con-
nection, or the spouts should other
wise be we'll grounded by use of wires
or cables. Insulators are entirely un-
necessary and it is proper to have ex-
tended metal work in buildings, like
heating and water pipes, all electric
ally connected together and all we'll
grounded. This latter result is gain
ed incidentally through connections
made to water pipes, since the latter
usually pass through the earth out
side the building.
a. Are gilded or otherwise expen-
sive points of platinum or special
metal or of fanciful construction
necessary? Answer: No; not in the
least. Sharp needlelike points are eff
fective in dissipating small sustained
electrical charges, but such electrical
manifestations are perfectly harmless.
The imagined superiority of such
fanciful points is utterly valueless
when the rod is struck by a real light
ming flash. The useful qualities light
ming rod points must possess are in
fusibility, mechanical strength and
security of installation, and perman-
ence and durability under prolonged
exposure to the weather. Stout blunt
ly-pointed iron rods three-eighths or
one-half inch in diameter rigidly and
securely fastened so as to project 1h
or feet above the structure to which
they are attached satisfy all the re-
quirements.
(5) What material is best for con-
ductors or rods? This question can
not be answered fairly in a single
statement.
Because of it's availability and
| cheapness, as we'll as it's electrical
properties, iron is one of the best ma
terials for rods. Iron, however, rusts
and deteriorates under prolonged ex-
posture to the weather. This is only
partly overcome by galvanizing;
hence galvanized-iron lightning rods
should be of ample size (not less than
one-quarter inch in diameter) care
fully installed and subjected to sys-
tematic inspection and repair.
| Two-strand cable galvanized-iron
fence wire of substantial size of the
same style as barbed wire but with.
out the barbs furnishes very good
material for cheap iron lightning
rods. The presence of the barbs con-
stitutes a rather serious inconven-
fence in handling and installing such
conductor, and no material benefit
is derived from their presence.
Copper is better than iron not only
on account Of its indestructibility but
also because of it's softness and plia-
bllity which make it easy to install.
Scientists are not in accord in regard
to the relative merits of the electrical
properties Of copper and iron, but in
any case questions of cost, durability,
and the like far outweigh minor diff
ferences In electrical properties.
aluminium is competitor for iron
and copper for lightning rods. It's
durability under exposure to weather
is in it's favor, but its fusibility makes
it inferior to iron for points.
| If low first cost is the controlling
factor, galvanized-iron rods must be
chosen, but subsequent inspections
must be made and repairs may be-
come necessary.
If higher first cost is not an OBJ
stacle, the choice should go to copper
first or possibly aluminium,
(6) Should lightning conductors be
made in the form of solid rods, fiat
bars or bands, stranded twisted ca.
bles, woven stranded ribbons, or hol.
low twisted cables? Answer: Any OF
the forms may properly be employed
or two or more forms may be employ
ed In combination. Conductors should
be put up in long continuous pieces
as far as possible Solid round wires
one-quarter to one-half inch in diam
eter are best for this purpose. Con
ductors of size larger than one
fourth inch, however, present diff
culties in handling and installation II
the rods are solid. It then becomes
better to use stranded cables and
other similar forms. Long continu
GUS lengths, ample cross section com
bined with flexibility and the ease Of
it's installation over crooked courses
render stranded cables, in general
better than any other form Of con
ductor available. .=5 = s ss. .:sS :
Substantial iron points in combina