Jan. 16, 1945.
R, A_ ROAD
>
2,367,433
PLASTIC WATT-HOUR METERBASE
Filed July 8, 1941
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54
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4 Sheets-Sheet 1
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’ ATTORNEYS.
Jan. 16, 1945.
R. A. ROAD
2,367,433
PLASTIC WATT~HOUR METER BASE
Filed‘ July 8, ' 1941
-
4 Sheets-Sheet 2
INVENTOR.
BY M7»
ATTORNEYS.
‘
Jan. 16, 1945.
R. A. ROAD
2,367,433
PLASTIC WATT-HOUR METER BASE
Filed July 8, 1941
l
I
4 Sheets-Sheet 5
l’atcntecl Jan. E6. 1945
STATES PATENT OFFICE
2,367,433
’
PLASTIC WATT-HOUR METER BASE
Richard A. Road, La Fayette, Ind, asslgnor to
Duncan Electric Manufacturing Company,
La Fayette, Ind, a corporation of Illinois
Application July 8, 1941, Serial No. 401,444
l3 @laims. (£31. 171—34l)
In bases for watt-hour meters there are a num
ber of features that are extremely desirable.
They should fit standard covers and connecting
‘facilities since interchangeability is important
commercially. The cover should seal tightly
against the base so that dust and water cannot
enter the meter chamber. Preferably, it should
be very difficult to drill a hole through the base,
Further objects and advantages of the inven
tion will be apparent, from the following descrip
tion and from the drawings, in which:
Fig. l is an exploded perspective view showing
the main porcelain body portion and separated
therefrom most of the parts which are applied to -
this body portion to complete the base.
Fig. 2 is a similar view showing the rear and
bottom of the body portion together with some
which a wire may be inserted or particles may 10 of the parts removed from the back thereof.
particularly into the meter chamber, through
be blown.
An electrical connection should be
provided for automatically grounding the meter
element to the connecting box (metal wire‘ hous~
ing) if a connecting box is provided. The base
should be highly weather-resistant since many of
the bases will be exposed to salty atmosphere near
the ocean. The various standard connections
must be possible and, in fact, the connecting fa
cilities should preferably be standard. Lightness
in weight is desirable to reduce shipping costs.
It is highly desirable that the terminals to which
the wires are connected be insulated from one
Fig. ‘l’ is a bottom view of the base.
is the most satisfactory which has been provided
it is especially satisfactory when a
heretofore.
Fig. 8 is a generally horizontal sectional view
taken approximately on the irregular line 8-8 of
Fig. 6.
Fig. 9 is a similar view taken approximately on
the irregular line 9-4? of Fig. 6.
Fig. 10 is a fragmentary vertical sectional view
taken approximately on the line l0—lll of Fig. 6.
Fig. 11 is a generally vertical sectional view
taken approximately on the line ll-ll of Fig. 1.
Figs. 12 and 13 are generally vertical'sectional
views taken approximately on the lines l2—l2
and lt-l 3, respectively, of Fig. 6.
Fig. 14 is a generally vertical sectional view
porcelain terminal‘ block, already available, is
taken approximately on the irregular line 14-14
another with
“non-tracking” insulating mate
rial. With some insulating materials, such as
.“Balrelite,” there is danger that under abnormal
circumstances a conductive path or track will be
formed on the surface of the insulating material,
and if this happensa current ?owing along the
track will increase. the conductivity of the track
and more and more current will pass until there ;
may even be an explosion.
,
A base similar to that illustrated in Holmes
Patent No. 2,046,307 has seen extensive use and
'
Fig. 3 is a fragmentary cross sectional view
taken approximately on the line 3—3 of Fig. 1.
Fig. 4 is a perspective view of the cover-secur
ing insert shown cemented to the base in Fig. 3.
Fig. 5 is a somewhat diagrammatic view illus
trating the manner of obtaining accurate posi~
tioning of the insert with respect to the body por
tion of the base as the insert is cemented thereto.
Fig. 6 is a fragmentary face view of the por
tion of the‘ base which forms the terminal block
showing wires connected thereto.
of Fig. 1, broken away to show the break-out wall
Ill.
cast aluminum. In~ view of the present abnormal
Fig. 15v is a fragmentary partly sectional view
demand for aluminum, it is desirable to provide
a base which is not made of aluminum but which 40 taken approximately on the irregular line l5-l 5
of Fig. 6.
_
has the above mentioned qualities nevertheless.
Fig. 16 is a fragmentary partly sectional view
According to the present invention, a porcelain
meter base with a terminal combined therewith _ taken approximately on the irregular line l6-l 6
of Fig. 1.
has been provided. This base has nearly all the
A preferred form of the invention has been
advantages of the Holmes aluminum base except 45
chosen for illustration and description, in com
that it- is a little heavier. It is not nearly as
used therein.
This Holmes base was made of
In
pliance with section 4888 of the Revised Statutes,
addition, it has other advantages, such as the
fact that it is largely made up of a non-trackable
insulating material which makes it safer than
previous meter bases and permits the integral
but persons skilled in the art will readily per
ceive other means for accomplishing the same
results, and the claims are therefore to be con
strued as broadly as possible, consistent with
incorporation of the terminal block therein.‘ It
the prior art.
heavy as a cast iron or steel base would be.
also is extremely hard to drill. A number of de
tailed problems had to be solved to provide this
base, but they have all been solved satisfactorily.
Although a major object of the invention was to
provide a satisfactorygbase not made of aluminum
or like metal, an additional'obiect was to solve
the various speci?c problems involved in the pro
vision of a porcelain base.
.
The body portion ll of this form of the in
vention is seen best in Fig. 1. This body portion
‘ is preferably porcelain molded in- one piece. A
dry process porcelain is preferred for reasons of
economy and because there is less shrinkage
than with the wet process. Any type of por
celain which- can be suitably molded and which
(ill will not deteriorate by exposure to weather even
2,367,438
under the most adverse conditions, such as al
ternate rain and freeze, may be used. A typical
formula would be: feldspar 36%, pctter’s ?int
passages 21 for receiving screws 23 and with
recesses‘ 28 for receiving screws 13 and Hi.
24%, Tennessee ball clay 20%, Georgia kaolin
slightly uneven wall without placing excessive
strain on the porcelain body portion, the hanger
10%, Florida kaolin 8%, and tale 2%. Com
position of such porcelain body may be varied
by substitut'ons and additions of such mate
rial as pyrophyllite, dolomite and, to produce
In order that the base may be mounted on a
I2 is arranged to project slightly rearwardly
from the body portion || so as to hold the body
portion slightly spaced from the wall.
It is
a gray body, not over 6% of iron chromate. The
likewise desirable that the lower end of the por
10 celain body portion be held slightly spaced from
materials are preferably air-?oated.
This body portion may be made of other plas
the wall, and for this reason the mounting means
tics, such as glass or the non-ceramic plastics
at the bottom of the body portion, namely the
of which “Bakelite” is an example. Glass is
plate 3|, is also arranged to project rearwardly
d'mcult, if not impossible, to mold in the com»
beyond the body portion. As a matter of fact,
plicated shape shown, however, and the ceramic ‘
it has been shown as being positioned entirely
plastics are preferred to the non-ceramic plas
behind a flush surface of the body portion, th s
tics now available because those which are con
being done because a ?at surface is preferred
sidered otherwise suitable are subject to “track
in order to facilitate supporting the entire body
ing"—the formation of a surface conductive
portion while it is being ?red. If a recess were
path thereon which progressively increases in
conductivity. It should be noted, however, that,
although porcelain is preierred, most of the de
provided for the plate 3| and the lower end not
supported, the lower end might sag and cause
tailed features of the invention would be as ap
should be of a thickness corresponding to the
plicable to other plastics, if they were chosen ‘for
use, as to procelain.
It is believed that the porcela°n body portion
excessive irregularities of shape. The plate 3|
projection of hanger l2 behind body portion ||,
25 preferably about 11; inch, so as to support the
body portion H in vertical position. The in
can best be described with relation to the vari-'
ous parts that are attached thereto.
teral parts will; of course, be dimensional to hold
the measuring element in proper position rela—
tive to the body portion ||.
Mounting features
30 The bottom mounting plate 3| is best seen in
It is desirable to provide the base with stand
Figs. 1, 10 and 15. This plate is secured against
ard mounting facilities. For this purpose it is
the back of the body portion II by means of two
desired to provide a keyhole hanger l2 on the
screws 32. As indicated in Fig. 1 and as seen
back of the meter near its top, this hanger be
in‘ Fig. 10, one of the screws 32 passes through
ing reversible to put either end up according to
the plate 3|, then through a hole 33 in the pro
the wishes of the particular power supply com
celain, and screws into a metal block 34, having
pany installing the meter.‘ To obtain this re
a second purpose described under the heading
versibility in the most desirable and standard
“Terminal chamber cover.” The 0‘: s; screw 32,
form it is necessary to secure the hanger l2 to
as indicated in Fig. 1 and as seen in Fig. 15,
the base of the meter by a screw l3 passing 40 passes through the plate 3|, then through another
through hole [4 in the hanger which must be at
hole 33 in the porcelain, through a sealing plate
the‘exact position shown best in Fig. 14. It so
36, and threads into a metal block 31. The
happens, however, that the standard meter
plate 3| is also provided with holes 39 through
measuring element for which this base is de
which mounting screws for the base may be
signed is secured to the base by three mounting
passed to screw into the wall against which the
lugs of which one is the upper lug I6, shown in .
base is mounted.
Fig. 14. Space requirements necessitate the po
The measuring element is provided with one
sitioning of this mounting lug It as shown in
mounting lug 4|, shown in dotted lines in Fig. 14,
Fig. 14,_and it will be noted that the hole |'|
on each side thereof. Each of these lugs is se
through this mounting lug is out of alinement
cured by a screw 42 which passes through the lug
with the hole I4 in the hanger l2.
and is threaded into a bushing 43. As seen best
It will be understood that the various screws
in Fig. 11, each bushing 43 is provided with an
cannot ‘be threaded into the porcelain since the
elongated portion 44 threaded at both ends, into
porcelain threads would chip off and would not
one of which a screw 46 is threaded to draw the
hold the screws reliably and are difficult and ex
pensive to form. Accordingly, metal portions
bushing 43 tight against the body portion II
or, more speci?cally, against a yielding sealing
must be provided for the screw l3 and the meas
uring element mounting screw I8 and, as pre
gasket 41.
viously noted, the two metal portions must in
this case have their tapped holes slightly out of
of a single tapped bore of portion 44, as shown
in Fig. 11. However, the construction shown in
Fig. 3 is preferred, the solid center portion of
the bushing positively preventing the seepage of
moisture along the threads. In Fig. 11, the head
alinement.
It will be observed that both the
screws 42 and 48 can screw into opposite ends
It is believed that in this instance the mis
alined tapped holes are best provided by the two
plates 2| and 22, seen best in Figs. 1, 14 and 16.
of screw 46 bears on grounding strap 48 which
These plates 2| and 22 are both drawn tight 65 is described under the heading “Grounding con
onto the body portion II by means of screws 23
nection.” As indicated in Figs. 1 and 3, the head
which are passed from the back of the basev
of screw 46 at the other side of the meter bears
through plate 22 and screwed into plate 2|. A
against a washer 49.
yielding sealing gasket 25 could be used under
Accurate positioning of parts
plate 22, the material known as “Velutex” being 70
at present preferred.
Since porcelain is not fired in the mold, there
‘The base II is provided with a suitable thick
are minute variations between successive body
ened portion 24 for properly positioning the plate
portions molded from the same mold, these varia
2| and a suitable recess 26 for receiving the plate
tions resulting from differences in shrinkage or
22 and the hanger l2. It is also provided with 75 the like. It is very desirable, however, that the
ea
asetgess
for mounting
measuring element be
accurately and uaiicrmly positioned with respect
one another.
This is preferably accomplished v
oi’ material as brittle
porcelain, there might
he excessive breakage. A’; the present time,
there-fore, a‘ non-ceramic plastic, such
tor the bushings
known commercially as “Llal
may he positioned with cw. ~ Eecause oi’ the fact th '.
.
able me
special precaution
1?“ “a
providing
these
oversiaed.
husliiags
holes
; substantially eli
I
’
from its use in this
through
to avoid.
al units below
connection
heretofore
" -* manufacture
the flange:
.
11a}: stra;
' T) having a bins»
6; the chances c
Acellte”) by de
.t with the
. ~ale there
-,
se.
is
ce
‘e edges
w. res
set outwardly
crtions o5
attao
:rrent coil of
"*l mayta
-
ter"
. lit, the rear edge
do
"more
he positioned in a
” .hcely portion ‘eel '
rece
‘.16
‘o hole
the nut
c'
"he
"
_,
-
the up
cal strap
is also provided with
~”
“
‘.4 .5
.
the screw to which may
he‘ screw, heals against a
. i'table by handle til to 1"!)
‘
ininal strap ‘U5 (Figs. 6 and 12) is fastened. A
spacer ‘it is provided on screw all so that the ass
sociatecl terminal unit will have a little play to
facilitate allnement of the terminal unit with
relatively in?exible connections, but such play
is not necessary tor
he parts associated. with
_
meter will ordinarily be provided with two
terminal units comprising the straps “ii and ter
minal member
it will also ordinarily be pro—
viclecl
although,
withasfour
seenofinthe
Fig.main
6, two
terminal
of themunits
will be
longer
room between
he
one‘:
or to be spaced
the
irecl. The screw
threads into
potential mom?
to which a potential ten
screw 68.
..
:1 plate ll}. If the “ ire is
’ at, it will usually be ‘bent forwardly,
and it y ll be ohsei
that there is much more
'
e
and the forward edge oi‘
orward edge is spaced
ivr'irclly of the normal position
we
under
link
' clown iroi
i
(.1.
also
‘l
" screw will screw
the other two.
The terminal units are inserted by removing
the screws therefrom, slipping them up into the
body portion, and inserting the screws through
appropriate holes in the front of the body portion.
rlf’l'lese screws, once screwed into the terminal
clamp hold the terminal clamp in place.
It is not desirable to have the bottoms of the‘
terminal units exposed, as this might result in
accidental shocks and might invite tampering.
According to the present invention, the terminal
units are shielded from the bottom by a guard
plate 173 formed of suitable insulating material.
Porcelain could be used. for this, but accurate
measurements are desirable and furthermore the
plate is relatively thin and long so that, if made
of the '
.. g screw
{is seen from
the side edges ‘ill of the wire-receiving
are spaced. anart more widely than the
inside op line‘ of terminal clamp
and each is
set heel:
the inside plane thereof. The
plate
I designed to have a slight clear~
ance (Tile. ill with the porcelain all around and
may be provided with lugs l5 ?tting beside spa»
oially provided lugs iii’ (Fig, 12) on the body
portion, hath of which are so disposed that the
guard plate can only be applied in one position
it right side up. ‘Lugs it’ can be omitted in the
interests ‘of simplification or
the guard plate
‘it is symmetrical so that its position is imma
terial. The lugs ‘l5 also decrease the likelihood
of tracking as do the grooves l9, by increasing‘
the surface distances between conductors, ac=
cording to principles taught in Patent 2,154,412
Gil issued, jointly to Stanley ‘S. Green and me.
In
the case of lug ‘E5 the surface distance increased
is that along the top of the plate "l3 between volt- '
age wires ill and brackets ‘it? which are the pre
ferred means for holding the guard plate ‘is in
place. The surface cteepage or tracking dis
tance along the bottom of guard plate ‘it’ from
wire ill to bracket ‘it is preferably increased,
not only by the downwardly extending skirt in
which holes Hll are formed, ‘out also by shaping
70 bracket ‘it with a cutaway shape at 80 in the
vicinity of wire Mi.
Brackets" ‘l6 are secured to mounting plate 3!
‘by lateral ?anges ll on brackets 16 welded to
washers ‘ll’ which are welded to the mounting
75 plate 3!. All of these parts may be spot welded
4
‘ 2,367,488
together simultaneously. These brackets 18 may
engage ?anges 18 formed integrally on the ends
of the guard plate 13. The brackets 18 are pref
body portion Ii with the inserts 83 therein safe.
erably somewhat curved or angular in cross sec
tion so as to increase their rigidity and so as to
ments.
istics. Of course, it must be waterproof. Lith
arge and glycerin cement or Portland cement are
also possibilities. A type metal may also be con
sidered as a suitable cement, since it has the de
Washers 11' are provided, and are ?attened on
their undersides, so as not to interrupt channel
sirable characteristic of expanding on cooling so
that it is sure to hold the insert 83 ?rmly.
88’ into which lip 8|’ of the connecting box may
The described method of mounting the inserts
83 in the base has the additional advantage that
it places the inserts properly with respect to
conform in shape to standardization require
extend as seen in Fig. 11.
It is desirable that
the connecting box be externally overlapped from
The cement 88 may be any suitable ceramic
cement, preferably of low shrinkage character
above wherever there is no other sealing, to
one another so that they de?ne a circle of pre
prevent water from running into the connecting
determined diameter appropriate for proper co
box.
15 operation with the cover. In other words, the
Meter cover
fact that the base may have shrunk will not
cause these lugs to be so improperly positioned
It is highly desirable that the meter base be
that there will be objectionable lateral play of
adapted to have standard covers mounted thereon
the cover.
,
.
so that these covers may be interchangeable be 20
The insert 83 may be made of any suitable
tween the new base and old bases. Heretofore
strong metal, the strongest and most n0n-cor~
these covers have been secured by three, bayonet
rosive consistent with price considerations being
clamps which, upon slightly turning the cover,
preferred. Among others, both the silicon bronze
slide under lugs formed on the base in the posi
known as “Everdur” and red brass are suitable.
tion of the lug 8| shown in Fig. 3. By turning
The insert 83 is preferably shaped so as to facili
the cover, the resilient bayonet arm of the clamp
tate the ?ow of the cement around it while, at
draws the cover tight against a sealing rib such
the same time presenting an irregular shape
as the rib 82 in Fig. 3. This arrangement is dis
which increases the safety with which it is an
closed in the Holmes Patent No. 2,046,307 men
chored. It may not only be irregular longitu
tioned heretofore. A porcelain lug in place of 30 dinally but it may be provided with the notches
the‘ lug 8| would not have adequate strength
89, seen best in Fig. 4.
for securing the cover. According to the present
Terminal chamber cover
invention, therefore, the lug 8| is formed as part
The region in which the terminal clamps 58
of a metal insert or slug 83 cemented in a recess
or passage 84 in the body portion I I. Since the . are located has heretofore been called the ter
covers require three of the lugs 8|, one of the
minal chamber, and for convenience this term
may still be used. Since a separate terminal
inserts 83 is thus cemented in each of the three
recesses 84 seen in Fig. 1.
block has been provided heretofore, the base has
in past been formed with this whole zone vacant
In order for the bayonet clamp to act properly,
it is necessary for the lugs 8| to be positioned 40 to leave room for the terminal block. Accord
accurately with respect to the sealing rib 82, a
ing to the present invention, however, it is un
derstood that the insulating portions of the ter
tolerance of only .005 inch in either direction
minal block are an integral part of the body
being permissible according to one manufac
portion. It is nevertheless necessary to provide
turer's standards. To provide this accuracy, the
sealing rib 82 is ?rst ground to a plane. It should 45 a metal cover 90 for the terminal chamber to pre
vent accidental shocks or tampering on the part
be noted, incidentally, that the provision of the
of unauthorized persons.‘ For the sake of inter
narrow sealing rib 82 not only aids in having a
changeability, it is again desirable that standard
high contact sealing pressure with the cover
terminal chamber covers ?t the new base. To
gasket but also greatly reduces the cost of grind
ing the sealing surface to ?atness, since the slight 80 this end the securing formations for the stand
ard terminal chamber cover 90 must be provided
amounts necessary to be ground from the narrow
in‘their usual positions. As seen in Figs. 1 and 10,
sealing rib 82 may be ground oif quite inex
the block 34 into which the screw 32 is screwed
pensively. The grinding of the sealing rib is
for securing the back plate 3| is provided with
considered necessary, ?rst because the ?nished
a button 8| at the proper position for engag
porcelain is not always uniform, and second be
ing s, keyhole slot in a conventional terminal
cause a ?ber gasket is preferred to a rubber
gasket since a rubber gasket might stick or more
or less vulcanize itself to the cover and to the
rib and prevent twisting the cover to loosen the
bayonet clamps.
After grinding the sealing rib 82 to a plane,
chamber cover 90. A hexagonal nut welded to a
plate having a rivet thereon may be preferable
from the manufacturing standpoint. At the
other end of the terminal chamber a link 82 is
slidably secured above the terminal chamber,
being secured as best seen in Fig. 15 by means
the three inserts 83 are secured to a jig repre
of a bracket 83 ‘which may be secured to the body
sented more or less diagrammatically by 88, and
portion by a rivet 94. The inner end 86 of the
the body portion H is slipped over them so that
each insert 83 extends into the recess 84, as seen“ 85 slidable link 82 is passed inwardly (to the left)
against a lug on the bottom of the cover 90
in Fig. 5. The insert 88 may be held to the jig
after the cover has been turned clockwise to
in any suitable manner, as by a movable spring
tighten the bayonet clamps. This method of
clip 81. It will be observed that the body por
locking the main cover is in accordance with
tion ll rests with its rib 82 on the jig while the
lug 8| also rests directly on the jig. Thus, these 70 standard practice, except that the method of se
_ two members are positioned with respect to each
curing the sliding link 92 is new. When the link
92. is in its inner locking position, the sealing
other with extreme accuracy. Any suitable
plate 88 (Figs. 1 andv 15)" extends through a
cement 88 is now poured into the recess 84, and
the parts are left on the jig until the cement has
slot 88 in the slidable link 92. The terminal
chamber cover 98 may now be closed‘With the lug
hardened sufficiently to make removal of the
accuses
on link $32 extending through a slot therein.
A conventional sealing wire may be passed
through an aperture in the lug ill with. its ends
secured in a lead slug to lock both the termi=
trial chamber cover ilil and link 532, the latter lock
ing the main. meter cover by engaging a lug
oi:
bottom. thereof to prevent turning the
to release the bayonet clamps. A. separate
='
ig wire may likewise he passed through an
other drilling recess Hill, the discor“
illil and its associated screws will b
Besides the facilities for the two
taken through'the recesses " ',
desirable to provide ccnnectio'os no"
devices in connection with de
this purpose, three additi "
i ii; are provided in the hotto
it, as. seen. in Fig.
Who
"e in the sealing plate
to separately lock 10 these recesses are’ drill out
sible a passage lit through
and through the main meter cover,
ing wires may extend into u. c
the front ends of these
This effectively p'tevents prying the
Hts downwardly
.
'
stud
cc
screw M92.
"attics
l to ti 1e
obtain access to a
"it might be noted that it
to provide porce
cg" the brackets
"
thin wall ill’ is preferably 12 o. LP
fracture, but it can easily be bro-hem. o‘
passage is to be used. it may b
insulating wall is re "ired hetwe
ter terminal units
betwe
sage
is provided ‘because
both connected i
.
voltage di erential
esirnal voltage
Goundiug
» is. to be formed
1.‘.
witi.
.éiccoi'ding to best wir
terminal blocl’; portion of the
.
on ii is provided w
a thin sealing
it is not necessary
grind this to a
tions and like metal poi. ..
iueut should be connect
it a meter tester shou'i
as by standing on a v
gas“
c (Fig. 11) may be used.
Possible 30
vulcanization of the rubber at this point does not
-t a serious danger since the terminal
c-.. m‘ber cover ild may easily be pried off even
nations and one of the c "is wrapped
if the "rubber should vulcanize.
Sometimes a dlfr‘ereut- means of securing the
this grounding of the
automatically whencve:
_ initial chamber cover is provided by a para
was used for housing “
_
ticular power supply organization, this means
meter.
comprising bolts screwed through the cover into
meter base. To accommodate these bolts,
meter unit was mounts “
This resulted 1"
metal lugs and the metal. frame was mounted
tapped holes Hill are provided. According to the
in contact with the connection be}:
present invention, these tapped holes
pro
be conventionally grounded. Although
vided at substantially no es ra cost by position»
obvious
of insulating
advantages
material
in ‘halting
accordance
the
a1 _
ing the screws
for the support plate Si so that
the tapped holes into which they screw are in
invention, this insulating materia
to
'
the correct positions to receive the COVGf-SGCllI-1 till care of the automatic grounding Oi.
meter
tug bolts. In other words, the screws
of
unit. According to the present invention, how“
course screw only about half way through the
ever, this failure is overcome with complete sat-v
blocks 36 and til or less? leaving the remainder
isfaction by providing the grounding strap (it.
oi the tapped holes loll for the cover-securing
seen best in Figs. 2 and ii. This grounding strap
bolts. ‘li‘hese bolts are of ‘course suitably sealed,
is connected to the laminations of
meter unit
as by a rod extending through the bolts and
by virtue of lying under the head of one of the
sealed this position.
screws is holding one of the bosses
bushings
flit in place. It should he understood that the
Additional connections
mounting lug ill on the meter unit is made of
metal and is in direct contact with the laminaw
For some circuits it is desirable tov have one
tions.
or tw extra voltage connections leading into
r)fhe grounding strap
is connected to ground
the meter, besides the connections provided
by being in contact with the mounting plate ill
through the four main terminal units to. For
which will automatically be placed in electrical
this purpose, drilling recesses Hill are provided
contact with the connecting box in mounting the
in the guard plate it, the position of these being
shown in Fig. 'l. The inner end of this recess
meter.
11 by the
Themember
connecting
i2l which
box is represented
may be a bracket
in
may be drilled out very easily to permit a wire
or
extension
on
the
back
of
a
connecting
box
iii to pass therethrough as shown in dotted
against which the meter base is clamped by the‘
lines in Figs. 6 and ‘12. The porcelain body por~
tion is provided with a passage M2 through 135 mounting screw Hit.
It should be observed that, as shown at H22:
which this wire may extend to the‘voltage con—
in Fig. 2 and in dotted lines in Fig. 11, the
hector till, being held therein by a screw lit
grounding strap 138 may be shaped with its lower
which may be inserted through the face of the
end curled up slightly, the curling being exag»
terminal block portion of the body member. A
like passage is provided at the other end of 70 gerated in the drawings. When the mounting
plate Si is tightened against the grounding strap
the terminal chamber portion of the body mem
it by screws 32 this curltwill be more or less
ber. Of course, when a feed wire IN is used,
straightened out and the grounding strap placed
the disconnect link 66 and its associated screws
under stresswhich presses the upturned end into
will be omitted. Likewise, when a'wire corre
sponding to wire I]! is extended through the 75 firm contact with the mounting plate 35. This
6
2,367,433
ensures a good grounding connection.
At the
present time welding of the ground strap to the
mounting plate 3| is preferred to the spring con
ta ct shown.
The grounding strap 48 should be made of some 6
weather-resistant material, such as galvanized .
iron. It may be noted, incidentally, that all of
the metal parts are preferably protected from
excessive corrosion either by composition or by
plating.
'
'
Antitampering features
The provision of the guardplate 13 and the
manner of securing it has already been described,
as has the fact that the securing brackets 16
therefor prevent access to the mounting screws
I02. The lip I21 and the blocking plate I29 have
also been described. The double wall of the
Holmes Patent No. 2,046,307 has not been pro
vided, but porcelain is so diflicult to drill that
this double wall is not believed to be necessary.
Furthermore, the use of a single wall which is
sufficiently difficult to drill so that a double wall
with Fig. 5. With the illustrated form it will
probably be desirable next to apply the mem
bers to which the meter element is mounted.
In
applying plate 2|, the plate 22 will of course be
applied. While applying one of the bushings 43,
the grounding strap 48 will be applied. Next, the
four nuts 62 will be inserted, after which the
four terminal units 56 will be slipped up into place
from the bottom of the body portion, and the
10 screws 59 inserted through the front to hold them
in place. At this time the voltage terminal units
69, ‘II will also be inserted from the bottom, and
whichever screws will be used therewith inserted
from the front. The guard plate ‘I3 may now be
5 applied, after which the mounting plate ill will be
put in place and drawn tight by screws 32. The
sliding link 92 may be applied by riveting the
bracket 93 to the body portion at any time.
In case the grounding strap is welded to mount
0 ing plate 3| the bushings '43' will probably be ap
plied last.
From the foregoing it is seen that a combined
meter base and terminal block is provided which
is completely non-conductive except where metal
for accessories thereto, and makes possible the 25 parts are desired, which is so completely immune
to corrosion or other changes upon exposure to
provision of a relatively smooth back wall which
even the most corrosive atmospheres that it does
is easily wiped clean. It may be noted in this
not need to be painted, and which is almost drill
connection that if a, portion of the meter wind
proof and tamper-proof' Furthermore, it con
ing is quite close to the base, there is no danger
of spark-overs because the base itself is formed 30 forms with existing bases in all respects in which
standardization is desirable, particularly as to the
of insulating material.
covers and meter units which fit it. It provides
To minimize the danger that someone will at
more space within the meter chamber than any
tempt to pry up the cover with a screw driver,
previous base which was as hard to drill into.
the outer wall of the meter base which comes
is not necessary provides more room within the
main meter chamber for the meter element or
almost into contact with the cover is beveled as
seen at I24 in Fig. 14. The cover should come
close enough _to the inner end of the bevel so that
there will not be room for a screw driver to be
Although it is not as light as an aluminum base.
it is considerably lighter than a cast iron base. In
spite of these advantages. it is economical in cost
and may even prove to be capable of manufacture
at a lower cost than any previous high quality
inserted between it and the cover, and the beveled
and terminal block assemblies.
portion itself will not provide a suitable purchase 40 base
I claim:
or fulcrum for prying with the screw driver.
1. A base for watt-hour meters and the like,
Formation of the body portion
comprising an insulating body portion formed of
a ceramic, having slots extending inwardly from
The body portion is of a shape which can be
molded in accordance with known molding prac 45 the outside thereof, terminal units positioned in
said slots and secured therein by binding screws,
tices, although it may be advantageous to point
said body portion having integral ceramic walls
out certain special features. No attempt has
insulating some of said terminal units one from
been made to illustrate a taper or draft for facil
itating removal of the molds or cores, but this 50 another, and a guard plate, of a plastic less brit
tle than the ceramic, outside of the terminal units
may be provided wherever desired.
and slightly spaced therefrom by an air gap to
Molding the slots for the terminal straps 51
may present a special problem since a core ap
proximately the shape of these straps might be
flexed under the molding pressures. To over
come this danger, these cores may be thickened
through most of their length, thus forming the
cavity I26, seen for example in Fig. 13. The lip
I21 at the upper end of this cavity should be left
so as to minimize the possibility of insertion of
prevent tracking between the terminal units along
the guard plate if the guard plate is trackable.
2. A base for watt-hour meters and the like,
,,r. comprising an insulating body portion formed of
a ?red ceramic, having a narrow sealing rib for
engaging a cover, having recesses adjacent the
sealing rib, and having irregularly shaped metal
lic inserts cemented in the recesses, each insert
having a lug extending therefrom in a direction
wires into the meter chamber by meter tamperers. 00 to engage a bayonet clamp to secure the cover to
Of course, if desired, the upper‘end of terminal
clamp 58 can also be obstructed by applying a
plate I29 thereto as the connecting unit 56 is in-\
sertedinto the body portion. Although this plate
has been shown as formed of insulation, it could
be formed of metal and, incidentally, could be
the base, the recesses being oversize with respect
to the inserts and the inserts being accurately po
sitioned with respect to each other and the seal
_,r. ing-‘rib independently of shrinkage or warping in
firing the base.
3. A base for watt-hour meters and the like.
comprising
an insulating body portion formed of
51 or terminal clamp 58.
'
a fired ceramic, having a narrow sealing rib ‘for
70 engaging a cover, having recesses adjacent the
Assembly
sealing rib, and having metallic inserts cemented
For the most part the assembly is apparent
in the recesses, each insert having a lug extending
from the foregoing description. Of course, the
therefrom in a direction to engage a bayonet
inserts 83 for securing the main cover will prob
clamp to secure the cover to the base, the recesses
ably be applied ?rst, as described in connection 75 being oversize with respect to the inserts and the
formed as an integral part of the terminal strap
>
Y 2,367,433
' inserts being accurately positioned with respect to
, each other and the sealingrib independently of
shrinkage ‘or warping in ?ring the base.
4. A base for watt-hour meters and the like,
comprising, an insulating body portion formed of
a plastic, having slots extending inwardly from
the outside thereof, and terminal units positioned
in and substantially-?lling said slots and secured
_- therein by binding screws and some of which are
7
portion for mounting the base to a wall, said
mounting plate securing said guard plate in posi
tion and being positioned to engage a conven
tional connecting box for wires leading to the
measuring unit, and said metallic means includ
ing said mounting plate being in contact with the »
metallic insert for grounding the measuring unit.
11. The method of making a base for watt
hour meters and the like, which consists in pro
positioned in closely spaced side by side relation 10 viding a preformed body portion of insulating
material, having a sealing surface lying approxi
ship but are insulated‘ from one another by a
mately in a plane and adapted for the sealing
wall of the plastic integral with the body portion.
5. A base for watt-hour meters and the like,
comprising an insulating body portion formed of
a‘ ceramic, having slots extending inwardly from
the outside thereof, and terminal units positioned
in said slots and secured therein by binding
_ screws, said body portion having integral ceramic
walls insulating some of said terminal units one
of a cover thereagainst, and having a plurality of
, pockets adjacent said surface but variably posi
tioned with respect thereto because of the form
ing process, temporarily securing three widely
spaced lugged metallic inserts in said pockets with
the lugs thereon adapted to engage bayonet cover
clamps and positioned accurately with respect to
from another and an integral front wall through -
said plane and in relation to one another but in
which the terminal-screws pass but which shield
said units from ‘the front.
dependently of their positions in said pockets,
and permanently securing said inserts to said
base while thus. temporarily secured by putting
cement in said pockets around said inserts.
- 6,. A base for watt-hour'meter's and the like,
comprising an insulating body portion formed of
a plastic, having passage means extending in
wardly from the outside thereof, terminal units
secured in said passage means positioned within
the ends of the passage means and surrounded by
the body except for their end faces, and an ‘in
sulating guard plate mounted outside of the ter-_
minal units.
7. A base for watt-hour meters and the like,
- 12. A base for watt-hour meters and the like
comprising- a ceramic body portion forming, in
part at least, a terminal chamber and a meter
chamber and having slots extending inwardly
through the terminal chamber and into the meter
chamber from the outside of the body, terminal
units positioned in said slots, secured therein by
'binding screws and having a terminal strap por
tion extending into the meter chamber through
a connecting portion of the slot, the connecting
wardly from the outside'thereof, terminal units 35 portion of the slot having such dimensions that
comprising an insulating body portion formed of
a plastic, having passage. means extending in
secured in said passage means, and an insulating
guard plate mounted outside of the terminal units,
, said insulating ‘guard plate having conductor-re
ceiving openings therethrough, the edges of which
are spaced slightly outwardly from alinement with
the conductor-engaging portions of the terminal
units whereby conductors passing through the
guard plate are unlikely to contact the guard .
plate.
8. A base for watt-hour meters and the like,
having terminal units positioned therein and ex
tending inwardly from an outer wall thereof, and
an insulating guard plate mounted outside-the
terminal units, said insulating guard plate having
conductor-receiving vopenings therethrough, the
edges of which are spaced away slightly from
alinement with the‘ conductor-engaging portions
of the terminal units,whereby conductors pass
ing through the guard plate are unlikely to con
_, its cross section is substantially ?lled by the ter
minal strap. said body portion having integral
ceramic walls insulating some of said terminal
units, one from another, and a guard plate formed
of a plastic less brittle than the ceramic but of
trackable characteristics secured outside of the
terminal units, substantially covering the ends
thereof exposed at the ends of the slots but
slightly spaced therefrom by an air gap to pre
vent tracking between the terminal units along
the guard plate, ‘said guard plates having/[holes '
through which conductors pass to the terminal
units, the walls of said holes being slightly spaced
away from the position which would contact a
straight conductor clamped in the terminal units
whereby the danger of tracking across the guard
plate between conductors is minimized. ‘
9. A base for watt-hour meters and the like,
13. A meter base for watt-hour meters and the
like comprising a ceramic body portion which has
been ?red, and means for mounting a meter mech
anism therein comprising three independent
comprising an insulating body portion formed of
I members each adapted to receive a mounting
tact the guard plate.‘
' '
,
a plastic, having a metal mounting plate secured
to the back portion of the body portion, a guard
member of insulation secured on the outside of
the base by said- mounting plate, and terminal
units within the base protected by said guard
screw for the mechanism, and each independently
secured in a hole by means passing through the
body of the base whereby a plane is de?ned, even
if there is warpage in the base for receiving the
measuring element with three-point mounting,
at least two of the holes being'oversize with re
spect to the means therein whereby the members
comprising a body portion formed of insulating 65 may be spaced accurately with respect to one an
other irrespective »of slight dimensional variations
material forming a measuring unit chamber and '
in the body portion, the front side of the body
a terminal portion, a metallic insert for mounting
portion being free from obstructions along cen
the measuring unit in themeasuring unit cham
tral areas thereof to provide the maximum depth
bergan insulating guard plate positioned outside
of the terminal-portion, and metallic means in 70 for receiving the measuring element.
RICHARD A. ROAD.
cluding a mounting plate secured to the body
vmember.
"
10. A base for watt-hour‘ meters and the lik