General Electric (1889-1920)

Thomson-Houston Recording Wattmeter
(DC & Single Phase)

(1889 to 1892)                                                                           
After Thomas Edison came up with his chemical meter in the late 1870s, he came up with the idea for a motor-type meter. However, since he preferred the chemical meter, he did not do any further work on it. In the mid-1880s, Elihu Thomson (likely with the help of Thomas Duncan) took this design, improved on it, and ended up with the first version of his 'recording wattmeter'. This meter was designed to work on both alternating and direct current and was much more rugged and accurate than other meters available at the time. The first picture shows an early prototype of the T.R.W., and the other two pictures are of an early production unit. The register on these early TRW meters is porcelain instead of the painted face found on the GE version.
Photo: Watertown Municipal Utilities collection

Thomson Recording Wattmeter (DC)

(1892 to 1910s)
Shortly after the merger of Edison General Electric and Thomson-Houston Electric, the T.R.W. was redesigned slightly and continued with a few changes along the way over the next few years. The T.R.W. was a commercial success, many of the early electric utilities quickly standardizing on this model. Initially, this meter was available in numerous styles covering the whole spectrum of applications from 3-amp models for smaller residential loads to models rated up to 1200 amps for heavy DC power circuits. There were also high-voltage versions made for metering the output of DC and AC arc-lamp generators. For AC applications, some were made for use with current and potential transformers to meter high-voltage / current circuits and (with appropriate resistance or reactance boxes) on balanced polyphase circuits. With the introduction and rapid acceptance of induction-type meters in the late 1890s (starting with Westinghouse's Shallenberger watthour meter and GE's Form C Induction Wattmeter), the T.R.W. was quickly relegated to use on DC circuits. In fact, the T.R.W. was the only commercially available DC meter for a few years until other manufacturers started making DC meters in the early 1900s. In 1904, the T.R.W. was superseded by the Type C Thomson DC watthour meters, but a few T.R.W.s were made into the 1910s.
Photo: Don Price collection

Form G (DC Switchboard)

The Form G was the first self-contained high-capacity DC switchboard meter. The current coil consisted of the two large cast terminals (which also served as the mounting terminals) and the 'U'-shaped yoke near the armature. Unlike GE's later DC switchboard meters, the brake disk and magnets were not shielded but located a distance from the current coil. The cover on this meter used glass on the front only and brass on the sides.
Photo Credit: GE Form G Meter Bulletin 

Thomson Recording Wattmeter (AC/DC Prepayment)

(1899 to 1903)
With the success of prepayment gas meters, GE decided to apply this concept to electric metering and introduced a special version of the TRW in 1899. This system consisted of two parts, a specially modified TRW (these have a register marked off to indicate the credit remaining per coin in addition to the normal watthour usage) and a prepayment device. At first, the Form 1 device (see center picture) was used, but this was replaced in 1901 by the Form 2 device (right). Both versions were built to take dimes and wound up a mainspring each time a dime was inserted. The dime interlocked the handle with the the mainspring gear and fell into the collection box at the bottom which had its own seal. The coin box could easily be exchanged with an empty one by the meter reader without emptying it. The meter had a contact device that completed a circuit at a preset interval and briefly energized the coil within the prepayment device, unwinding the spring notch by notch until a stop on the gear made contact with the switch, opening the circuit. In 1903, the TRW prepayment was superseded by two lines of prepayment meters: The IP series for use on AC circuits and CP series for use on DC circuits.
Photo: David Dahle collection 

Forms G-2 & GG-4; Type G-3 (DC Switchboard)

(1898 to the 1930s?)
After the Form G switchboard meter was introduced, an improved version known as the Form G-2 was introduced. The rectangular form fit better to the switchboard than the previous round case and the brake magnets and disk were now shielded against stray fields present on the switchboard. This model was built in both 2- and 3-wire versions and in a succession of models, each one being an improvement: Form G-2, Forms GG-2 through GG-4, and finally Types G through G-3. All these models were built in self-contained capacities from 2000 amps to a whopping 10,000 amps! 
Photo: GE TRW Handbook

Thomson Induction Wattmeter Form C (Single Phase)

This model was the first induction meter made by GE. This meter had separate magnetic structures for voltage and current coils and used an aluminum cylinder for the rotor (similar to the one found in Fort Wayne meters). A disk with permanent magnets was used for braking as in the T.R.W. meters. This meter was replaced the following year by the Form C-4.
Photo: GE Single Phase Metering Course Pamphlet 

Thomson Induction Wattmeter Form C-4 (Single Phase)

(1898 to 1902)
The Form C-4 was an improved version of the previous Form C, but was still quite primitive. The voltage circuit in this meter used an external reactance coil mounted behind the register (similar to the reactance coil as used in the early Ft. Wayne and Westinghouse meters). The coils and brake magnet were mounted on a platform underneath the disk (as opposed to the later practice of using a vertical frame). The only adjustment that is mentioned in the literature I have on this model was a light load adjustment that consisted of a copper shading strip between the poles of a starting coil. The cast metal cover of this meter (not shown) is very similar to the one used on the High Torque meter.
Photo: GE Thomson Induction Wattmeter Manual 

Thomson: Rectangular Pattern (Polyphase)

(1899 to 1905)
This meter (also known as the Form DF-2) was GE's first attempt at a induction-type polyphase meter. This meter was massive (twice as wide as the Thomson Recording Wattmeters) in order to space the two stators far enough that they would not interact with each other. This meter used construction very similar to the Form C-4 and High Torque meters, including the platform that supported the parts around the large disk's circumference. Because of the electric industry's desire for a more compact polyphase meter (and Westinghouse's successful introduction of the polyphase Round Type), this model disappeared into obscurity. 
Photo: Electrical Meterman's Handbook

Thomson: Round Pattern (Polyphase Switchboard)

(1899 to 1905)
This meter was GE's first attempt at a polyphase switchboard meter. This meter was massive (bigger than the Thomson Recording Wattmeters) in order to space the two stators far enough apart to minimize interference between the stators. This meter used construction very similar to the Form C-4 and High Torque meters, including the platform that supported the parts around the disk's circumference. The service version of this was known as the Form DF-2. Five- or six- dial watthour registers were used on these models. Two different covers were used, a metal one with a pane on glass in front and one with a circular piece of glass on the sides to permit visibility of all inner parts. 
Photo: GE Polyphase Recording Wattmeter Bulletin

High Torque (Single Phase)

(1902, 1903)
This model was the final version of the Thomson Induction Wattmeter, and it shares many similarities in design with the Form C-4 meter including the fixed brake magnets, reactance coil, and the starting coil. There was a second adjustment introduced on this meter - an anti-creep device which was a wire bonded to the disk near the hub that was bent towards or away from the shaft.
Photo: Electrical Meterman's Handbook 

Thomson C Series (DC)

(1904 to the 1930s?)
This meter used the same principles as the previous Thomson Recording Wattmeters but were made in a more compact and easier to handle enclosure. Like the preceding T.R.W. meters, the Type C meter came in several styles as well as a broad range of capacities from 5 to 10,000 amperes. Pictured below are two different styles of the C series DC meters. The one on the left is an early model that had the oval nameplate of the earlier Thomson Recording Wattmeters, and the second picture is the later version of the C series. The lower capacity versions were replaced in 1923 by the C-15 meter.
Photo: David Turner Collection

Type CS (DC Switchboard)

(1904 to the 1930s?)
With the introduction of the C series DC meters, the CS was included as the low- to medium-capacity (up to 1500 amps) switchboard model. This meter uses two oppositely wound armatures and field coils, and the disk and brake magnets are enclosed inside an iron case to protect the meter against effects from stray fields coming from the DC busses that fed the meter.
Photo: Yokogawa Electric Collection 

Type I (Single Phase)

(1903 to 1913)
The Type I was the first "modern" meter as it had all the basic features and adjustments found in today's meters. This model proved to be as popular with the utilities as the Thomson Recording Wattmeter had been just a few years earlier. In fact, this model proved to be dependable enough that many Type I meters were used into the 1960s (and possibly beyond). This is also the last model without a separate chamber for wire connections, the wires entering through holes in the sides of the base (requiring removal of the main cover for access to the terminals). The Type I comes in three different sizes depending on the meter's capacity. The vast majority of this model have metal covers, but a few have been made with glass covers (which have the nameplate attached to the cover instead of sitting behind the glass!). Most of the metal covers are stamped, but some of the very earliest Type Is have cast covers.
Photo: David Dahle collection 

Type IS (Single Phase Switchboard)

(1903 to 1905)
The Type IS' electromagnet was similar to the one in the Type I meter. The full-load adjustment was unique since the brake magnets were fixed in position, the full-load adjustment effected by adjusting moveable angle irons on the magnet ends as needed. The light-load adjustment was identical to the Type I, using a lever to move a metal punching near the voltage coil's flux path. A service version was made for a very short time (possibly only as a field trial) and was designated Type I-2.
Photo: GE Type IS Meter Booklet 

Type D-3 (Polyphase)

(1905, 1906)
This meter consisted of 2 Type IS single phase elements in one case, with a common register and shaft with 2 disks. As with the Type I, the wires were inserted into holes on the sides of the meter, and required removing the cover to get to the terminals.
Photo: Electrical Meterman's Handbook 

Types Ds-2 through DS-5 (Polyphase Switchboard)

(1906 to 1915)
With the introduction of the D-3 and D-4 polyphase meters, the DS-2 and DS-3 switchboard versions soon followed. In 1908, the DS-4 and DS-5 were introduced and these are identical to the DS-2 and DS-3 respectively except for the locations of the stators in the meter. The DS-2 and DS-4 both have cast metal covers (with windows for register and disk) and the DS-3 and DS-5 both have covers with glass windows on all sides.
Photo: Electrical Meterman's Handbook 

Type IP (AC Prepayment)

(1903 to 1906)
With the introduction of the Type I meter, the TRW prepayment gave way to a new model, the Type IP. The two parts of this system were retained, but the Type IP had a standard kilowatthour register instead of the specially-marked register of the prepayment TRW. As with the prepayment TRW, the IP had a contact device that tripped the coil in the prepayment device. The prepayment devices used with the IP were also redesigned. The Form 3 device (center) could be adapted to take either dimes or quarters, while the Form 4 device (right) accepted only quarters.
Photo: GE Prepayment Meter Pamphlet

Type CP (DC Prepayment)

(1904 to 1906)
The CP meter was simply a special version of the C-6 DC meter that had an extra terminal and a contact device for use with a Form 3 (or later, a Form 4) prepayment device. This allowed the meter to be installed at the service point and the prepayment device in a location more accessible to the customer.
Photo: GE Prepayment Meter Pamphlet 

Type I-8 (Single Phase)

(1906 to 1913)
In 1906, the Type I was redesigned by moving the terminals to a separately sealed chamber at the bottom of the meter to allow access to the terminals without having to take off the meter's cover. In all other respects, the I-8 was identical to the Type I, including the low capacity / high capacity sizes. This model also had an unique feature: the jewel screw was accessible from the outside of the meter once the terminal cover was taken off. 
Photo: Electrical Meterman's Handbook

Type IS-2, IS-3 (Single Phase Switchboard)

(1905 to 1915)
The IS-2 and IS-3 were back-connected versions of the Type I and were of identical construction internally. The IS-2 had a cast iron cover while the IS-3 had a cover with glass windows.
Photo: Electrical Meterman's Handbook 

Type D-4 & D-5 (Polyphase)

(1906 to 1915)
The D-3 was modified (along with the Type I) in 1906 to add terminal chambers that could be accessed without having to take off the meter cover. The D-5 was the 3-stator version of the D-4.
Photo: Electrical Meterman's Handbook 

Type IP-2 (AC Prepayment)

(1905, 1906)
The IP-2 meter combined the two halves of the IP into one unit - the Type I meter and the Form 3 prepayment device. As with the combined version of the Fort Wayne K prepayment meter, the prepayment device was operated by the meter register instead of a contact device and coil as in the Type IP.
Photo: GE Prepayment Meter Pamphlet 

Type CP-2 (DC Prepayment)

(1905, 1906)
The CP-2 meter combined the two halves of the CP into one unit - the Type C-6 meter and the Form 3 prepayment device. As with the combined version of the Fort Wayne K prepayment meter, the prepayment device was operated by the meter register instead of a contact device and coil as in the Type CP. Because of the meter's size, the coin box simply fastens to the cover instead of sitting under the meter like on other GE prepayment meters.
Photo: GE Prepayment Meter Pamphlet 

Type I-10 (Single Phase)

(1909 to 1913)
The I-10 was developed for metering low-capacity residential loads. This meter was of a completely unique design and none of this meter's features were incorporated into any later meter made by GE. The register on all I-10s had only 3 dials (except the 25-amp capacity model which had a more typical 4-dial register). The brake magnet was very similar to what was used in Duncan's M2 and MD meters, but the iron piece under the disk was fixed, the full-load adjustment being a screw that moved within the magnet's air gap. The light-load adjustment was the usual moving plate, but there were two clamp screws on the sides of the frame for manually positioning and locking the plate in position. This may be the only model known where the cover screws into the base like a jar lid. Most known I-10s have a metal cover as shown, but a couple examples are known with glass covers.
Photo: David Dahle collection 

Types IP-3 & IP-4 (AC Prepayment)

IP-3 (1906 to 1908), IP-4 (1908 to 1916)
The IP-3 was a redesign of the IP-2 using the Form 4 prepayment device instead of the Form 3 device. The IP-3 had the knob mounted on the prepayment mechanism, but any strain on the knob was prone to damage the mechanism, so it was soon superseded by the IP-4 which had the knob in the cover and had a notch on the back that operated a lever on the mechanism. The space above the register in both versions was for a scale showing the number of coins remaining to the user's credit.
Photo: Joe Maurath Jr. collection 

Types CP-3 & CP-4 (DC Prepayment)

CP-3 (1906 to 1908), CP-4 (1908 to the 1920s?)
The CP-3 was a redesign of the CP-2 using the Form 4 prepayment device instead of the Form 3 device. The CP-3 had the knob mounted on the prepayment mechanism, but any strain on the knob was prone to damage the mechanism, so it was soon superseded by the CP-4 which had the knob in the cover and had a notch on the back that operated a lever on the mechanism. The space above the register in both versions was for a scale showing the number of coins remaining to the user's credit.
Photo: Electrical Meterman's Handbook 

Type C-15 (DC)

(1923 to the 1930s?)
GE's push to redesign all their meters in the I-14's image eventually extended to the lower capacity DC meters, resulting in the C-15. This meter has a terminal block, register, and brake magnets like the later I-14s.
Photo: Dean Thatcher collection 

Types I-14 & I-15 (Single Phase)

I-14 (1913 to 1927), I-15 (1923 to 1927)
This model replaced the Types I, I-8, and I-10. The basic design of this meter (register and stator) introduced with this model carried over to all later models right up to the present (but not without improvements and changes along the way). This meter came in 3 different sizes, depending on the ampere rating (similar to the Duncan M2), and in all cases is a hollow iron casting with a rear cover accessible only when the front cover is removed. Unlike the I-8 and I-10 terminal covers, the I-14's terminal cover is captive (except on the 100A-300A versions) and swings out of the way when access is needed to the terminals. This meter was furnished with either a glass or a metal cover. In 1925 the magnet assembly was improved by adding a temperature compensator to keep the magnet strength constant over a wide range of temperatures, and these I-14s (and corresponding polyphase and switchboard versions) have the frame under the cover painted silver). The I-14 was also offered for use on 25Hz circuits, and this version was split off in 1923 and renumbered the I-15. The biggest difference between the I-14 and I-15 was that it had a full-load speed of 16 2/3 RPM to the I-14's 33 1/3 RPM.
Photo: David Dahle collection

Types IS-4 through IS-7 (Single Phase Switchboard)

(1915 to 1928)
With the introduction of the I-14, the IS-4 and IS-5 meters were introduced and were smaller than the IS-2 and IS-3, although they were similar in appearance. The IS-4 had a cast iron cover while the IS-5 had a cover with glass windows. When the 25Hz I-14 was reworked into the I-15, the 25Hz IS-4 and IS-5 meters became the IS-6 and IS-7, respectively.

Types D-6, D-7, D-9, D-8 & D-13 (Polyphase Switchboard)

D-6 (1915 to 1928, D-7 (1923 to 1928), D-9 (1925 to 1928), D-8 & D-13 (1925 to 1934?)
With the introduction of the I-14, the D-3 and D-4 gave way to a new family of polyphase meters. As with the I-14, the terminal covers of the D-6 are captive, sliding out of the way when access is needed. The D-7 is a slight improvement over the D-6 with its removable terminal covers. The D-9 is a 3-stator version of the D-6. As with the I-14, these polyphase meters were available with either metal or glass covers. Shortly after the 25Hz I-14 was split off to become the I-15, the 25Hz version of the D-6 became the D-8, and the 25Hz version of the D-9 became the D-13. Otherwise, these meters are identical to their 60Hz versions.
Photo: David Kingston collection

Types DS-6 through DS-13 (Polyphase Switchboard)

(1915 to 1928)
As part of GE's push to redesign all their meters based on the I-14, a new line of switchboard models was brought out. A brief table follows to correlate the switchboard types to their corresponding service type. When the 25Hz I-14 was renumbered the I-15, the corresponding switchboard models were affected. The DS-11 and DS-12 were split from the DS-6 and DS-7, and the DS-13 was split from the DS-9.
Photo by Charles Chiachiaro

Type IP-5 (AC Prepayment)

(1916 to 1920s)
The IP-5 was a complete redesign of the IP-4, using the I-14 as the basis for the meter. Instead of using the Form 4 prepayment device, GE reverted to using the Form 3 device which was probably a better fit to this design.
Photo: Handbook for Electrical Metermen 

Type I-16 (Single Phase)

(1927 to 1934)
In keeping with industry advances, GE revised the I-14 to add improvements that allowed accurate operation over a wide range of temperatures and loads. The cover was redesigned to attach to the base using a metal rim with bayonets, eliminating the wing nuts and studs formerly used to secure the cover. The terminal cover still had a corner pivot as on the I-14 but it could now be taken off if needed. In order to improve the meter's accuracy over a wider range of loads, the speed was reduced by half to 16 2/3 RPM. The earliest I-16s have a small nameplate very similar to the I-14's. There are three base sizes for the I-16, depending on capacity: one for 5 and 10 amp, a second one for the 15 through 50 amp ratings, and a special one for 100 amp 2-wire services. 
Photo: David Dahle collection

Type IS-8 through IS-12 (Single Phase Switchboard)

(1928 to 1980)
Following the introduction of the I-16 single phase and the DS-19 polyphase switchboard meters, a line of single phase switchboard meters was produced, and the table correlates the single phase switchboard models to their polyphase versions. In 1955, the chrome steel magnets were replaced with the smaller and more reliable Alnico V magnet assemblies.
Photo: Schenectady Museum Archives 

Types D-14, D-15 & I-18 (Polyphase)

(1928 to 1936)
Shortly after GE brought out the new I-16 single phase meter, 3 new polyphase models were introduced that had the same improvements that were incorporated in the I-16. As other companies were doing at this time, the terminals were moved from the sides to the bottom. The I-18 was a version of the D-14 developed for 3-wire network service and had a single phase terminal block. The D-15 was the 3-stator version of the D-14.
Photo by Marlow Galbraith 

Types DS-19 through DS-44 (Polyphase Switchboard)

(1928 to 1957)
With the introduction of the new D-14 and D-15 polyphase meters, GE brought out a new line of 2- and 3- stator switchboard meters. To keep all the styles straight, a table is included. These models originally had chrome steel magnets (as shown in the picture) but in 1955, a small Alnico V magnet was introduced (the same one as used on later V series polyphase meters).
Photo: GE Publication GET-1840 'Handbook for Watthour Meters' 

Types IS-20 & IS-A (Single Phase)

(1934 to 1937)
With the standardization of meters in 1934, the I-16 element was incorporated into the new meter housings, resulting in the I-20 series of meters, and it was made in 4 styles: I-20A, I-20B, I-20C and I-20S. The I-20A was the regular A-base meter. The I-20B had a special two-part terminal block that allowed easy testing of the meter in place. The I-20C was the I-20B with an enclosure for outside mounting. The I-20S was the socket version, and ones with S/N below 17,194,000 have the same full metal base as its competitors, ones beyond this S/N having the same large Bakelite insert as the I-30S. This unique base design allowed the I-20S to use the same meter element as the I-20A. The majority of the I-20 meters will have a small black nameplate similar to the I-16's but ones made in 1937 (and replacement units beyond this) have the same large silver plate as the I-30s.
Photo: David Dahle collection 

Types I-30 & I-30A (Single Phase)

(1937 to 1954)
The I-30 meter was similar to the previous I-20 but used a new stator that had increased overload capacity and improved compensation. There were two major changes that were made early in the I-30's production span. First, the chrome steel magnets (which had been used since the I-16) were replaced in 1938 with an Alnico I magnet assembly that was more resistant to loss of magnet strength from lightning or power surges. After WWII, the cast iron internal frame was replaced with one made from a lighter aluminum alloy. I-30A meters made during WWII have almost no aluminum in them (which was needed for the war effort) - they have steel alloy bases, iron internal frames, brass registers, and cardboard nameplates. The I-30S used a compression-molded insert in the base instead of individual bushings. Wartime units are similar to the pre-war and postwar units except for the cardboard nameplates. Although this meter was superseded in 1948 by the I-50, it continued in production until GE stopped making meters at its original plant in Lynn, MA in 1954 (moving all watthour meter production to a plant GE opened in Somersworth, NH in 1948).
Photo: David Dahle collection  

V Series (Polyphase)

(1936 to 1972)
In 1936, a completely new line of polyphase meters was introduced with the new standardized socket and A-base mountings. Unlike previous models that had several variations under the same model number, the V series had a separate model number for the type of service it was designed for: V-2 (3-wire network), V-3 (3-phase 3-wire), V-4 (3-phase 4-wire Y; 3 stator), V-5 (3-phase 4 wire Y; 2 1/2 stator), V-6 (3-phase 4-wire delta; 2 stator), V-7 (3-phase 4 wire; 3 stator), V-8 (2-phase 5-wire), and V-10 (totalizing). The V-4, V-7, and V-10 3-stator models were only made in A-base, all the others were available as either socket or A-base. Socket-type V-series meters use the same Bakelite-insert base as the I-30 single phase meter. Early V series meters had a chrome steel magnet which was replaced by an Alnico II magnet assembly in 1940 that was more resistant to surges. In 1955, a much more compact Alnico V magnet was introduced and was easier to adjust than the previous magnets.
Photo by Marlow Galbraith 

Types I-50S & I-50A (Singlephase)

(1948 to 1990)
The I-50 meter was a revolutionary advance in metering. Ever since the first meters were made, jewel bearings had been used which required periodic maintenance to keep the meter accurate. There had been a previous but unsuccessful attempt to use a magnetic bearing in meters in the late 1890s in the Stanley meters. GE had started research on an improved magnetic bearing in 1940, but this was interrupted by WWII. Development of this bearing quickly resumed following the war, and this magnetic bearing significantly reduced the maintenance required and allowed longer intervals between tests. Another major improvement was to incorporate the brake magnets and full-load adjustment into the frame, simplifying construction and adjustment of the meter. The self-contained version of this model was quickly replaced by the I-55 and I-60, but transformer-rated versions were made into the 1970s and special versions into the late 1980s. The I-50 family of meters is probably the only series of meters where the register and nameplate are one piece, but meters with S/N beyond #42,400,000 do have separate registers and nameplates.
Photo: Pete Mallet collection