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Updated March 11, 2008

Insulator Manufacturing Companies and Related Companies - Master List

This list includes insulator manufacturers, electrical supply houses, holding companies, precursor companies, utility companies, telegraph companies, telephone companies, major buyers such as railroads plus some other related companies.



A.B. Chance Co.
A.J. Wilkinson& Co.
Accumet Engineering Corp.
Adamant Porcelain Co.
Aeolus Corp.
Aetna Glass Works
AGEE (Australian Glass insulator maker)
AGM (Australian Glass insulator maker)
Ajax Electric Specialty Co.
Akron High-Potential Porcelain Company
Akron Insulator & Marble Co.
Akron Marble Co.
Akron Porcelain Co.
Akron Porcelain and Plastics Co.
Akron Smoking Pipe Co.
Aktiengesellschaft Brown Boverie & Cie
Alberts & Kluft (Holland)
Algoma Eastern Railway (AER) (Canadian Railroad)
Allied Insulators Industrial Products Ltd.
Allied Porcelain
AlSiMag Technical Ceramics Inc.
American Automatic Electric Sales Co.
American Electric Co.
American Hard Rubber Co.
American Insulator Co.
American Iron Glass Pipe and Plate Co.
American Jobbers Supply Co.
American Lava (AlSiMag) (Chattanooga, TN)
American Porcelain Co.
American Porcelain Works
American Telephone and Telegraph Co.
Amy, Aceves & King
Anchor Electric
Anciens Etablissements Parvillee Freres & Cie (France)
Anderson, J.M. & Albert Mfg. Co.
Anderson Porcelain Co.
Andrae, Julius & Sons Co.
Ankara Seramik Porselen A.S. (Turkey)
Arabia Porcelain Company (Finland)
Architectural Tiling Co., Inc.
Aristic Porcelain Co.
Armstrong Cork Company
Arsenal Glass Works (Precursor to Beaver Falls Class Co.)
Associated Ceramics
Australian Consolidated Industries
Australian Glass Manufacturers 
Australian Porcelain Co.
Australian Porcelain Insulators Pty.
Austin Insulators Inc .
Automatic Electric Co.
AXA (Mexico)
B.F. Goodrich
Babson Brothers (U.S. electric fence supplier)
Baltimore Glass Manufacturing Company (U.S. glass insulator maker)
Barberton Pottery Co.
Barkelew Electric Mfg. Co.
Barker & Williamson Co.
Barns & Kobert Manufacturing Co., Milldale, CT (Pole line hardware)
Barron, James S. & Co., New York
Bassett, G. M. Glass Co.
Baudour (Belgium)
Bay Ridge Specialty Shop
Bay State Glass Works
Baily Electric Supply Co.
Beaver Falls Glass Company (U.S. glass insulator maker)
Belden Mfg. Co.
Belknap Hardware & Mfg. Co.
Bell Pottery Co.
Belling & Lee, Ltd (U.K.)
Bennett, A.R.
Bennington Potteries
Bentley-Knight Electric Company
Bergman Electric Co.
Bernard Co.
Bing & Grondahl (Denmark)
Birnbach Radio Co., Inc.
Boch Porcelain
Boston & Sandwich Glass Company
Boston Bottle Works
Brach, L.S. Mfg. Co. (Radio strain insulators and lightning arrestors)
Brady Electric & Mfg. Co., New Britain, CT
Brewer-Titchner Corp. (Insulator Hardware Maker)
Brilliant Glass Co.
British American Glass Works
British Insulated Callender's Construction Company Limited
British Insulators and Helsby Cables
Britten's Patent Glass Co. (Northamptonshire, England company)
Brookfield Glass Co.
Brooklyn Flint Glass Company
Brooklyn Wireless and Electrical Novelty Co., Brooklyn, NY
Brown Boveri & Co. (BBC)
Brown and Thompson
Brunt Porcelain Co.
Brunt Tile and Porcelain Co.
Brush Electric Company
Bryant Electric Co.
Bud Radio Inc.
Budwig Mfg.
Buell, M.A.
Buffalo Electric Co., Inc
Bullers Ltd. (England)
Buller, Jobson & Co. Ld. (England)
Bunnell, J.H.
Burgess & Co., Liverpool, Ohio.
Burlington Glass Works
Burndy Engineering Co., Inc.
Bushing Co., Ltd. (Hebburn-On-Tyne, England)
Bushwick Glass Works
Buzby, J.F.
C.E.L. Co.
C.F.I. Corp.
C.S. Knowles Co.
California Electrical Works
California Glass Insulator Company
Canada Glass Co.
Canada Glass Works
Canadian General Electric Co. Limited.
Canadian Line Material Co.
Canadian Ohio Brass Co.
Canadian Porcelain Co.
Cannington Bennett & Co. (Manchester England)
Carborundium Co., Latrobe, PA.
Carey Ohio Porcelain Co.
Carpenter Technology Corporation

Cartel Vidreria Monterrey (Mexico)
CCX, Inc. (Shortened name of Continental Copper and Steel Industries, Inc., parent of Continental Rubber Works)
Celeco. (Mexico).
Centerflex Technologies Corp.
Central District & Printing Telegraph Co.
Central Electric Co.
Central Porcelain Works
Centro Vidreiro Do Norte Du Portugal, Lda. (Portugal)
Ceramic Allied Products, Inc.
Ceramic Electrical Co.
Champion Sparkplug Co.
Chance Co., A.B.
Charbonneaux & Cie (France)
Charleston Electrical Supply Company
Chicago Insulator Co.
Chomel-Legrand (France)
Christalerias Rigolleau S.A. (Argentina company that made glass telephone insulators)
Cincinnati Glass Works
Cincinnati Flint Glass Works, John Jukes'
Cincinnati Porcelain Co.
Circle F Manufacturing Co.
City Fire Alarm
Clarksburg Glass Co.
Closter Vielsdorm (Germany)
Cochrane Dunlop Hardware Limited
CODARVI (Uruguay)
Cohansey Glass Mfg. Co.
Collins Overland Telegraph Company
Colonial Electric Co.
Colonial Insulator Co., Akron, OH
Colonial Porcelain
Colonial Sign & Insulator Co.
Colorado Glass Works
Columbian Electrical Supply Co.
Consumers Insulator Co.
Consumers Porcelain
Continental Rubber Works - Eire, PA maker of rubber insulators
Continental Copper and Steel Industries, Inc. (Parent Company of Continental Rubber Works)
Cook-Ceramic Co.
Cook Electric Co.
Cook Porcelain Insulator Co.
Cook Pottery Co., Trenton, NJ
Cooke Wilson E.S. Co.
Cooper Power Systems
Cooperativa de Aristas de Vidrio
Cooperativa Integral de Vidriera de Columbia
Co-Operative Flint Glass Company
Corning Glass Co.
Corning Glass Works
Cornish Wire Co.
Corwico (Cornish Wire Co.)
Cotronix Corp
Craighead Engineering
Cristaleria, S.A. (Mexico)
Cristalerias de Chile (Chile glass insulator maker)
Cristalerias Rigolleau, S.A. (Argentina)
Cristales Mexicanos, S.A. (Mexico)
Crouse-Hinds Company
Crowley & Co., Inc.
Crown Crystal Glass Company Ltd. (Australian glass insulator maker)
Crystal Glass Company, Ltd. (Canada)
Crystallite Products Corporation (Maydwell insulators)
Cullinan Industrial Porcelain Ltd. (South Africa)
Curran-Pfeiff Corp.
Curran-McQuilken Co.
Cutter, George Co.
Cutter, Scott C.
Daburn Electronics and Cable Company
Dalian Insulator Works (China)
Davidson Porcelain
Davidson & Stevenson Porcelain Co.
Dayton Aircraft Products
Decca Records
De Fuisseaux, L. & F. Fabricants Baudour (Belgium)
DeJur Lightning Arresters
Delta-Star Electric Co.
Denver Art and Plate Glass Company
Denver Flint Glass Company
Dexmar Minnesota Inc.
Diamond Flint Glass Companies (Ltd.)
Diamond Glass Company
Diamond Porcelain Co.
Dixie Electrical Mfg. Co.
Dominion Glass Company
Dominion Insulator & Mfg. Co.
Dominion Telegraph Company
Douglass, Rutherford & Company
Doulton & Co., Ltd. (England)
Doulton Insulators Australia Pty. Ltd.
Drew Electric & Mfg. Co., Cleveland, OH
D.T. Co
Duck, J.J. Co.
Du-Co Ceramics Co.
Dulms (Australia)
Duquesne Glass Company
Duquesne Glass Works
Duquesne Mine Supply Company
DX Instrument Co.
E.F. Johnson Co.
E.S. Greeley & Company
ESSCO (Electric Service Supplies Co.)
Eagle Electric Mfg. Co.
Eagle Porcelain Co.
East End Pottery Co.
East Liverpool Elecrical Porcelain Co.
Edison Electric Light Co.
Edison General Electric Co.
Edison Lamp Co.
Edison Machine Co.
Edison Storage Battery Co.
Edmonton Dunvegan and British Columbia Railroad
Edward Hines Lumber Co.
Edwin Lewis Co.
Efficiency Electric Co.
El-Fauly Co. (Egyptian Ceramic Factory)
Elan Technology
Electric Appliance Co.
Electric Corporation.
Electric Good Mfg. Co.
Electric Ordinance Accessories Co., Ltd. (England)
Electric Porcelain & Mfg. Co., Trenton, NJ
Electric Porcelain Co.
Electric Porcelain Works
Electric Railway Equipment Co.
Electric Service Supplies Co. (Franklin Porcelain)
Electric Storage Battery Co.
Electric Transmission, Ltd. (England)
Electrical Construction & Maintenance Co.
Electrical Engineers Equipment Co
Electrical Glass Corp.
Electical Insulator Mfg. Co.
Electrical Mfg. Co.
Electrical Porcelain & Mfg. Co.
Electrical Supply Co.
Electrovidro, S.A. (Brazil)
Electrose Manufacturing Co.
Elektroporcelain Arandelovac (Yugoslavia)
Elk Engineering Co. (Sales Representatives for Quanah Co.)
Ellenville Glass Works
Elmer Glass Works
Empire China Works
Empire Porcelain
Erie Electrical Equipment Co.
Erie & Michigan Telegraph Co.
Erie Railway Co.
Erner Electric Company
Erner & Hopkins Co
Esperanza, S.A. (Spain)
Essantee Switchgear Limited
Etho Carbon Crete Insulator Company
Ette Investment Co.
Evarts-Hull Co., Madison, CT - Pin Maker
Everready Porcelain Co.
Excelsior Glass Co.
F.A.P.A. (Argentina Railroad)
F.C.M. (Fernando C. Mesa)
Fahnestock Electric Company, Inc
Fairey Insulator Div., Fairey Engineering Group (Allied Insulators, Doulton Insulators, Hopyard
Fairmount Elec. & Mfg. Co.
Fall River Police Signal
Fansteel Products Co.,Inc.
Federal Porcelain Company
Federal Sign & Signal
Fernando C. Mesa
Ferro Corporation - Diamonite Plant
Fidenza Isolatori (Italy)
Fidenza S.A.
Fidenza Vetraria S.A.
FIL (Italy)
Findlay Electrical Porcelain Co. 
Fleron, M.M. & Sons
Fletcher, J.R. Mfg. Co., Dayton, OH
Florenz (Australia)
Florida Wire and Cable, Inc.
Fobes, S. & Co.  (U.S. Electrical Distributor, possibly of S.F. insulators but also of Hemingrays)
Folembray (France)
Fort Wayne Electric Works
Foster Brothers Glass Co. (Canada)
Fowler Brothers (Australia)
Frank C. Teal Co.
Frank H. Stewart Electric Co.
Frank Ridlon Co.
Franklin Porcelain Co.
Franklin Telegraph Co.
Freeman Porcelain Co.
Fred M. Locke
Fry, H.C. Glass Co.
Fry & Scott Co.
Fry, Sample & Reynolds Co.
Fuller & Sons (Bow, England)
G.B.C. Materials Corp.
G-Line Communications
G.M. Bassett Glass Co.
G.T.E. Corp.
G.W. Kearns Co.
G & W Electric Specialty Co.
Gaskell and Grocett (England)
Gatchell, Moore & Co.
Gayner Glass Works
Gem Clay Products
General Bakelite Company
General Bronz
General Cable
General Ceramics & Steatite Corp.
General Ceramics Corp.
General Electric Co.
General Porcelain Co.
General Power Company Pvt. Ltd. (New Delhi, India)
General Radio Co.
George Rutherford & Co.
Gijon Fabril, S.A. (Spain)
Gilchrist Jar Co.
Gillinder & Sons Glassworks
Ginori, Richard (Italy)
Gladding Ceramic Insulator Co.
Glasco Electric Company
Glass and Closure Division of Armstrong
Glass Container Association
Glass Insulators, Ltd. (South Africa)
Globe Porcelain Co.
Good, Robert Jr.
Goodrich, B.F.
Gould, Inc.
Gould Storage Battery Co.
Grand Trunk Pacific
Grand Trunk Pacific Telegraph Co.
Grand Trunk Railway
Granite Glass Works
Gray & Hemingray
Gray & Hemingray Glassware
Gray, Hemingray & Brother
Gray, Hemingray & Brothers
Graybar Electric
Great Northwestern Telegraph Co.
Greeley, E.S. Co.
Greenwood Pottery Co.
Gregory, F.W.
Grey, Lawrence
Gustin-Bacon Manufacturing Co.
Hall China Co.
H.C. Fry Glass Co.
H.K. Porter Co.
Hamilton Glass Company (Canada)
Hamilton Porcelains, Ltd. (Canada)
Hamilton Glass Works 
Hamilton Porcelain
Hammond Cleat & Insulator Co.
Hard Manufacturing Co. (Maker of what may be a glass battery rest)
Harloe Insulator Co.
Hartford Faience Co.
Hall Signal Company
Haviland, Johann (Bavaria Germany)
Hazel Atlas Glass Co.
Heinemann Electric Co.
Heinrich & Co. (Selb Bavaria Germany)
Hemingray Glass Co., Inc.
Henan Beauty Hair Products Co., Ltd. (China)
Hendricks Wire & Cable
Henley, W.T. Telegraph Works Co. Ltd. (England)
Henry L. Walker Co.
Hercules (see Hull, S.W. & Co.)
Hermsdorf-Schomburg-Isolatoren G.M.B.H. (Germany)
Hi-Line Utility Supply Co.
High Tension Electrical Supply Co., Abington, MA
Hindustan Chemicals (India)
Hipple, S.R. (see Fil-Ko)
Hoechst Ceramic N. America Inc.
Holcomb, J.R., & Co.
Hough, Rees & Co.
Hoyand Electrical Industry Co., Ltd. (Taiwan)
Hubbard & Co.
Hudson Bay Railway
Hughes Brothers
Hughes Peters Electric Corporation
Hull, S.W. & Co.
Hunsruck Porzellanfabrick (Germany)
Hunan Zhongnan A & T Co., Ltd. (China)
Ideal Insulator & Mfg. Co.
Iden Industries Inc.
IFÖ (Sweden)
Iittala Lasitehdas (Finland)
Illinois Edison Porcelain
Illinois Electric Material Co.
Illinois Electric Porcelain
Illinois Glass Co.
Illinois McGraw Electric Co.
Illinois Pacific Glass Co.
IMEC (Italy)
Imperial Porcelain Works
Improved Gilchrist jar Co.
Indepor Inc.
Indiana Glass Co.
Industria Milanese Elettro Ceramica (Italy)
Industrial Ceramics, Inc.
Insulaline Corp. of America
Inter-Mountain Electric Co., Salt Lake City, UT
Iran Insulator Co.
Iron City Electric Co.
Iron Glass Co.
Iron Glass Works
Isolantite, Inc.
ISOREX (France)
I-T-E Imperial Corp.
J.E. Saunders & Co.
J.F.D. Mfg. Co.
J.H. Bunnell & Co.
J.J. Duck Co.
J. Stolle Niemen
Jacobs, Charles F.
James B. Lyon & Co.
James Macintyre & Co., Ld. (England)
Jarsan Electric Co., Ltd (Taiwan)
Jefferson Plate Glass Co.
Jeffery-Dewitt Insulator Co.
Jenkins, D.C. Glass Co.
Jenaer Glaswerk Schott & Gen. (Germany)
Jerome Redding & Co.
Jewell Electrical Instrument Co.
Jobson Bros. (England)
Johann Haviland (Bavaria Germany)
John Jukes Cincinnati Flint Glass Works
Johns, H.W. Mfg. Co.
Johns-Manville, H.W. Co.
Johns-Pratt Co.
Johnson & Watson
Johnson, E.F. Co.
Joslyn Manufacturing & Supply Co.
Jukes, John Cincinnati Flint Glass Works
Julius Andrea & Sons Co.
Kadco Ceramics
Kalamazoo Valley Electric Co.
Kantstrike (see Quam-Nichols Co.)
Kanyo (Japan)
Karhulan Lasitehdas (Finland)
Karlsbader Kaolin-Industrie-Gesellschaft (Austria-Hungary)
Kearney, James R. Corp.
Kearns, G.W. Co.
Kellogg Switchboard & Supply Co.
Kennilworth Tile
Kentucky Glass Works
Kenosha Insulator Co.
Keramische Sondermassen (Germany)
Kerr Glass Manufacturing Corp.
Keystone (see ESSCO)
Kilner Brothers
Kimble Glass Company
King City Glass Works
Kirchberger & Co.
Kirkman Engineering Corp. (New York)
Kleinig & Blasberg
Klingel, E.L.
Knowles, C.S. Co.
Knox Porcelain Corp. 
Kortick Manufacturing Company (U.S. Pole Line Construction supplier)
Koppers Company Inc.
Koster's Potteries/Koster's Premier Potteries (Australian Insulator maker)
Kronacher Porzellanfabrick (Germany)
Kutnetsoz (Russia)
L. & F. De Fuisseaux Fabricants Baudour (Belgium)
L.G. Tillotson & Co.
L.S. Brach Mfg. Corp. (Radio strain insulators and lightning arrestors)
LTL Mfg. Corp. (Taiwan)
Lancaster Glass Works
Langdon & Hughes Electric Supply Co., Utica, NY
Langenthal (Switzerland)
Lapp Insulator Co.
Lawrence Electric Co., F.D
Lawrence Grey
L'Electro Verre (France)
Lenox China Co.
Leviton Manufacturing Company, Inc
Lewis, Edwin Co.
Lima Insultor Co.
Line Material Co.
Locke, Fred M.
Locke Insulator Corp.
Louisville Glass Works
Louthan Mfg. Corp.
Loveless Antenna Inc.
LTL Mfg. Corp. (Taiwan)
Lynchburg Glass Corp.
Lyndeborough Glass Co.
Lynon, James B. & Co.
M.A. Buell
Macallen Co., Boston, MA
Macintyre, James & Co., Ld. (England)
MacLean Power Systems
Majestic (Grigsby-Gruno)
Maltsov (Russia)
Manhattan Electrical Supply Co. (MESCO)
Manifattura Isolatori Vetro Acqui Terme S.p.A. (MIVA) (Italy)
Marks Products Co.
Marshall-Wells Co.
Marshall-Wells Hardware Co.
Maryland Ceramic and Steatite Co., Inc.
Maryland Lava Co.
Masnieres (Verreries de Masnieres) (France)
Massachusetts Glass Co.
Max Engels (Germany)
May and Bigley, Inc., Bedford, PA - Pin Maker
Maydwell & Hartzell, Inc .
Mayer and Englund Co.
Mayur Electro Ceramics Pvt. Ltd. (India)

McBride Glass Works
McCarthy Bros. & Ford
McKee & Co.
McLaughlin Glass Co.
Medbury Insulation
Mehr Glass Factory (Iran)
Meister International, LLC
Mercer Porcelain Co., Trenton, NJ
Mersick, C.S. & Co., New Haven, CT
Mesa, Fernando C. Company
Metropolitan Electric Co.
Metsch Refractories Co., East Liverpool, OH
Micanite and Insulators Company, Ltd. (England)
Mindrum Persion Products
Mine & Smelter Supply Co.
Mogadore Insulator Co., Mogadore, OH
Morris Collapsible Ball Antennas
Mt. Pleasant Glass Works
Mykroy/Mycalex Ceramics
National Ceramic Co.
National Company
National Electric Porcelain Co.
National Electric Products Co.
National Electrical Supply Co., Washington, DC
National Insulator Co.
National Porcelain Co.
National Tile Co.
New England Glass Co.
New England Glass Mfg. Co.
New Granite Glass Works
New Haven Clock Co.
New Haven Porcelain Co.
New Jersey Porcelain Co.
New Lexington High Voltage
New Zealand Insulators
Newell Porcelain Company, Inc.
NGK Insulators Ltd.
NGK-Locke, Inc.
Nikdim (Bulgaria)
Nilsen, Oliver J. & Co. Pty. Ltd. (Fitzroy, Victoria, Australia)
Nilson Porcelains, Pty, Ltd. (Australia)
Nippo (Japan)
Nord-Verre (France)
Norek Technique Fabricken (Norway)
North American Glass Co.
Northern Electric Co., Montreal, Canada
Northwestern Electric Equipment Co., Brooklyn, NY
Novelty Glass Co.
Nu-Blac (see Fleron)
Oakman Mfg. Co.
Ohio Brass Co.
Ohio Electric Porcelain Co. (East Liverpool, OH)
Ohio Insulator Co.
Ohio Porcelain Co.
Ohio Valley Glass Co.
Oliver Electric Manufacturing Co .
Oliver Iron and Steel Corporation
Opalescent Glass Co.
OTE (Organization Telephones Ellas) (Greece)
Osaka Togyo Kaisha, Ltd. (Japan)
Owens-Illinois Glass Co.
Oy Wartsila Ab Turku Pottery (Finland)
Pacific Clay Products
Pacific Electric Manufacturing Company (San Francisco, California)
Pacific Glass Works
Paiste, H.T. Co.
Parker, J.H.& Son, Parkersburg, WV
Partrick & Carter
Parvillee (France)
Pass & Seymour 
Patel Wire Industries Prop. Patel Enterprises Pvt. Ltd. (India)
Paul Seiler Electrical Works
Peach Porcelain Co.
Pearl Co., Wm. H., Indianapolis, IN
Peirce Specialty Co.
Perla Liza Industria Columbiana Materiales Electricos Limitada (Columbia)
Permali Limited (England)
Peru Electric Mfg. Co.
Petrel (Buenos Aires, Argentina)
Pettingell-Andrews Company
Philmore Mfg.
Pilkington Brothers, Ltd. (England)
PINCO (Porcelain Insulator Corp.)
Pinder, Bourne & Co. (England)
Pingxiang Porcelain Insulator Works (China)
Pittsburg High Voltage
P.L.M. Products
Plastic Insulator Co.
Porcelain Insulator Corp.
Porcelain Products, Inc.
Porceram (Argentina)
Porter, H.K. Co.
Porter & Berg Co.
Porter & Ross, Inc
Porzellanfabrik Hermsdorf (Germany)
Porzellanfabrik Kahla, Filiale Hermsdorf Klosterlausnitz (Germany)
Prather Brothers
Preformed Line Products, Co., Cleveland, Ohio
Premier Pottery, Koster's (Australian insulator manufacturer)
Pringle Electrical Mfg. Co.
Pyrex (see Corning Glass Works)
Quanah Co., Paoli, PA
Quam-Nichols Co.
R. Good Jr.
R. Thomas & Sons Co.
Rabone Feeze & CIE (Australia)
Radio Central
Radio Manufacturers' Supply Co.
Radio Receptor Co.
Radio Specialty Co. (Rasco)
Rajeev Industries (India)
Ravenswood Porcelain Co.
Reid Bros. (England)
Reliable Electric Co.
Rhein-Westfalishe Isolaboren Werke (Germany)
Rheinisch-Westf. Isolatoren G m b H. (RWI) (Germany)
Ricardo Dos Santos Gallo, Fo., Lda (Portugal)
Richard Ginori (Italy)
Richmond Glass Works
Ridlon, Frank Co., Boston, MA
Riverside Company (U.S. company with a controlling interest in Porcelain Products, Inc.)
Rochester Electrical Supply Company
Rörstrand (Sweden)
Rosenthal Insulators (Selb Bavaria Germany)
Rosenthal-Stemag-Technische Keramic (Germany)
Rosenthal Technische Werke
Rosenthal Technik AG (Germany)
Rutherford, George Co. 
S.F. Radio
S. Fobes & Co. (U.S. Electrical Distributor, possibly of S.F. insulators but also of Hemingrays)
S. H. Supply Co., Denver, CO.
Sackett Mine Supply Co.
SAG Ceramics Ltd. (South Africa)
Saint Johns Glass Co. (Canada)
Saint Louis Lightning Rod Co.
Sandwich Cooperative Glass Co.
San Francisco Glass Works
San Francisco & Pacific Glass Works
Santos Barosa & Co., Lda (Portugal)
Saunders, J.E. & Co. (U.K.)
Saxonburg Potteries
Sediver (French insulator manufacturer)
Scott & Fetzer Co.
Security Insulator Co.
Seiler, Paul Electrical Works
Semiconductro Mfg. Corp.
Shea & Stevens Co.
SiChuan YiBin Global Group, Ltd.
Siemens (Germany)
Siemens and Halske (Germany)
Siemens-Schuckertwerke Aktiengesellschaft (Germany)
Slater, N. Company Limited
Smith & Stone, Ltd. (Canada)
Snyder-Hunt Co.
Societe Anonyme Des Annciennes Usines De Fuisseaux a Baudour (Belgium)
Societe Anonyme de Verrerie Industrielle (France)
Societe Francaise de L'Ambroine (France)
Sociedad Anonima Fabrica National de Vidrio (SAFNV) (Uruguay)
Sociedad Industrial Ceramica Argentina
Societe H. Parra Et. Cie (France)
Southern Electrical Porcelain Works
Southern Porcelain Co.
Specialty Porcelain Works
Square-D Co.
St. Johns Glass Co. (Canada)
St. Louis Lightning Rod Co.
Standard China Works
Standard Electrical Products
Standard Glass Insulator Co.
Stanley & Patterson, Inc., New York.
Star Glass Works
Star Porcelain Co. Trenton, NJ
Steatit Magnesia (Germany)
Steatite & Porcelain Products Ltd. (U.K.)
Stearling Glass Co.
Steward Mfg. Co.
Steward-Howland Co.
Stewart, Frank H. Electric Co., Philadelphia, PA.
Stickla Turda (Romania)
Stocker & Co. Teleph und Telegraphenwerke
Stromberg-Carlson Telephone Manufacturing Co.
Stupakoff Ceramic & Mfg. Co.
Suisse Langenthall (Switzerland)
Sun Electric Insulator & Apparatus Manufacture Ltd (China)
Sun Electrical Co., Ltd., London, England
Sun Porcelain Co. 
Sunshine Potteries (Australia)
Superior Aerials
Superior Porcelain Co.
Superior Steatite & Ceramics Corp.
Superior Technical Ceramics Corp.
Suzhou Porcelain Insulator Works (China)
Swan-Haverstick, Inc.
Sydenham Glass Co. (Canada)
Synthetic Products Manufacturing Corp.
Taffel, Herman C.
Talley Industries
Taylor, Tunnicliff & Co., Ltd. (England)
Teal, Frank C., Co.
Technical Cermaics Lava Corp.
Telefunken Geselleschaft fur Drahtlose Telegraphie m.b.H. (Germany)
Telegraph Manufacturing Co., The (England)
Temiskaming & Northern Ontario Railway (T. & N.O. Ry) (Canadian Railroad)
Texas Arm & Pin Co.
Thames Glass Works
Thomas, R. & Sons Co.
Thor Ceramics, Inc., Bloomfield, NJ
Tienta (Taiwan Chican)
Tiger Industrial Ceramics Co., Limited (China)
Tillotson, L.G. & Co.
Toronto Glass Co. (Canada)
Transadean Associates, Inc.
Trenle Porcelain Co., East Liverpool, OH
Trenton China Co.
Trenton Elec. & Conduit Co.
Trenton Porcelain Co.
Trumbull Radio Insulators
Tufnol, Ltd. (Birmingham, England)
Turku Potteries (Finland)
Union Electric Co.
Union Electrical Porcelain Co.
Union Porcelain Works
Union Pottery
U.S. Electric Porcelain Co.
U.S. Porcelain
U.S. Stoneware Co.
Universal Clay Products Co.
Valley Design Corp.
Valverde Glass Works
Verbano Ceramics (Italy)
Verbano Porcellana di Laveno (Italy)
Vereinigte Glaswerke (VEGLA)
Verlica Belgium (Belgium glass insulator manufacturer)
Verreries Charbonneaux (France)
Verreries d'Albi (France)
Verreries de Folembray (France)
Verreries de Reims (France)
Verreries de Masnieres (France)
Victor Insulators, Inc.
Victor-Bernard Industries, Inc.
Vidreria Industria Figuerras Oliveiras S.A. (Brazil glass insulator manufactuerer)
Vidriera Monterrey (Mexico)
Vidrart, S.A.
Vidreria Industria Figuerras Oliveiras, S.A. (VIFOSA) (Brazil)
Vidrios Bogota (Columbia)
Virginia Glass Mfg. Co.
Virginia Pottery Co.
W.B. Mfg. Co.
Wade Potteries
Walker, Henry L. Co.
Ward Products Corp.
Washington Porcelain Co., Washington, NJ
Wesco Supply Co., St. Louis, MO
Wessel-Draeger Vertriebs GMBH., Bonn, Germany (General Distributers for RWI)
West Virginia Porcelain Co.
Western Electric Mfg. Co.
Western Flint Glass Co. 
Western Glass Manufacturing Co. (WGM)
Westfalia-Surge Inc.
Westinghouse Electric Corp.
Wheeling Tile Co.
Whitall Tatum Co.
Wilkinsons, A.J. & Co.
Wireman, Inc., The
Wisconsin Ceramic Products
Wisconsin Porcelain
Woodruff & Co.
Wormser, E. & Co.
Xi'an XD High Porcelain Insulator Co., Ltd. (China)
Yahr-Lange Inc.
Zsolnay Ceramics (Hungary)
Zundel y Cia. Limitada [Zundel and Company, Limited] (Columbia glass insulator maker)
Zundel Industria Colombiana Materials Electricos [Zundel Electric Materials Company of Columbia]

This page updated April 24, 2012