Nail Knobs, Split Knobs

and Other House Wiring

Knob Insulators

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Nail knobs were commonly used for house wiring, which had an insulated covering.  Wall tubes were also used to go through studs and rafters.  Here are few photos that show how they were used.  Not all the split knobs shown on this web page are "nail knobs" as many styles were intended to be mounted with wood screws.

 

 

Below is a listing of nail knobs in my collection.  Please note the following legend when reading the table.  Click on the Category Number to see a photo of the insulator or go to the pages with photos of all insulators listed below:

 

R = round (standard diameter) nail knob

RR = round reversible knob

O = oval

S = square or rectangular

SR = square or rectangular reversible knob

/ = marking on opposite side

// = marking on bottom

 

No. No. MARKING Marking Type Patent Company Notes
    Nail Knobs        
R-01 R-01.jpg (16452 bytes)R-01_Macomb.jpg (15011 bytes) MACOMB emb   Illinois Electric Porcelain Co.  
R-02 R-02.jpg (15913 bytes)R-02_Macomb.jpg (14786 bytes) BMOCAM (Macomb) emb   Illinois Electric Porcelain Co. matching V-grooves on cap and base
R-03 R-03.jpg (17253 bytes)R-03_Superior.jpg (17387 bytes) SUPERIOR / 5½ emb   Superior Porcelain Co. corrugated cap and ring outside; captivated nail
R-04 R-04.jpg (16611 bytes)R-04_WTCo.jpg (15619 bytes) W. T. CO. PAT'D JULY 23 1919 emb 1,311,483 Wheeling Tile Co. radially ribbed cap
R-05 R-05.jpg (15749 bytes)R-05_PPInc.jpg (16191 bytes) P.P. INC. / ALLIGATOR emb   Porcelain Products Inc. captivated nail; corrugated under cap with raised ring around outside
R-06 R-06.jpg (17954 bytes) N-N       cone top, cone recessed bottom; corrugated cap with raised ring around outside; captivated nail
R-07 R-07.jpg (16737 bytes)R-07_SPW.jpg (15925 bytes) SPW / UL / 110 r-e   Specialty Porcelain Works concentric rings under cap; captivated nail
R-08 R-08.jpg (15631 bytes) N-N       rounded top, cone recessed bottom
R-09 R-09.jpg (16307 bytes)R-09_btm.jpg (20367 bytes) N-N       rounded top, deep recessed bottom
R-10 R-10.jpg (15719 bytes)R-10_CPCO.jpg (16642 bytes)

R-10_open.jpg (25887 bytes)

 WEDGE / C. P. CO. PATD; (top of bottom part: PAT. APR. 27, 1909) r-e 1,218,181 Cook Pottery Co. 3-slot recessed bottom; radial ridges under cap; also patent 919,386
R-11 R-11.jpg (15177 bytes)R-11_Monowatt.jpg (17098 bytes)

R-11_open.jpg (21809 bytes)R-11_top.jpg (13792 bytes)

 MONOWATT emb   ?? concentric ring under cap; captivated nail
R-12 R-12.jpg (15840 bytes)R-12_FEDCO.jpg (17514 bytes)

R-12_open.jpg (26002 bytes)

 FEDCO emb   Federal Porcelain Co. corrugated cap; captivated nail
R-13 R-13.jpg (17631 bytes)R-13_TriangleM.jpg (18020 bytes) Triangle M PATD FEB 3 1920 // BULL DOG r-e 1,329,656 Illinois Electric Porcelain Co. captivated nail; radial ridges under cap
R-14 R-14.jpg (16293 bytes)R-14_Nailit.jpg (16655 bytes)

R-14_open.jpg (23598 bytes)

 NAILIT / PAT APPD FOR r-e   J. H. Parker & Son radially ribbed cap; captivated nail
R-15 R-15.jpg (16112 bytes)R-15_Brunt.jpg (16597 bytes)

R-15_btm.jpg (19585 bytes)

 BRUNT / CINCH // BRUNT emb   Brunt Porcelain Co. radially ribbed cap; captivated nail
R-16 R-16.jpg (16126 bytes)R-16_Macomb.jpg (15168 bytes) MACOMB emb   Illinois Electric Porcelain Co. ribbed channels in cap and base
R-18 R-18.jpg (15248 bytes)R-18_Brunt.jpg (14505 bytes) BRUNT (backward N) emb 917,207 Brunt Porcelain Co. 1" diameter, nail hole offset; matching V-grooves
R-19 R-19.jpg (15228 bytes)R-19_SPW.jpg (16729 bytes)

R-19_open.jpg (22339 bytes)

 SPW (inside a diamond) emb   Specialty Porcelain Works 3/4" diameter, unglazed
R-27 R-27-28.jpg (23158 bytes) (illegible patent date) emb 907,251 Colonial Sign & Insulator Co. specimen found at Colonial
R-28 R-27-28.jpg (23158 bytes) N-N   907,251 Colonial Sign & Insulator Co.  
R-30 R-30.jpg (17002 bytes)R-30_pat.jpg (18016 bytes) PATD - FEB - 3 - 1920 (circle) emb 1,329,656 Illinois Electric Porcelain Co. cap corrugated underneath; bottom unglazed; captivated nail
R-31 R-31.jpg (16644 bytes)R-31_Gripit.jpg (18005 bytes) GRIP IT / PAT. r-e   J. H. Parker & Son cap only
R-32 R-32.jpg (16835 bytes)R-32_APCo.jpg (19251 bytes) A. P. CO. G. E. CO. 9419 (circle) emb   Anderson Porcelain Co. cap only; 1-1/2" diameter
R-35 R-35.jpg (17966 bytes)R-35_Nailit.jpg (17254 bytes) NAILIT / PAT FEB. 3, 1920 emb 1,329,656   radially ribbed cap
R-36 R-36.jpg (17511 bytes)R-36_TriangleM.jpg (17527 bytes) Triangle M / BULL DOG r-e   Illinois Electric Porcelain Co. unglazed; radially ribbed cap; captivated nail
R-37 R-37.jpg (15889 bytes)R-37_PPInc.jpg (15787 bytes) P.P. INC. / ALLIGATOR / 5½ emb   Porcelain Products Inc. captivated nail
R-38 R-38.jpg (16863 bytes)R-38_TPCO.jpg (17196 bytes)

R-38_btm.jpg (18035 bytes)

 T - P - CO. / JIFFY / No 1 // PATD 12-8-03 emb 745,999 Trenton Porcelain Co. Patent shows a ball top part, but this is a standard-looking nail knob. Raised ring under cap; captivated nail
R-39 R-39.jpg (18318 bytes)R-39_NAT.jpg (17295 bytes) NAT. / READY / PAT / 2-3-20. emb 1,329,656 National Electric Porcelain Co. unglazed; radially ribbed cap; captivated nail
R-40 R-40.jpg (15766 bytes)R-40_TriangleM.jpg (15726 bytes)

R-40_BullDog.jpg (17411 bytes)

 Triangle M / PAT FEB 3 1920 // BULL DOG 98 r-e / emb 1,329,656 Illinois Electric Porcelain Co. radially ribbed cap
R-41 R-41.jpg (15657 bytes)R-41_GeePee.jpg (15000 bytes) GEE PEE emb   General Porcelain Co. radially ribbed cap
R-42 R-42.jpg (16209 bytes)R-42_Findlay.jpg (15614 bytes) FINDLAY / ALLIGATOR emb   Findlay Electric Porcelain Co. corrugated cap
R-43 R-43.jpg (14200 bytes)R-43_G.jpg (13329 bytes) G emb 917,207   1" diameter, nail hole offset; matching V-grooves on cap and base
R-44 R-44.jpg (16630 bytes)R-44_DPCo.jpg (15887 bytes) D. P. Co. / EVER / READY (in circle) r-e   Davidson Porcelain Co. concentric rings under cap
R-45 R-45.jpg (15797 bytes)R-45_T.jpg (14582 bytes) T emb   R. Thomas & Sons Co. 1" diameter, nail hole offset; matching slot
    Round Split Knobs, Oval Split Knobs, Round Reversible Split Knobs        
R-20 R-20.jpg (16853 bytes)R-20_F.jpg (17021 bytes)

R-20_btm.jpg (19068 bytes)

 F // F emb 464,770 Findlay Electric Porcelain Co. 1-3/8" diameter, caming groove
R-21 R-21.jpg (17249 bytes)R-21_GE.jpg (17793 bytes)

R-21_btm.jpg (18857 bytes)

 G. E. KNOB / PAT APLD FOR // 9352 emb   General Electric Co. 1-1/2" diameter
R-22 R-22.jpg (20011 bytes)R-22_GE.jpg (22294 bytes)

R-22_btm.jpg (25178 bytes)R-22_open.jpg (30654 bytes)

 G. E. KNOB // CAT. 6580 r-e   General Electric Co. 2" diameter
R-23 R-23.jpg (21934 bytes)R-23_PPInc.jpg (20810 bytes) P. P. Inc. emb     2" diameter; matching vertical groove on the side
R-24 R-24.jpg (20382 bytes)R-24_PPInc.jpg (21644 bytes)

R-24_btm.jpg (27636 bytes)

 P. P. Inc. / 9420 // P. P. Inc. / 9420 emb     2" diameter; matching vertical groove on the side
R-25 R-25.jpg (21335 bytes)R-25_GE.jpg (18940 bytes)

R-25_btm.jpg (23322 bytes)

 G. E. KNOB // CAT. 6580 emb   General Electric Co. 2" diameter
R-46 R-46.jpg (19301 bytes)R-46_GE.jpg (17290 bytes)

R-46_btom.jpg (18986 bytes)

 G. E. KNOB // E P emb / r-e   General Electric Co. 1-1/2" diameter
R-47 R-47.jpg (18658 bytes)R-47_GE.jpg (17654 bytes)

R-47_btm.jpg (20180 bytes)

 D. P. CO // 9419 emb / r-e   Davidson Porcelain Co. 1-1/2" diameter
R-48  

 

 PHILCO r-e   Philco Radio Corp. Black glaze
R-49

 

 PAT'D / 10-22-12. emb 1,042,372   1-1/8" diameter
R-50

 

 NAT / READY emb   National Electric Porcelain Co. 1-1/8" diameter; dot projections under cap
O-01

N-N     Colonial Sign & Insulator Co. similar to patent 806,588
O-02

T / PAT / 4803 / NO. 5½ emb 697,001 R. Thomas & Sons Co. reversible, oval; error date, should be 4-8-02
O-03

STAR // (embossed star) PAT DEC 5 05 r-e / emb 806,588 Star Porcelain Co.  
RR-01

.G. PAT APPD FOR (circle) emb     1-1/8" diameter; reversible
RR-02 BUCKEYE REGD (circle) PATD 12-31-12 / F (outer circle) emb 1,048,850 Findlay Electric Porcelain Co. reversible, crossover knob
RR-03 T P I / NO 1 / T / PAT / APR / 803 emb 697,001 R. Thomas & Sons Co. 1-3/8" diameter, reversible, error date, should be 4-8-02
RR-04 T / PATD 7-20 / 1915 emb 1,147,498 Trenton Porcelain Co. 1-1/8" diameter; reversible
RR-05 PAT. / APP.D. / FOR / G. (in circle, G inside circle) emb     1-1/8" diameter; reversible
RR-06 F / PATD / 12-31 / 12 (in circle) emb 1,048,850 Findlay Electric Porcelain Co. 1-1/8" diameter; reversible
RR-07 RR-07.jpg (16380 bytes)RR-07_F.jpg (16915 bytes) F / PATD / 12-31 / 12 (in circle) emb 1,048,850 Findlay Electric Porcelain Co. 1-1/4" diameter; reversible, crossover knob; error date 12-13 instead of 12-31
RR-08 RR-08.jpg (18943 bytes)RR-08_Thomas.jpg (21798 bytes) T P I / NO 2 / THOMAS / PAT / APR / 8 03 emb 697,001 R. Thomas & Sons Co. 1-3/4" diameter; reversible
RR-09   B&D PAT. / AUG. 13, 95 emb 544,501 Buffinton & Dow patent (licensed) 1-1/2" diameter; reversible; cleat patent
    Square Reversible Split Knobs, Misc. Knobs, and Square Knobs        
SR-01 U S / PATD / 2408 / 51611 emb 878,302 US Electric Porcelain Co. reversible
SR-02 Triangle M / PAT'D / FEB 9 / 1915 emb 1,127,776 Illinois Electric Porcelain Co. reversible
SR-03 U S / PAT'D (on short end) emb 878,302 US Electric Porcelain Co. reversible
SR-04 U S / PAT'D (on long end) emb 878,302 US Electric Porcelain Co. reversible
R-17 R-17.jpg (14487 bytes)R-17_parts.jpg (20479 bytes) IDEAL // PATENTED / 5 28 07 emb/r-e 855,208 Star Porcelain Co.  
R-26 R-26.jpg (18276 bytes)R-26_parts.jpg (24340 bytes) N-N   965,723 Paragon Electric Co. ball fits on top of the base
R-29 R-29.jpg (15383 bytes)R-29_btm.jpg (18456 bytes) PATENTED MAY 13 1902 (circle on bottom) r-e 699,761    
R-33 R-33.jpg (19581 bytes) PAT'D / JULY / 19 - 92 (on side) emb 479,134   Conover patent
R-34 R-34.jpg (18091 bytes)R-34_top.jpg (20253 bytes)R-34_btm.jpg (19337 bytes) POLK / PAT'D MCH 10 emb 724,329   three flanges on top for tying wire around the knob; saw-toothed bottom edge prevents turning
S-01

S-H Co. / No. 1 // A. P. C. L. / Pat. / Mar. 1, '04 emb 753,399   Snyder-Hunt Co.
S-02

S-H Co. / No. 1 // MACOMB / PAT / MAR-1-04 r-e 753,399 Illinois Electric Porcelain Co. Snyder-Hunt Co.
S-03

MACOMB. / PAT. / MAR-1-04 // S-H. co. / No. 1. r-e 753,399 Illinois Electric Porcelain Co. Snyder-Hunt Co.
S-04

S H co. / no 1. // MACOMB. / PAT. / MAR-1-04 r-e 753,399 Illinois Electric Porcelain Co. Snyder-Hunt Co.
S-05 S-05.jpg (25105 bytes)S-05_Klingel2.jpg (30151 bytes) Triangle M / PARALLEL / KNOB / PAT. APPL. FOR // E. L. KLINGEL / ST. PAUL emb / r-e 2,307,277 Illinois Electric Porcelain Co.  

 

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