French Distribution Towers

French power distribution towers and their unique glass insulating discs have fascinated this writer for several years, resulting in a lot of time being spent researching and photographing these old towers.

French distribution towers are the equivalent of American electrical mini-substations but very different in design. Instead of pads of electrical transformers, etc. enclosed by chain link fences and barbed wire, French power distribution substations consist of tall, solid concrete towers that utilize four sizes of glass insulating discs at the top to insulate primary and secondary power lines entering and leaving the towers. Other than the glass discs, which are firmly cemented on both sides into openings at the top of the towers, the only opening to these concrete towers is a thick, solid metal door at the base, making the towers very secure.

French distribution tower 
A brick beauty, the only brick 
tower ever observed

French distribution towers came into existence in the 1930's and 1940's but the majority of distribution towers were built during the reconstruction of France after the second world war. At one time, every town that had electricity had a distribution tower and larger towns and cities had two or more distribution towers. All transformers and electrical equipment used for reducing high voltage transmission lines into low voltage lines for local power use were hidden inside these tall towers. Typically, 20,000 volt transmission lines would enter the tower through large glass insulating discs and 220 or 380 volt secondary power lines for local use would exit the tower through smaller insulating discs on a different side of the tower.

4 sizes of glass insulating disks 
CD 1170 - 1173

Folembray, Isorex and L' Electro Verre were the "big three" of French glass insulator production and all three companies are believed to have produced the various size insulating discs. Folembray and L' Electro Verre embossed discs, along with some unembossed discs, have been recovered but, to date, an Isorex embossed disc has yet to be found, although old Isorex catalogs show the discs being available in several sizes. Hopefully, an Isorex embossed disc will be recovered in the near future.

CD 1170's in tower

Four distinct sizes of these glass insulating discs were used in distribution towers throughout France. After careful consideration of technical information, detailed photographs, etc., Mr N. R. Woodward has assigned the following CD numbers to these insulating discs.

CD 1170 : D - 1 disc, 5-1/4" diameter x 7/8" thick, 1 pound. The smallest of the four discs, the CD 1170's were used to insulate low voltage lines exiting the towers for local power use. All CD 1170's found to date have been embossed L' Electro Verre/D-1 or have been unembossed.

CD 1171 : D - 2 disc, 8-5/8 " diameter x 1-3/8 " thick, 3.3 pounds. Next to the smallest disc, the CD 1171 's were also used to insulate low voltage lines exiting the towers. Only five CD 1171's have been recovered to date, a Folembray/No 61, an L' Electro Verre/122 and three unembossed ones.

CD 1172 : D - 3 disc, 12-5/8 " diameter x 1-1 /2 " thick, 7.7 pounds. A few D-1, D-2 and D-4 discs were acquired from EDF (Electricite de France) contacts over the last few years but a D-3 size disc was unknown. Due to the tremendous size difference between the D-2 and D-4 discs, 8-5/8" versus 16-5/8 ", this writer was convinced that a D-3 size disc must exist. After discussing this concern with Mr. Woodward, the CD 1172 number was left open when Mr. Woodward assigned the rest of these CD's in November, 2005. While visiting in the south of France in February, 2006, a good EDF contact surprised this writer with three D-3 discs embossed L' Electro Verre/ 123, the only three CD 1172's known at this time. This friend had spent most of a day at the top of a tall ladder tediously chipping the cement away to free these glass jewels from the top of an old distribution tower where high voltage lines had once entered the tower through these discs.

CD 1173 : D - 4 disc, 16-5/8" diameter x 1-1 /2" thick, 13.5 pounds. Seven of these huge, impressive D-4 discs have been acquired from EDF contacts to date, five in a blue aqua color embossed L' Electro Verre/D-4 and two unembossed ones in a pale green tint filled with hundreds of tiny seed bubbles. 

CD 1173 in unusual designs

(4) CD 1177's in wall of old power plant

Large Folembray D-4 size discs have been observed in a couple distribution towers but they have proved impossible to acquire to date.

A few words on the difficulty of acquiring these beautiful, old glass discs might be in order. Electricite de France (EDF) is the only power company in France and is an integral part of the government. With seventy-eight percent of all electrical power in France being produced by nuclear power plants, it is easy to understand the high degree of security and access restrictions that apply to anything related to EDF throughout France. This definitely applies to all distribution towers, even the abandoned ones where all power lines entering and exiting the towers have been cut and removed. Even for EDF personnel who might have keys and legal access to these towers, a tall ladder, specialized tools and a lot of time and patience would be required to successfully remove a disc.

CD 1177 Folembray // E2

These distribution towers are fast becoming relics of the past as American style mini-substations are being built throughout France. It is estimated that over fifty percent of the distribution towers are no longer in use due to the modernization of the electrical power system. Many abandoned towers have been bulldozed down and many of the glass discs in other towers have been cracked or damaged by linemen hastily removing re-useable equipment.

CD 1177 : three piece, cemented disc assembly, 16- 5/8" diameter x 10- 1/4" center height, 21.4 pounds. These largest and most impressive of glass disc units were apparently used only on actual power plants where high voltage transmission lines exited the plants. In nineteen extended insulator research trips throughout France, this writer has only observed these huge units at three old power plants. A unique, L' Electro Verre // D-4 CD 1177 unit was received from an EDF contact in eastern France in March, 2004, the first CD 1177 ever seen by this writer. Since then, five CD 1177 units embossed Folembray // E2 have been recovered from EDF contacts and brought safely back to Alaska.

D - 3 and D - 4 Large Disks

Large CD 1173 D-4 discs have been observed in abandoned towers in unusual designs and colors, as is also true with the smaller discs. Much more time will be spent on future trips to France in trying to locate an Isorex embossed disc and in attempting to find different designs and embossings of all of these fascinating, historical glass insulating discs.

FRENCH DISTRIBUTION TOWERS AND CONNECTIONS