Lead encased electrical cabling- Early Electrical Cabling Systems

On a  home inspection I ran into early lead encased or lead sheathed electrical cable. Something you do not see much of, at least not here. This was an early form UF cable (underground feeder).

I scraped the side to show the lead mark

Lead encased cable was  used for underground installations back in the early to mid-20th century in residential and there maybe local variation on timeframes. From what I could find it seems to be more common in England than here. It origins was derived from the early days of telegraphy.

From research lead encased cables  were used extensively on early telephone cabling systems. There is record of using lead to encase conductors back to “Professor Morse”, yes the same Morse of Morse Code fame.

This type of cable encasing (lead sheathing) is still in use today in certain applications. It is estimated that 10% of overland and underseas cables are sheathed with metal, usually Lead.

From the EMF Yearbook of 1921, An encyclopedia of current information about each branch of the electrical industry.

Cable, LEAD-COVERED, POWER TYPES-

Cables used for underground systems serving power in lighting are of lead covered or sheathed type, insulated with oiled paper varnished Cambric or rubber.  The conductors are called single, duplex, triplex or multiplex according as there are one three or more separately insulated conducting cores.

Experience has demonstrated that whenever cable is to be used in underground conduits, are exposed to acid gases, extreme temperature changes or other destructive agencies it should be encased in a lead sheath.  For this reason much of the cable used in telephone, railway signaling another signal systems both aerial, submarine and underground, and light and power wiring underground and in damp places etc. is enclosed in a lead sheath.  The conductors may be either rubber, cambric or paper insulated twisted together with jute fibers giving a flat cable.  Lead covered power cables and telephone cables are described separately below.

The lead sheath is applied by passing the cable through a die surrounded by molten lead which is kept at a temperature just sufficient to maintain it in a molten state a slight decrease in temperature causing it to solidify.  The lead is applied under hydraulic pressure and is formed into a smooth uniform coating by the die, solidifying just as it leaves the die.  The cables fed through slowly sometimes directly from a drying oven as with paper insulated and dry core or cables and as it emerges from the die coiled on a large real about 15 to 20 feet away the time taken from a distance being sufficient to permit the sheath to harden.

EMF Electrical Year Book, Volume 1

Lead cable connected at junction box

One of the things I enjoy about perform home inspection is finding these artifacts from a time gone by.

“Knowledge has to be improved, challenged, and increased constantly, or it vanishes.”

Peter Drucker

NCW Home Inspections, LLC  is a Licensed Washington State Home Inspection service located in Wenatchee Washington serving Chelan County, Douglas County, Kittitas County, Okanogan County and Grant County Washington and the cities of Wenatchee, Leavenworth, Cashmere, Oroville, Cle Elum, East Wenatchee, Quincy and many more…  

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