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A recent environmental hazard has just been uncovered this past week by the Wall Street Journal:

"America Is Wrapped in Miles of Toxic Lead Cables" https://www.wsj.com/articles/lead-cables-telecoms-att-toxic-5b34408b https://archive.is/MA0wG

The Journal series on this topic mentioned the use of lead (Pb) as a uniquely anti-corrosive cladding for cable at the time.

I have 2 questions:

  1. Why was rubber cladding not used during the Bell Telephone cable laying era? They were surely aware of Rubber (Model T Fords had vulcanized rubber tires around the same time in history.) Also, my calculations indicate that using nitrile rubber cladding would have been 1/8th as expensive as lead for the same job.

the following pricing is for background reference, on the expense argument:

•Price of Rubber ~'$$800/mt

•Price of Lead ~'$500/mt (note the price of lead jumped, ironically, after the 2006 EU RoHS to it's present levels)

•Density, ρ(lead) = 11343 kg/m^3

•Density, ρ(nitrile rubber) ~1100 kg/m^3

(Since the commodity price is quoted per 1000kg of mass, any given annular volume of cladding on the cable works out to ~1/8th the price using rubber)

  1. Given that nonetheless, Lead was indeed used as the best non corrosive cladding (and the ability to solder lead to lead for common earth ground), is there a similar telephony origin lead-epidemic in other countries that were leading industrializers, historically? For eg, Sweden pushed out Bell Telecom in burying cables in Sweden in the 1900s. Did they use lead cladding? Japan? Do other countries have a similar lead problem?

please, i have searched to find the proper forum on the stack universe for this question, but this stack seems to be the best place. thank you.

Kiers
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    Note: Nitrile rubber wasn't produced until halfway through the "Bell cable laying era". First low-permeable rubber not long before Nitrile. Guta-percha with lead weights was used before suitable rubber was developed. Note: post 1960 lead shielding was replaced with aluminum where gas-tight seal is required. – david Jul 18 '23 at 04:47
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    Lead was used 2000 years ago by the Romans... Perhaps the journalists just needed some column inches as the issues with lead are well-known. – Solar Mike Jul 18 '23 at 08:01
  • Are the prices for lead & rubber you quote the prices when the cable was laid or more recent prices? – Fred Jul 18 '23 at 08:15
  • @Fred, the prices were reasonably far back from present times because public safety injunctions against the use of lead raised the price of lead. So, i just took a rough proxy by going back 20 years or so to a time with a stable plateau in historical price, just for first cut analysis. – Kiers Jul 18 '23 at 15:35
  • @SolarMike, yes, you're point is well taken. The talk on the WSJ comment sections is that everyone has switched to "wireless", nobody uses landlines anymore, therefore, they are bringing this up now, to begin the demise of the landline assets once and for all. – Kiers Jul 18 '23 at 15:36
  • We're going to wireless for the last mile -- but that doesn't mean that the signal doesn't go through a whole lot of wire and/or fiber getting from one cell tower to another! – TimWescott Jul 18 '23 at 16:04
  • I guess you are not worried because at construction time ; car gas tanks were lead coated ( aka terne plate) and car hydraulic brake lines. were lead plated . – blacksmith37 Jul 18 '23 at 18:59
  • These are hundreds of miles of trunk line carriers -- not millions of miles of subscriber lines. Some of them were replaced by microwave (a kind of wireless...), but now they are replaced by fibre. I think some fibre had lead sheath, but not so much now. – david Jul 20 '23 at 03:26

2 Answers2

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Since you mention the Model T Ford in regards to vulcanized rubber, I'm using the 1920s as a reference period.

Various newspaper articles give the price of lead in London from 1913 to 1925 and for rubber in 1925.

Despite reaching a high of £44 (44 British pounds) per British ton (2240 lb) on December 30, 1924, the forward price was £42/2/6 (44 pounds 2 shillings and 6 pence) per British ton.

In July 1925, the price for rubber for deliveries in 1927 was 2/2 (2 shillings and 2 pence) per pound, after reaching a high of 4/- (4 shillings) per pound.

There are 2240 pounds (weight) in a British ton.

There were 20 shillings in a pound (currency) and 12 pennies in a shilling, resulting in 240 pennies per pound currency.

Now, 2/2 is 26 pennies (2 * 12 + 2 = 26), resulting in a price of 58,240 pennies per British ton of rubber (26*2240 = 58,240), or £242/13/4 per British ton (242 pounds, 13 shillings and 4 pence).

This was about 5 times the price of lead for the period.

Fred
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This applies to power cables rather than comms cables, but it illustrates the problems:

"Water treeing is the major aging mechanism in wet-designed cross-linked polyethylene (XLPE) cables causing a reduced lifetime."

"terrestrial polyethylene power cables without hermetic sheaths when directly buried in moist soil are subject to tree growth and failure"

david
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