Are there around a hundred miles of wire in a car? No, there only are about three.

 

 

 

 

 

 

 

 

 

 

I heard part of the first presentation at the Coast-to-Coast AM radio show on December 6, 2022 by James Rickards titled Supply Chain Disruptions. Their web page has this claim:

 

“He forsees a return of manufacturing jobs to America because of global problems….

As an example of a breakdown, he cited the automotive industry, which uses around 100 miles of wire in each car, and these are run through plastic conduits. Such conduits were manufactured in Ukraine, and their unavailability during the war caused BMW and Volkswagen to shut down major assembly lines until they could find a new source.”

 

I’m a retired engineer, and to me 100 miles sounds way too big. Before we try to find a source for how much wire there is, let’s look at that amount as a Fermi problem and make a Fermi Estimate, which an article at Brilliant describes as:

 

“…one done using back-of-the-envelope calculations and rough generalizations to estimate values which would require extensive analysis or experimentation to determine exactly.”

 

According to Wikipedia, a Volkwwagen Jetta (shown above) is 185 inches (15.4 feet) long, 70.8 inches wide, and weighs a maximum of 2970 pounds. The NAPA Know-How Notes: Automotive Wiring Guide web page says typical copper signal wire is #18 gauge, which according to another web page at WireAndCableYourWay has an outside diameter of 0.095 inch, and a weight of 0.009 pounds per foot.

 

A hundred miles is 528,000 feet, and when we divide that by 15.4 feet, we get 32,285 car-lengths of wire for our Jetta. That seems like a lot more wire than necessary for connecting everything we might imagine in a car.

 

When we lay those wires side by side like a ribbon, it would be 32,285 times 0.095 or 3,257 inches wide, or 46 times the width of the car. If we stack them up (at the width of the car), the height would be 46 times 0.095 inches or 4.37 inches tall.

 

What about the weight? 528,000 feet times 0.009 pounds per foot is 4752 pounds – or 1.6 times the weight of the Jetta. That weight makes no sense whatsoever.

 

There is an article by Christina Amann and Nick Carey of Reuters on March 2, 2022 titled Ukraine invasion hampers wire harness supplies for carmakers which instead says:

 

“A wire harness is a vital set of parts which neatly bundle up to 5 kilometres (3.1 miles) of cables in the average car.”

 

So the 100 miles claimed at Coast-to-Coast was over 32 times too high. 3.1 miles of wire would weigh a much more sensible 147 pounds. And there would be 1,063 car lengths of wire – not 32,285.

 

There is another article by Susan Rambo in Semiconductor Engineering on March 12, 2019 titled Shedding pounds in automotive electronics which has the following detailed information:

“…The traditional wire harnessing takes up a lot of space and weight even in compact cars. ‘The wiring harness is one of three heaviest subsystems in many vehicles - as much as 150 lbs in highly contented vehicles - and it’s very typical for the average vehicle to have 100 - 120 lbs of wire harness in the vehicle. These vehicles weigh on average around 3,500 lbs,’ said Mentor’s Burcicki. ‘Today’s luxury cars contain some 1,500 - 2000 copper wires - totaling over 1 mile in length. To put that into perspective, in 1948, the average family car contained only about 55 wires, amounting to total length of 150 feet.’ ”