Wire and Cable: How old is Old?

Status
Not open for further replies.
R

richo

Member
I keep hearing that if you leave old cables (i.e. 208v, 500mcm) alone in conduit they should last and last.
Varnished covered cables from 1929 may still look good and megger out OK but:
When will the next upgrade to the wiring occur?
Can you assume an owner will replace the cable before the next ninety years go by?
Is 180 year old wiring OK in anybody's mind?

I have read reports by Engineers and heard Architects repeat the same mantra of leaving old cables lie and still using these antiques.

Am I crazy to insist on replacing cables in excess of 50 years old?
Is there a better number?

Thank you in advance.
 
LarryFine

LarryFine

Master Electrician Electric Contractor Richmond VA
Location
Henrico County, VA
Occupation
Electrical Contractor
Welcome to the forum! :)

richo said:
Can you assume an owner will replace the cable before the next ninety years go by?
Click to expand...
I don't replace anything based on its age alone.

Is 180 year old wiring OK in anybody's mind?
Click to expand...
If 90-year-old wire can be meggered, I imagine 180-year-old wire can.




If they still have meggers.




If they still have wire. :cool:
 
Jraef

Jraef

Moderator, OTD
Staff member
Location
San Francisco Bay Area, CA, USA
Occupation
Electrical Engineer
In 1809, a crude telegraph was invented in Bavaria by Samuel Soemmering. He used 35 wires with gold electrodes in water and at the receiving end 2000 feet the message was read by the amount of gas caused by electrolysis. In 1828, the first telegraph in the USA. was invented by Harrison Dyar who sent electrical sparks through chemically treated paper tape to burn dots and dashes.
Click to expand...

Must have had wires in 1809 in Bavaria, but looks like they had to use paper tape here in the US even 19 years later according to this...

Then things got better the following year.
In 1830, an American, Joseph Henry (1797-1878), demonstrated the potential of William Sturgeon's electromagnet for long distance communication by sending an electronic current over one mile of wire to activate an electromagnet which caused a bell to strike.
Click to expand...

There's your wire in 1830!
:grin:
 
R

richo

Member
augie47 said:
I agree with Larry.
Worry more about your being around to replace it IF and WHEN it fails.

I won't even begin to discuss "OLD"...:)


If the 90 year old wire fails in 10 years I'll be around and I think they will still have lawyers.
Regarding 180 year old wiring, if the owner is doing the first major upgrade after 90 years, I doubt the next upgrade will occur much before another 90 years.

Thanks for all the humor, but I was hoping this was a real technical forum concerning the age of insulation and possible the copper degradation over time.
Click to expand...
 
B

broadgage

Senior Member
Location
London, England
Rubber perishes if exposed to air and sunlight, and I doubt that 50 year old rubber cables with exposed insulation or sheathing would still be servicable.

Rubber if protected by a lead outer covering, and not overloaded or damaged should last almost indefinatly. The problem would be at terminations were the rubber is exposed to the air and has probably perished. It might be possible to repair perished insulation at the ends with brush on insulating compounds or varnish, or by applying heat shrink tube or self amalgamating tape.

Oiled paper insulation, if protected by a suitable outer covering appears to last almost indefinatly.
Lead sheathing lasts almost indefinatly.

PVC insulation has now been in use for about 60 years, and cables that old seem as good as new, both by electrical testing and physical inspection.

In the case of small cables with many terminations, as used for house wiring, replacement is the often the best option.
In the case of large cables when the cost of replacement can be tens of thousands of ?/$, then re use is more worthwhile.

Here in London some POCO mains in the streets are at least 70 years old and appear still to be sound.
Failures occur regulary, but dont seem to be age related, water ingress at defective joints and damage during excavations acount for most failures, not old age.
 
480sparky

480sparky

Senior Member
Location
Iowegia
richo said:
............Regarding 180 year old wiring, if the owner is doing the first major upgrade after 90 years, I doubt the next upgrade will occur much before another 90 years..........
Click to expand...

Why? You think the same people are going to still own it 90 years from now?
 
Pierre C Belarge

Pierre C Belarge

Senior Member
Location
Westchester County, New York
Concern about the integrity of conductor insulation should be for all conductors installed. I have seen 'old' wiring look and test pretty good. I have seen new conductors destroyed by loads, etc...


I like the part of trying to be around for that 180 year old conductor.:cool::D
 
kingpb

kingpb

Senior Member
Location
SE USA as far as you can go
Occupation
Engineer, Registered
If all goes well, the original design life was probably estimated at 40 years. However, due to manufacturing impurities, that were not well understood at the time, it is likely that may not last even that long.

There is a process of cable rejuvenation that can be used on certain types of cables.

Worth noting, from a safety standpoint, is that cable manufacturered, I beleive up through the mid-70's was made with asbestos in the insulation. Care needs to be taken when working with this old cable.
 
Status
Not open for further replies.
Top