×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

cables

cables

(OP)
what is a life long of a pvc/swa/pvc/copper cable , even if it hasn't been connected to a load ?

RE: cables

By not connected to a load, do you mean energized but no load?  If so, the worst condition for a cable is to be energized but have no load (current) through it.  The cable is subjected to voltage stresses without the benefit of heating from the load current.  This will shorten the life.

If the cable has been sitting in conduit or tray, de-energized and you are thinking of energizing it, I would probably do some testing such as a megger.

Cables are affected by environmental factors (especially organic insulations) by water, radiation, sunlight, heat oxidation, etc.  Also the operating environment where the cable is installed can affect the life - salt spray, chemicals, etc.

Hope that helped
wbd

RE: cables

WBD...  What you have said does not make common sense to me, however, I am very trainable.  Please provide more detail on how the life of a cable is extended because of heating caused by load current.  I have never thought of heat as a benefit to the life of a cable.

I do agree with your last two paragraphs.

Wirenut

RE: cables

The heat from the current helps keep out any moisture intrusion into the cable.

RE: cables

geeny,

Perhaps a little flippant, but in the UK, PVC with respect to cables was run over and killed be the wiring regulations (BS7671 2001). PVC cables are now to be known as thermoplastic!

RE: cables

WBD

Thanks for the information.  I have never thought of it that way before now.

Wirenut

RE: cables

I agree with what WBD says regarding the effect load as a prophylaxis against moisture, so I will not repeat any of that.
I think your last question is a request for the expected life of a cable?  

There are a few dependent factors when you are trying to determine life expectancy, and it is far from an exact science.  In fact I wouldn't go so far as to call it a science yet. (I know some statisticians would disagree)

As WBD mentioned, operating environment is a factor, as is the operating voltage and the insulation thickness.
Usually the cable manufacturer can give you some hints based on the application, but usually they shoot for life cycles of about 30 years for what they call "normal" conditions.  (I placed "normal" in quotes becuse the manufacturer needs to define that based on the design of the cable.)
Good luck!

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members! Already a Member? Login



News


Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close