×
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!
  • Students Click Here

*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

Jobs

Lightning damage Insulation resistance test

Lightning damage Insulation resistance test

Lightning damage Insulation resistance test

(OP)
For making a spot IR test (good/not good) on circuits in a residence, wouldn't it be OK for the general purpose circuits to disconnect the lighting fixtures and leave the wall outlets (with no load) and closed light switches in place? If this combination did not test above about 1 megohm, then the outlets and the switches would need to be pulled and each cable run tested separately. Thanks

RE: Lightning damage Insulation resistance test

I'm unclear as to what you're trying to do.  Getting to a zero-load condition on each and every circuit in a house is non-trivial.  I've got something like 20 circuits, and many of them have built-ins wired to them, and others have possibly unknown or unaccounted for loads.

TTFN

FAQ731-376: Eng-Tips.com Forum Policies

RE: Lightning damage Insulation resistance test

(OP)
Yes, I know getting to zero load on some circuits could be an issue. I want to make insulation resistance measurements using a megohmmeter on those circuits that I am confident in getting to zero load, which will be almost all of them. My question is, can I meg thru outlets and light switches or must I isolate them too.

RE: Lightning damage Insulation resistance test

Obviously, disconnect from the power source. Beware illuminated switches with the built-in neon bulbs. Remove any dimmers or fancy programmable switches. Consider 3-way switches (test twice or more). If you're using a hi-pot type tester, keep the voltage reasonable (600 peak?). Note, I'm not familiar with the applicable regulations (if any). But it seems to make sense that entire circuits could be tested at once.

Years ago, we had a nearby lightning strike. It tripped the main 200A breaker. After the storm passed, I reapplied main power and found one 15A circuit breaker tripped. When I turned that back on, there was a flash and puff of smoke from the outlet box. Called the Fire Dept to make sure there wasn't any fire. Later found that the insulation was damaged where the cable entered the box.



 

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!


Resources