Forums
New posts
Search forums
What's new
New posts
New media
New media comments
Latest activity
Media
New media
New comments
Search media
Members
Current visitors
Log in
Register
What's new
Search
Search
Search titles only
By:
New posts
Search forums
Menu
Log in
Register
Install the app
Install
Main Forums
Do-It-Yourself (DIY) Question & Answer Forum
RCD earth potential
JavaScript is disabled. For a better experience, please enable JavaScript in your browser before proceeding.
You are using an out of date browser. It may not display this or other websites correctly.
You should upgrade or use an
alternative browser
.
Reply to thread
Help Support Talk Electrician Forum:
This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.
Message
<blockquote data-quote="Stringy75" data-source="post: 435890" data-attributes="member: 28416"><p>Has anyone ever encountered a fault with a RCD which causes a potential on earth in respect to neutral?</p><p></p><p>I am a trainee electrician, working with an experienced electrician. We encountered a fault today, earth had a potential of 238V in respect to Neutral and a 0 V potential in respect to line.</p><p></p><p>We did an insulation resistance test at 500V on all circuits from line to neutral, line to earth and neutral to earth. All circuits gave a resistance of &gt;999M ohm. So there is no way line and earth can be crossed anywhere.</p><p></p><p>The fault didn't trip the RCD or the MCB, yet there was a potential difference between neutral and earth.</p><p></p><p>We got really strange voltage readings while probing around, differences between earth and neutral ranging from 100v to over 300v, how can this be as nominal voltage was 238V.</p><p></p><p>The potential difference between neutral and earth was greater when the RCD was in the closed position.</p><p></p><p>All I can possibly think of is the somehow the line windings around the iron core in the RCD have made contact with the Neutral windings. Could a fault like this possibly create a voltage on Neutral, and cos it is a TN-C-S system, Neutral is connected to earth at the incoming supply, so is it possible this voltage could be seen on the earth bar in the consumer unit?</p></blockquote><p></p>
[QUOTE="Stringy75, post: 435890, member: 28416"] Has anyone ever encountered a fault with a RCD which causes a potential on earth in respect to neutral? I am a trainee electrician, working with an experienced electrician. We encountered a fault today, earth had a potential of 238V in respect to Neutral and a 0 V potential in respect to line. We did an insulation resistance test at 500V on all circuits from line to neutral, line to earth and neutral to earth. All circuits gave a resistance of >999M ohm. So there is no way line and earth can be crossed anywhere. The fault didn't trip the RCD or the MCB, yet there was a potential difference between neutral and earth. We got really strange voltage readings while probing around, differences between earth and neutral ranging from 100v to over 300v, how can this be as nominal voltage was 238V. The potential difference between neutral and earth was greater when the RCD was in the closed position. All I can possibly think of is the somehow the line windings around the iron core in the RCD have made contact with the Neutral windings. Could a fault like this possibly create a voltage on Neutral, and cos it is a TN-C-S system, Neutral is connected to earth at the incoming supply, so is it possible this voltage could be seen on the earth bar in the consumer unit? [/QUOTE]
Insert quotes…
Verification
Post reply
Main Forums
Do-It-Yourself (DIY) Question & Answer Forum
RCD earth potential
Top