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GFCI vs GFEP vs AFCI

August 12, 2011 By Leave a Comment

Ground Fault Circuit Interrupter (GFCI) is a safety device which is intended to interupt the circuit that it is protecting quickly and under very small currents to ground.  The intent is to ensure that there is no chance of shock or electrocution from a fault to ground.  UL and CSA specify that the circuit must interrupt between 4 and 6 mA

Ground Fault Equipment Protector (GFEP) is a equipment protective device.  They work on the same principle as a GFCI but are typically set at 30mA.  They are used with outdoor installations such as ice melting, heat trace, etc

Arc Fault Circuit Interrupter (AFCI) is the new kid on the block.  A AFCI is newly required by the NEC and CEC in all bedroom circuits, they are designed to trip on a arc signature.  These types of faults have been found at the cause of many residential fires.  By including this type of protection on circuits in the home the electrical source will be cleared before a fire has a chance to start.  There is talk that they will be required on all residental circuits by the 2012 code.  NEMA has a great website for AFCI's called AFCIsafety.org

Both the NEC and CEC have requirements where each type of ground fault interrupter must be used, however this does not include ground fault protection on grounded wye systems.

If you would like to know more about this topic, or have a question please leave a comment or take advantage of the contact page.

Filed Under: Definitions Tagged With: , ,

What I’m Reading: Week 1 (Reboot)

February 5, 2011 By Leave a Comment
  • Support AFCI Safety - The 2011 NEC requires the installation of Arc Fault Circuit Interruptors in new residential construction.  Check out the campaign to raise awareness on Facebook.
  • Power supply for temporary installations within the entertainment industry has always interested me.  Then I started reading the EESCO website and they post a lot of great links and articles on safety and code.  Including the disconnect requirements at tap points.
  • Another EESCO article that I came across was the CSA Z462 Fact Sheet published last year.  It is still relevant today, if you are unsure about what CSA Z462 is, this article is a good place to start.
  • Match the motor to the load - Plant Services has a great article about why matching motors to specific loads will increase overall plant reliability.
Filed Under: What I'm Reading Tagged With: , , , ,

Incident Energy Report – What you need to know

December 9, 2009 By Leave a Comment

Wow, that was bad.

Near the end of October I was shown a very poorly written Incident Energy Report.  The reason that it was given to us, a competing consulting firm, was that we designed the system and on of the action items listed was regarding the size of the transformer protection.  They said it was wrong, we checked and they were wrong.

For the record, the secondary circuit breaker of a transformer may be used for the transformer protection as long as it is no greater than 250% of the full load current of the transformer AND the up stream protection from the transformer is no greater than 600% that of the full load of the transformer.

We checked and we meet both of these requirements. Besides that, the breaker settings that we used, and they used in there report, were well within the transformer damage curves.

What’s this all about?

But that is NOT the reason I am writing this first entry, basically there are some things that every Incident Energy Report must include. Since this is more than can be covered in a single post I am going to write a 6 Part series explaining what I believe must be included in every IE Report.

The parts are:

  • Part 1: Site Background Information and Scope
  • Part 2: Description of the System
  • Part 3: Short Circuit Information
  • Part 4: Protection Coordination Information
  • Part 5: Incident Energy Levels and associated Boundaries
  • Part 6: Recommendations

Each one of these sections must be included in every report that you may write or receive from a consultant.  If one is missing when a review report is issued ask why it is missing.

This is not to say that each section will have to be called out within the report, depending on the scope and size of the system they may be simply broken out into line items, but they must be included.  However in this one report that I had viewed, this was not the case, and this is why I have decided to write this series of posts.  I will be adding the posts through the months of January and February and will have a detailed summary post at the end.

Filed Under: Featured Tagged With: , , , , , , , ,

High Fault Contribution may not be a bad thing

October 26, 2009 By 2 Comments

In the past you determined the bus withstand of equipment by the bolted fault.  In some cases the system would be designed to limit the available fault energy on any one bus by installing higher impedance transformers, multiple small transformers, etc.

Today there is as much concern regarding the Incident Energy (IE) released in an arc fault as there is regarding if the equipment can withstand a bolted fault.  In regards to IE more fault current may actually lower the energy when the protection is in its instantaneous range.  The amount of time required to clear a fault decreases as the magnitude of fault current increases. The IE equation, energy is related to the square of time. If the time to clear the fault is halfed, the IE is 25% of the original.

Higher fault energy typically represents a stiffer overall electrical system.  This leads to better coordination as the designer will be better able to predict what will happen during an incident.

Filed Under: Arc Flash, Electrical Safety Tagged With: , ,

What I am reading – Week 1

June 12, 2009 By Leave a Comment

Friday is a great time to post some of the stories that I have been reading this week.

  • Copper thefts threaten infrastructure - This is something that happens more and more frequently whenever the price of copper increases.  I did notice that there were a lot fewer stories inthe local news regarding this type of theft when the price of copper dropped, but I expect it will be picking up again soon.
  • Power lost in the Tenderloin - Well this story is actually about power being restored, but it seems that there was a blast in one of the underground vaults in the Tenderloin Area of San Francisco.  It piqued my interest when I was scanning Google News since last time I was in San Francisco (my first trip there) we stayed 2 blocks from this area.  It is by far the sketchiest place that I have ever been.
  • Relationship between CEC and CSA Z462 - I found this in my Google Alerts, anything related to the recent release of CSA Z462 is interesting to me.  I am particularly interested in how industry is deciding to implement it.
  • Devices to enable better control of Renewable Energy Sources - This is one of the things that I feel most people are over looking with their rush to put more renewable sources on the grid.  The North American electrical grid was not designed with these type of intermitent energy sources in mind.  The simple fact that you can't reliably predict when the wind is going to blow, or if it is going to be cloudy is a major factor regarding the stabilization of the grid during heavy load.

If you have a link that is interesting please post it in the comments.  I have a wide range of interests when it comes to the Electrical Energy field, and safety in general.  If you have a link to a particular Arc Flash or other safety incident I am particularly interested in reading about it.

Filed Under: What I'm Reading Tagged With: , , , , ,
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