Archive for category: Electrical Safety

250.52 (A(3) Concrete-Encased Electrode

Categories: Electrical Safety

This weeks column is not about a Code change it is about a common problem we all face on a regular basis.  Footer steel, when is it required to be made part of the Grounding Electrode System?  We will have to check with the building plans examiner or the building inspector and see if there is going to be steel in the footer and if it will need to be made into a Grounding Electrode?

What will require it to be made into a concrete-encased electrode.  There are three requirements to make a good concrete–encased electrode.  The first is that the rod be at least 20’ in length, and it does not have to be one 20’ piece, it can be several shorter pieces connected together to make a 20’ piece.  The second is that it has to be at least a 1/2” in diameter. and the third and probably the most important is that it cannot be isolated from the Earth by a vapor barrier.

We are creating another electrode for our Grounding System.  In section 250.50 they talk about the Electrode being present.  What do we do when it is already poured. I get calls all the time about what to do when they miss the steel in the footer.  At that point I feel that the steel is not available and although you may want to chip into a footer to find a piece of steel rebar how do you know if it is 20’ long, and is not above a vapor barrier?  I have spent time trying to come up with a solution, because chipping into a slab is probably not the best answer. You could cause cracks in the concrete by hitting and vibrating the steel rebar when chipping into the footer.  So when someone calls me in the future and they ask what to do, my solution will be to get them to dig a trench and lay a 20’ piece of 1/2” rebar and make a connection to it and then encase it in at least 2” on concrete.  Maybe next time they will remember to connect the steel and call for an inspection. 

We just need to train the General Contractors and the Electrical Contractors that if this steel if available it is required to be part of our Grounding Electrode System.  If the building plans don’t call for steel in the footer we cannot make them put it in.  It is only required when there is steel and the footer has no vapor barrier and is called out for on the  plans.

 

GESa GESb

Till next time be safe and work safe

 

Jake

PHOTO OF THE WEEK

Categories: Electrical Safety

This weeks photo comes from Mike Dinorscio in Boca Raton.  Thanks Mike

 

Wrong phase

And you wonder why we have inspectors!

 

Got a great photo send it to me at jleccemail@hotmail.com

Jake

Service Conductors and Feeders

Categories: Electrical Safety

This weeks information is not a Code Change but a clarification.  When can Service Conductors be mixed with Feeders? The answer is NEVER!!

 

230.7a

230.7b 

 

Till next week work safe be safe

 

Jake

TERMINATIONS OF CONDUCTORS 110.14

Categories: Electrical Safety

I get a lot of questions on how Table 310.16 work with the three temperature columns, and the terminations of these conductors.  Square D – Schneider Electric has a technical guide to how these sections are applied to the terminations of conductors. See the attached link for information on this very often misunderstood section of the Code.  Jim Pauley the author has been a great asset to the electrical industry for over 25 years.  He often takes on the most controversial sections of the Code and explains them in a way that even a novice in our trade would understand.

Till next time work safe, be safe.

http://static.schneider-electric.us/docs/Power%20Management/0110DB9901.pdf

Send in your questions , we will find an answer.

Jake

Working Clearances

Categories: Electrical Safety

Although this is not a code change it is very important to understand the requirements of this section.

I know we where looking at the one of most violated section of the code 110.26 Spaces About Electrical Equipment several months back and I would like to continue on with that section and examine the safety factors built into these minimums.  There are several clearances that come into play when placing equipment for an electrical installation.  The first is the obvious one of being able to walk up to a panel or some other piece of equipment and service or examine it.  Directly in front of a panel is a minimum of 3’.  That 3’ is the absolute minimum and nothing less, this gives you a quick escape incase something happens and it blows up or shorts out , that 3’ gives you a chance to escape.  I don’t know how equipment can be left with any measurement less than 3’ because it is your life and safety that is the reason for this requirement.  The crews that I work with have come to understand the minimum working clearance in front of equipment, and how important it is, and the reasons behind the requirements of the code.  So over the next couple of weeks and months I will try to examine the clearances and what the minimums are, and why they are so important. 

One of the best teaching tools I have found in the last ten years is my camera and the pictures it takes in order to document our quest for a safer electrical installation. Showing you what I find and how to correct it, is better understood than telling you that you violated a section of the Code. 

IMG_4832pics2-2011violations and pool connectors 022IMG_4731

 

I know it has been a while since I have posted anything but my transition back into the private sector has take more time than I thought it would, so I hope to be back on track now that I have settled in to my new job.

  Till the next time, work safe, be safe

 

Jake

Former Chief Electrical Inspector WPB

How to calculate Auxiliary Gutter fill 366.22(A),(B)

Categories: Electrical Safety

 

Sizing a gutter for the proper fit is relatively easy.  I get a lot of calls to make sure that the gutter that they are using is up to code. 

We are allowed by code to fill a gutter to 20%. of its interior cross-sectional area (366.22(A),(B))  This is for both sheet metal and Nonmetallic gutters

Figuring the 20% is easy, for example.

If you have a 6 X 6 gutter, that would have total of 36 sq. in. and 20% of that is 7.2 sq. in. (36  X  20%  =  7.2 sq. in.) of space to use.  Table

5 is used for the area per conductor.  Take a 3/0 THWN conductor it is listed at .2679 sq. in.for each.  if you wanted to know how many could be

used in a 6  X  6 gutter, you can take the 7.2 sq. in. and   divide it by .2679 to get the maximum number that would be allowed to be installed in

that gutter.  7.2  /  .2679  =  26 conductors. 

You would also have to check the wire bending space minimum from Table 312.6(A). which would require a minimum of 4’” for a 3/0 conductor.

 

Till next time, work safe always check the circuit with a tester.