Code Change of the Week

700.3(F) Temporary Source of Power for Maintenance or Repair of the Alternate Source of Power.

A new section was added to 700 section 700.3(F).  If you have a required emergency generator system, and you have to take it out of service for repairs or maintenance you have to have temporary or portable means to maintain the emergency backup system. There are many ways to achieve this backup to the backup system, a Kirk key systems and Cam locks systems are some of the means to achieve this backup, but that will be up  to the design professional.  In the 2017 when designing a system you will be required to meet the Code requirements from 700.3(F) for the emergency backup system..

700.3(F) Temporary Source of Power for Maintenance or Repair of the Alternate Source of Power.

If the emergency system relies on a single alternate source of power, which will be disabled for maintenance or repair, the emergency system shall include permanent switching means to connect a portable or temporary alternate source of power, which shall be available for the duration of the maintenance or repair. The permanent switching means to connect a portable or temporary alternate source of power shall comply with the following:

(1)Connection to the portable or temporary alternate source of power shall not require modification of the permanent system wiring.

(2)Transfer of power between the normal power source and the emergency power source shall be in accordance with 700.12.

(3)The connection point for the portable or temporary alternate source shall be marked with the phase rotation and system bonding requirements.

(4)Mechanical or electrical interlocking shall prevent inadvertent interconnection of power sources.

(5)The switching means shall include a contact point that shall annunciate at a location remote from the generator or at another facility monitoring system to indicate that the permanent emergency source is disconnected from the emergency system.

It shall be permissible to utilize manual switching to switch from the permanent source of power to the portable or temporary alternate source of power and to utilize the switching means for connection of a load bank.

Informational Note: There are many possible methods to achieve the requirements of 700.3(F). See Figure 700.3(F) for one example.

Exception: The permanent switching means to connect a portable or temporary alternate source of power, for the duration of the maintenance or repair, shall not be required where any of the following conditions exists:

(1) All processes that rely on the emergency system source are capable of being disabled during maintenance or repair of the emergency source of power.

(2) The building or structure is unoccupied and fire suppression systems are fully functional and do not require an alternate power source.

(3) Other temporary means can be substituted for the emergency system.

(4) A permanent alternate emergency source, such as, but not limited to, a second on-site standby generator or separate electric utility service connection, capable of supporting the emergency system, exists.

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Till next time be safe work safe

Jake

Continue Reading700.3(F) Temporary Source of Power for Maintenance or Repair of the Alternate Source of Power.

ANNEX D EXAMPLE “7” RESIDENTIAL SERVICE TABLE

Below you will find a picture of Annex D example 7 from the 2017 NEC pages 799/800.  It was put back in the Code to do away with the confusion that was created when they took the table out of the Code book and made it into a calculation.  To many inspectors, plan reviewers, engineers, and architects have been wrongfully applying this section of the Code for a while now.  I get numerous calls and emails about having to use 3/0s for a 200a service when in the past we used 2/0s.  I only use the 200a service as an example.  The Code panelists never meant to make it so difficult to figure out what they wanted, but unfortunately they did.  When they made it a calculation they did not change the sizes of the wires in the table they just made it into a calculation, that for some reason we’ve had a tuff time understanding.  As long as the load calculation does not exceed 200a the 2/0s are the conductors needed to feed a 200a service. This method works for all services of a100a on up to and including a 400a service   So in the 2017 NEC they placed the residential table back in the Code back in Annex D.  Probably the most misunderstood part of this Code section is that the conductors being used will have a load calculation that is above the ampacity of the conductor involved. Maybe the Code panel should include this section with the other conductor applications listed in 240.4(G).

If you have any comments or questions about this change please email me at jleccemail@hotmail.com

Can’t see the whole slide just click on it.

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Till next time be safe work safe.

Jake

Continue ReadingANNEX D EXAMPLE “7” RESIDENTIAL SERVICE TABLE

404.22 Electronic Lighting Control Switches.

This section gives us a date to stop making connections to an equipment grounding conductor on January 1, 2020, at switch locations that have electronic dimmers or controllers installed.  After that date we need to be using a neutral conductor to make these devices work,  no longer allowing the equipment ground to be used for this purpose.  Although a neutral is not necessary at all switch points section 404.2 C instructs us when and where a neutral is needed. And with all good Code changes there are exceptions,  this does not apply to replacements or retrofits, and has a limit of 5 (five) devices per branch circuit and 25 (twenty five) per feeder connected on the load side in the system or main bonding jumper. A neutral busbar in compliance with 200.2 B has no limits as to the number of electronic devices connected to it.

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Can’t see the whole picture just click on it.

Have a question email me at jleccemail@hotmail.com

Till next time be safe work safe.

Jake

Continue Reading404.22 Electronic Lighting Control Switches.

250.52(B) Not permitted for use as Grounding Electrodes

New to this section the reinforcing steel that forms a swimming pool shell.  A swimming pools’ steel cage is not to be used as part of our grounding electrode system.  I have heard stories where the inspector required that the contractor run the pool bond back to the ground rod?  This practice a “violation” and could endanger the occupants of the pool with stray currents or ground-fault current introduced on this grounding electrode system.

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Can’t see the whole picture then just “Click” on it.

Till next time be safe work safe.

Jake

Continue Reading250.52(B) Not permitted for use as Grounding Electrodes

2017 Code Changes

This week we will start a series of Code Changes found in the 2017 NEC.  Every couple of weeks we will explore one of the changes.  If you have questions please email me at jleccemail@hotmail.com.  REMEMBER THESE ARE NOT IN USE BECAUSE THE FLORIDA BUILDING COMMISION HAS NOT ADOPTED THE 2017 NEC YET!!!!!

The first one we will look at is in Article 110.14(D) Installation (of devices outlets, switches etc., etc..).  This new section requires us to torque all connections that require torqueing which would now include switches and receptacle outlets, or any equipment that has a numerical value on the device or in the instructions provided by the manufacturer.  A couple of manufacturers have come out with devices that come with a snap in tails which would not require torqueing.  See the slides below, if you can not see the entire slide just click on it to make it bigger.  

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But for those who don’t have the snap in tails , you will need a torqueing screw driver.

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Till next time be safe work safe.

Jake

Continue Reading2017 Code Changes

310.15(B)(7) 120/240-Volt, Single-Phase Dwelling Services and Feeders.

I keep getting calls from contractors that tell me that this town or that county no longer allows them to use 2/0 Cu. for a 200a dwelling service or feeder.  This section changed in the 2014 Code but the only thing that changed is they took out the Table and made it into a calculation using 83%.  This 83% rule has seemed to throw off a lot of people in our trade (plan reviewers, inspectors, and contractors).  Just so you know the old table from 2011 Code will still work nothing has changed.  It is not just the 2/0s its all the conductor we use to use in the old Table (see the Table below) they all still work for serving the loads that are shown to serve in the old Table.  They work for both feeders and services.

EXAMPLE:

A 2/0 conductor in the 75 degree column in 310.15(B)(16) is good for 175 amperes

A 200 ampere service rating multiplied by 83% equals a 166 amperes.

So as you can see a 2/0 will be large enough to serve 166 ampere service rating.

                                                                                                                                                                                                                                                                                                                  

As long as your load calculation does not exceed 200 amperes the “CODE” allows you to exceed the rating of the 2/0 conductors ampacity, by applying the 83% rule in 310.15(B)(7)(1)(2).

                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      

See #1 and #2 below to see what the conductors ampacity is based on “SERVICE RATING” and FEEDER RATING”

310.15(B)(7)

(1) For a service rated 100 through 400 A, the service conductors supplying the entire load associated with a one-family dwelling, or the service conductors supplying the entire load associated with an individual dwelling unit in a two-family or multifamily dwelling, shall be permitted to have an ampacity not less than 83 percent of the service rating.

(2) For a feeder rated 100 through 400 A, the feeder conductors supplying the entire load associated with a one-family dwelling, or the feeder conductors supplying the entire load associated with an individual dwelling, unit in a two-family or multifamily dwelling, shall be permitted to have an ampacity not less than 83 percent of the feeder rating.

3/0 is not needed for a dwelling service rated 200 amperes unless it is not feeding the entire load to that dwelling.

Below you will find a dwelling service table from the 2014 Florida Building Code 5th Edition that was taken out in the 6th Edition of the FBC, but it still works and it includes  both copper and aluminum conductors plus the size of the required grounding electrode conductor.  Use it in good faith that it will give you the right size service and/or feeder to your dwelling unit. .

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Till next time be safe work safe

Jake

Continue Reading310.15(B)(7) 120/240-Volt, Single-Phase Dwelling Services and Feeders.

Do I need and outlet at my service?

Question came up this week in reference to having a service outlet near the service equipment.  I referred them to section 210.64 and told them one was required, except at a one-family and two-family dwelling. This would be for service equipment installed both inside or outside of a building.   If you install a 480 volt service make sure to put in a small step down transformer in order to comply with this section………..

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Till next time be safe work safe

Jake

Continue ReadingDo I need and outlet at my service?

New Code change to 240.87 Arc Energy Reduction

First of all for today I hope you all enjoyed the day off to celebrate the annual Labor Day holiday.  You all work so hard an a day off to celebrate that hard work is deserved.

Todays news letter has to do with Arc Flash reduction, which is a requirement of the Code to help reduce an arc flash incident if one was occur when someone was working on a live “Hot” piece of switch gear.  The methods described in the article would allow someone to work on a main switch or disconnect that is hot and set the breaker or by-pass switch to maintenance mode so that if an incident was to occur it would clear almost instantaneously reducing the incidents arc flash. Thereby giving the worker added protection from a possible disastrous arc flash incident. 

This section first introduced in 2011 has been updated in the 2014 giving us some additional ways to reduce the hazard for workers who are working within the Arc Flash Boundary as defined NFPA 70E.  Based on the 2014 guide lines for mitigating the hazards of working on energize switch gear, there are now several ways to limit the time a circuit breaker will  take to shut off reducing the arc flash incident. All of these methods will require you to research the methods to find the one that works for your installation. 

A few contractors have asked about ways to work around this code article, especially ones who are working on high end residential projects.  Homes with 1200 ampere services or larger.  One way would be to have multiple mains smaller than 1200 amperes or use fused disconnects for mains, both which are not covered by this article. 

When designing and building a service this large you would have to have an engineer involved because of Florida statute 471.003 h which only allows an electrical contractor to design and build a residential services up to 600 amperes at 240 volts, and commercial services up to 800 amperes at 240 volts.. So next time you encounter a large service (1200 amperes or larger) commercial or residential maybe you can suggest a couple of smaller mains rather than going with the larger one.   


See the Code section 240.87 below:


240.87 Arc Energy Reduction

Where the highest continuous current trip setting for which  the actual overcurrent device installed in a circuit breaker is rated or can be adjusted is 1200 A or higher, 240.87(A) and (B) shall apply.


(A) Documentation. Documentation shall be available to those authorized to design, install, operate, or inspect the installation as to the location of the circuit breaker(s).
(B) Method to Reduce Clearing Time. One of the following or approved equivalent means shall be provided:


(1) Zone-selective interlocking

(2) Differential relaying

(3) Energy-reducing maintenance switching with local status indicator

(4) Energy-reducing active arc flash mitigation system

(5) An approved equivalent means


All of the ways to minimize an arc flash incident will have to be done under engineering supervision in order to meet one of the five methods required in the above Code section.

Till next time be safe work safe.

Jake

Continue ReadingNew Code change to 240.87 Arc Energy Reduction

Code Change 450.11 (B) Source Marking

Out in the field we do it all the time, we back feed a transformer with 208v and boost it up to 480v to feed a piece of equipment, or to use it to help with voltage drop in a long run, but now the Code has made it a requirement to be done in accordance with the manufacturer’s instructions.  Not all transformers have these instructions.

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Have a question you like answered, email me at jleccemail@hotmail.com

Till next time be safe work safe

Jake

Continue ReadingCode Change 450.11 (B) Source Marking

Required outlet at a Commercial/Industrial service location 210.64

This is a new requirement in the 2014 Code that has already been amended in the 2017 Code.  In the 2014 it requires a 15 or 20 ampere receptacle

to be installed within 50’ of the service area.  Then in the 2017 Code they amended it so that a receptacle will not be required if the voltage of the service

is above 120 volts to ground for services in and around Electrically driven or controlled irrigation machines or near natural or artificial bodies of water in

articles 675 and 682 .

 

2017 NEC 210.64 Exception No. 2: Where the service voltage is greater than 120 volts to ground, a receptacle outlet shall not be required for

services dedicated to equipment covered in Articles 675 and 682.

So in the picture below you would have to add a transformer and panel to feed a 120 volt GFCI protected receptacle unless it is a service for equipment

covered in articles 675, and 682..

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Till next time work safe be safe……

Jake

Continue ReadingRequired outlet at a Commercial/Industrial service location 210.64