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Utility Transformer FAQs

1.  What counts as alternate methods and means to allow us to use the 3' minimum clearance?

Alternate methods and means is a process where registered design professionals submit a detailed substitute for the code requirement that will assure equivalent protection or performance, when the code standard can not be practicably applied.  The FM Global Data sheet shows a 3' clearance allowed with FR3 fluid filled transformers.

2.  What is the charge associated with the FR3 fluid?

The Utility company needs to be contacted for a concise answer.  In our brown bag meeting one Utility stated the raw costs increase is about 15%.

3.  Can you provide clarification that the replacement/maintenance of an existing transformer will not put a structure in violation.  Under what circumstance is an existing structure subject to this new interpretation?

Existing transformers that are replaced by the Utility without any owner improvements will not be evaluated by Code Enforcement, but may need to adjust per Utility requirements.  If changes are made to the owner's system the current Code Enforcement policy will need to be complied with.  Additionally new transformers may affect adjacent buildings and their installation will need to comply with the policy.

4.  Does habitable or non habitable make a difference?

No, the protection is for the building as well as the occupants.

5.  Can you define combustible and non combustible?

These terms are defined in the NC State Building Code and by compliance with recognized standards.  Chapters 6 & 7 are applied to obtain the ratings.

6.  What are the garage door requirements or applications?

Doors are addressed in the Duke Standard.  All "wall openings", fire escapes, fire exits, windows, doors, and vents are addressed with dedicated clearances.  Per 450.27 of the NEC; Combustible material, combustible buildings, and parts of buildings, fire escapes, and door and window openings shall be safeguarded from fires originating in oil-insulated transformers installed on roofs, attached to or adjacent to a building or combustible material.

7.  Who will enforce the standard and when will it come in play?

Currently the Duke Standard has been agreed to by four of the five area Utilities and as an acceptable method of compliance per Code Enforcement.  Hopefully the remaining Utility will agree as well in the near future.  The Duke Standard is currently in play for all new installations since January 1st this year.  Code Enforcement will evaluate all on a case by case basis per our direction from the NC Department of Insurance and the NEC.

8.  Are there differences in commercial or residential applications?

Both are addressed by NEC and the Duke Standard.  Each installation will be considered individually as the installations are not all the same.

9.  Who is the governing body over the Utilities?

Utilities differ in structure and regulation.  Please call your utility provider for precise information.

10.  Why are projects that are already permitted not grandfathered under previous guidelines?

The permitted projects prior to January 1st will be evaluated on a case by case basis.  Only those that pose imminent danger will need to be addressed.

11.  Does secondary egresses meet the requirement for safe passage?

All required egress means are to be protected per the Duke Standard and the NEC.

12.  What event precipitated the need for the change, an amendment to National Electrical Code, National Fire Codes and/or NC Building Codes; a federal mandate; a directive from Duke Energy; or was it a terrible accident that illustrated why the change is needed? 

The process arose from our questions of how the utilities were addressing building and occupant protections from the hazards that may arise from placement of oil filled transformers inside and outside of buildings.  The NEC and the NC State Electrical Code in Article 450.27 lists methods by which protections can be achieved.  Code Enforcement began seeing several installations that appeared to be questionable with regards to safety of potential electrical arc faults, explosion and fires.  The utilities seemed to have somewhat differing guidelines and the National Electrical Safety Code addresses the issue in Section 15, 152. A. 2 much the same as the NC State Electrical Code.  We were aware that the General Statutes excluded us from authority over the utility equipment.  We contacted NCDOI/OSFM for clarification of how we needed to address our concerns.  We were informed that while we indeed had no authority over the utility equipment we still had to protect the buildings and occupants from the imposed dangers.

13.  Do we have a choice of accepting the change (or not), or is this a mandate from some authority?

We are to enforce the code as adopted by the State of NC and as stated above the NCDOI/OSFM directed us to protect the buildings and occupants.  By NC Statute they are responsible for our general supervision.

14. Does the change apply just to Charlotte, Charlotte-Mecklenburg, the State, or the Nation?  The more local the rules, the less competitive Charlotte becomes for housing prices, commercial service space, offices for jobs, and industrial buildings for jobs and investment.

The Codes apply where ever they are adopted and in NC they are to be enforced statewide.  Additionally utilities have standards that they enforce.

15.  What is the goal of the change?  Said another way, what exactly are we trying to accomplish with the added distances (<12' from a combustible structure (measured from the overhang) 20' from doors, 10' from windows) that is not currently adequate?  It sounds like there is a lot of dialogue on alternative methods to meet the ruling, and the hope is that they are cost neutral. 

The goal is to protect the buildings and occupants with reasonable and practical engineering practice and recognized industry standards, in recognition of the imposed hazards.

16.  Did the issuing authority and the Code Enforcement office perform any cost studies on residential, office, industrial and commercial applications to determine the impact to new development?

The enforcement policy resulted from existing codes and standards, and as previously stated was an effort to conform to reasonable compliance with them.  Not being a new code change the cost study associated with NC State Code changes was not done.

17.  Most of these questions are in response to a rising swell of regulation that is enveloping the (re)development industry in a cross-fire of rising costs and decreasing building envelopes (area of a site that we can put rentable SF on – vs. transformer containment pads, undisturbed buffers, 7' wide sidewalks and the like).  If the trend continues, the result will be a permanent reduction in permit revenues because fewer projects will be economically feasible – even after economic strength returns. 

While not intended as a negative force, the reality of safety standards inevitably will contribute to costs factors.  We are trying as much as possible to inform all parties of the situation and dangers, and to have everyone understand that it is a total industry concern that must be addressed in partnership with all involved.  At this time we are informed that a standard will be presented for adoption to the NC State Code, in an effort to harmonize standards and enforcement.


•  For general permit information, please call 704-336-3830

•  For general electrical code questions, please call CTAC 704-432-4668

•  For Code Interpretations, please call Joe Weathers,  Electrical Code Administrator,  704-336-5379

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