National Electrical Installation Standards

Standards as High as Your Own

Monday, February 25, 2019


Re: CQD answer published Friday, February 1, 2019 -Vehicle Showroom Classification

1) Good morning, I have run into this before. (And, no, it didn't hurt!)  The issue is, the Class I, Div. 2 area in the shop area extends into the showroom when there are doorways between the two spaces unless efforts are made to prevent this. Positive-pressure ventilation is one method I have seen used. The repair shop area can also be declassified in accordance with Table 511.3(C). Placing the showroom receptacle outlets above 18" is an easy fix.  If they need floor receptacles, one of the other methods would be necessary. However, if there are no openings in the demising wall between shop and showroom, there is no problem. Thanks for the forum! Grant Hammett

2) Receptacles 18" or more above floor, Thursday's question Jan:31:2019. The code section that you are looking for would be NFPA 101 Life & Safety - Ignition point. This would Not be a first here in town. 18" is the height that gasoline fumes rise to before being to heavy to fall back on itself. We have all seen switches spark or receptacles spark (when you yank a cord out especially if something is running at the time). This is an ignition/flash point. Whether it is a garage at home, repair garage, parking garage or in this case, a showroom - anywhere there could be gasoline fumes, the standard receptacle height would not be acceptable and must be over 18" off the floor. Many times, I have had an electrician tell me, "If it is not in the NEC, I am not doing it." As an inspector, we have to enforce all codes (and there are so many) no matter where it appears and will not sign off until compliance is met. As far as NFPA 70, where is the location for smokes & CO's (new and existing buildings)? The building code. Where is stair illumination (interior and exterior)? The building code. We also need to look at other areas of the NFPA, gas code (bonding), NFPA 1 & 101. Most of the time here, I see garage receptacles at three or four feet (convenience outlets) and yes, floor outlets would be a no no. I find electricity gets a bad wrap when it comes to fires, It is too easy to say it was an electrical fire. But shame on us should there be a fire and a Fire Marshal sees those receps are within the 18" range. Many times I have purchased a new vehicle and seen the staining on the ground when raining. New vehicles can leak (and stink). I would support the inspector in this case, he seems well read.Thank you for this treat every morning. Great job though I miss Charlie. Big Bad Busy Bob (or so I was called by a resident in a PB meeting)



Hey Grant and Bob, thanks for your comments and the kind words. NFPA 30A, Code for Motor Fuel Dispensing Facilities and Repair Garages has some additional rules. Table 8.3.2...areas adjacent to classified locations are generally unclassified - if they have specific amounts of positive ventilation or air changes: or if they are effectively cutoff by walls or partitions. 8.3.3 Classified areas often do not extend beyond floors, walls, roofs or other solid partitions that has no openings.

If there are openings, such as doors, between the vehicle repair area and showroom and the conditions stated are not met the classified area could extend into the showroom.

NFPA 101 refers to the NEC (NFPA 70) in 9.1.2 but the term Ignition Point is not used that I am aware of. If you have a specific reference please send it in. Auto Ignition temperature and Flash Point are used in the NEC and are defined in other NFPA Standards such as NFPA 497. The term Ignition Source is used in Building Codes and includes switching devices.

The original question indicated that the submitter had extensive experience designing vehicle show rooms and this was the first time they were asked to meet the 18 inch dimension. It seems the rules are not consistently enforced or used.

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IMPORTANT NOTICE: All answers are based on the latest edition of the National Electrical Code®, unless the question requests a response based on a specific edition. This correspondence is not a formal interpretation of the NEC®. Any responses expressed to the questions are opinions and do not necessarily represent the official position of NECA, NFPA, or any technical committee. In addition, this correspondence is neither intended, nor should it be relied upon, to provide professional consultation or services.

ABOUT CHARLIE: Charles M. Trout, better known as Charlie, was a nationally known NEC® expert and author. He served on several NEC® technical committees and is past chairman of CMP-12. In 2006 Charlie was awarded the prestigious Coggeshall Award for outstanding contributions to the electrical contracting industry, codes and standards development, and technical training. Charlie was also a member of NECA’s Academy of Electrical Contracting. Charlie’s experienced team of industry experts keep the CQD dialogue and discussions active and informative in the spirit of the man himself, as he wanted.

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