12/29/2023 0 Comments Calculate the service demand locad![]() "If I have a demand load (lets say for lighting) of 125% I calculate my demand and then I go ahead and multiply that total by the demand of 125%." Have you multiplied by 125% once here, or twice? Sounds like twice already. Here in Chicago, the local code does require 125% demand factor for lighting, but I think that has much more to do with unions than science - I can't think of any rational explanation for how the measured demand would exceed the connected load, and I'd never heard of a demand factor over 100% before I moved here. NEC, in Table 220.11, in no case lists any lighting demand factor over 100%. Your post leaves me with a couple questions, though:ġ. That's because the service entrance will see the average power to the whole facility, and generally will not be so affected by localized peaks in demand here or there - in other words, when power is peaking way over on the west side, it's most likely NOT peaking way over on the east side. Usually, that demand factor would tend to get smaller as you go on up the chain towards the service entrance. Then, there will be a demand factor that applies to each level of the distribution system. They all add directly such that your service entrance has a connected load equal to the total of the connected loads on all the branch circuits it eventually feeds. Think of it this way: calculate connected load. UPDATE YOUR SUBSCRIPTION PREFERENCES: Subscribe or Unsubscribe from this list.In general, the answer is no, you don't multiply demand factors against each other. In addition, this correspondence is neither intended, nor should it be relied upon, to provide professional consultation or services. This correspondence is not a formal interpretation of the NEC® and any responses expressed to the questions are opinions and do not necessarily represent the official position of NECA, NFPA, the NEC Correlating Committee any Code-making panel or other electrical technical committee. IMPORTANT NOTICE: Unless the question requests a response based on a specific edition, all answers are based on the latest edition of NFPA 70® National Electrical Code®. View a full listing of available resources and products » NECA SAFETY PRODUCTS & PUBLICATIONS: NECA produces electrical safety publications and products for the industry including jobsite safety guides, handbooks and resource kits. NEIS can be purchased in the NECA Store in three formats: a printed or PDF download of a standard or, as an annual subscription service. NECA STANDARDS: NECA publishes the National Electrical Installation Standards™ (NEIS™), a series of ANSI-approved performance and quality standards for electrical construction. NECA continues to maintain this question forum for its many subscribers in memory and recognition of all his significant contributions to making the NEC what it is today. Even though Charlie passed away in October of 2015, his work continues in spirit. In 2006 Charlie was awarded the prestigious Coggeshall Award for outstanding contributions to the electrical contracting industry, codes and standards development, and technical training. He served on several NEC® technical committees and is past chairman of CMP-12. Trout, better known as Charlie, was a nationally known NEC® expert and author. SUBMIT YOUR CODE QUESTION: Click here to submit a question to for inclusion in an upcoming edition of the Code Question of the Day, or email TROUT: Charles M. The daily distribution of Q&A generates a lively dialogue and shares relative Code-based practical responses. The garages would be 4 separate 12 unit buildings, one service panel and separate feeder panels at the other 3 buildings.ĪBOUT CQD: The Code Question of the Day (CQD) is NECA and ELECTRICAL CONTRACTOR Magazine’s flagship National Electrical Code (NEC®) public forum for the industry, sponsored by EATON. Do we calculate these loads as non-dwelling and use 180 VA for each receptacle, 100 VA for each light and calculate the openers as a multi motor load according to 430.24? When I do that calculation I came up with a connected load of 292 amps, are there any demand factors that can be applied to this number? Since these garages are associated with a dwelling unit, do we use 220.12 and not include the lights and receptacles since they are not included in the 3 VA per square foot calculation for dwelling units, this brings us down to 236 amps but still is quite large for what in reality is a very small actual demand. For an example: we have 48 garages, with a ½ HP 120 volt door opener, a light with a 100 watt bulb, and a 120 volt GFCI receptacle in each garage. We have been having a discussion about how to calculate the load and size the feeders or a service for the detached garages of an apartment complex, and are hoping you could shed some light for us on the appropriate method and if there are any demand factors that can be applied.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |