Motel / Hotel electric heat calc - Electrician Talk - Professional Electrical Contractors Forum
Go Back   Electrician Talk - Professional Electrical Contractors Forum > Electrical Trade Topics > NEC Code Forum

View Poll Results: How well educated is your AHJ with the NEC?
Excellant 2 33.33%
Good 2 33.33%
Poor 1 16.67%
Terrible 1 16.67%
Voters: 6. You may not vote on this poll

Thread Tools Display Modes
Old 02-27-2007, 11:15 AM   #1
Junior Member
Join Date: Feb 2007
Posts: 10
Rewards Points: 10
Question Motel / Hotel electric heat calc

I have a hotel I'm bidding on with 60 rooms, each room has a FLA wall heater of 25 amps 240 volt (single phase). I figured 6000VA for each unit
6000VA x 60 units = 360,000VA

I= VA / E 360,000 / 240 = 1500 amps
1500 amps towards the total service calc from heat (larger load than the AC)
I beleive this 1500 amps would be at 100%, but in the NEC 250.51 has an exception that gives the local AHJ authority to change the %.

How can the AHJ even think that all 60 rooms in the middle of winter couldn't be sold out and all using there heat.

Has anyone ran across this before??
jd77 is offline   Reply With Quote
Join Contractor Talk

Join the #1 Electrician Forum Today - It's Totally Free! - Are you a Professional Electrical Contractor? If so we invite you to join our community and see what it has to offer. Our site is specifically designed for you and it's the leading place for electricians to meet online. No homeowners asking DIY questions. Just fellow tradesmen who enjoy talking about their business, their trade, and anything else that comes up. No matter what your specialty is you'll find that is a great community to join. Best of all it's totally free!

Join - Click Here JOIN FOR FREE

Warning: The topics covered on this site include activities in which there exists the potential for serious injury or death. DOES NOT guarantee the accuracy or completeness of any information contained on this site. Always use proper safety precaution and reference reliable outside sources before attempting any construction or remodeling task!

Sponsored Links
Old 02-27-2007, 05:53 PM   #2
Wire Ninja
MDShunk's Avatar
Join Date: Jan 2007
Location: Beautiful Cumberland Valley, in PA
Posts: 18,249
Rewards Points: 3,855

I will only calculate the heat at less than 100% if I've personally done a ACCA Manual 'J' calculation such that I know the heat is oversized. If the heat is oversized by a certain percentage, then I'd go less than 100% by approximately an equivalent amount to the oversizing.

The only two motel jobs I've been involved with were engineered, so no calculations were involved on my part. A PTAC with resistance heat is the typical motel heat and A/C source. They don't come in too many different sizes, so yours may be oversized slightly because of that. Hard to say.
MDShunk is offline   Reply With Quote
Old 02-28-2007, 03:02 PM   #3
Senior Member
frank's Avatar
Join Date: Feb 2007
Location: Saxon Village near Doncaster. Buildings date to 8th century.Once a Roman Road
Posts: 1,313


The arithmetic rule you are querying is called 'diversity'. A safe rule of thumb is to apply 25% diversity to your maximum demand rule. So if you calculate a max demand of 100kVa then supply distribution protection etc to fail at 75kVa. This difference is based upon the chance rule of occupation and opperation of themostats etc switching on and off the load etc. It is a good safe rule and used by engineers everywhere. Just think about your household electric cooker. If you cabled etc to allow for all plates to be on all day you would really have to overwire and protect. Local/National regulations may apply to your calculations so go with these but you would be safe to apply 'diversity' and so save some installation costs.

Frank Doncaster England
frank is offline   Reply With Quote

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Similar Threads
Thread Thread Starter Forum Replies Last Post
cable calc software cheekivimto06 General Electrical Discussion 0 11-11-2008 12:46 AM
dwelling calc. rknrll813 General Electrical Discussion 0 10-07-2008 08:50 PM
load calc. rknrll813 General Electrical Discussion 1 08-14-2008 07:27 PM
Load Calc. for Old Single Family Dwellings Reseman Services and Service Equipment 5 05-31-2008 09:21 AM
heat calc. rll77 Services and Service Equipment 16 03-29-2008 05:58 PM

All times are GMT -4. The time now is 04:01 AM.

Powered by vBulletin® Version 3.8.8
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.1
vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
User Alert System provided by Advanced User Tagging (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Our Pro Sites Network | | | | |