The Electrical Contractor Network

ECN Electrical Forum
Discussion Forums for Electricians, Inspectors and Related Professionals

Books, Tools and Test Equipment for Electrical and Construction Trades

Register Now!

Register Now!

We want your input!


2017 NEC and Related
2017 NEC
Now Available!

Recent Posts
International Wire Colour Codes
by Tjia1981
Yesterday at 09:09 PM
Son of Sparky
by HotLine1
10/20/16 07:43 PM
Speaking of Plugmold ...
by gfretwell
10/17/16 02:37 PM
Broken battery charger? Check for cobwebs!
by gfretwell
10/17/16 02:30 PM
230 or 345 kV transmission lines?
by annemarie1
10/12/16 01:23 PM
New in the Gallery:
12.5A through 0.75mm˛ flex (just out of curiosity)
Shout Box

Top Posters (30 Days)
gfretwell 11
HotLine1 6
renosteinke 6
ghost307 5
Potseal 4
Who's Online
0 registered (), 159 Guests and 4 Spiders online.
Key: Admin, Global Mod, Mod
Topic Options
Rate This Topic
#102481 - 04/01/06 04:26 PM Load Calculations
teck_ed Offline
Junior Member

Registered: 12/26/05
Posts: 6
Loc: thorold
I have a 100 amp 3 phase service commercial building. The customer wants to open a tanning salon with 4 beds. 1 is 60 amp, 220 vac, 2 @ 20 amp 220 vac and 1 is 30 amp 220 vac. Also some lights, plugs and A/C 20 amp 220 vac. Is the 100 amp 3 phase service big enough? Your help is appreciated.

2014 / 2011 NEC & Related Books and Study Guides
#102482 - 04/02/06 06:46 AM Re: Load Calculations
bigrockk Offline

Registered: 01/25/03
Posts: 175
Loc: Middle of Canada
Hello ED
Check out section 8 of the code book paying paticular attention to 8-210 and table 14.These will help you determine your service and feeder sizes.

You will need to know the outside dimensions of the building to calculate a basic load and then you will have to add in all of the "special" loads.
When determing the current draw of a paticular machine or piece of equipment make sure you check the " data plate" on the machine for this info and do not go by the breaker size it is connected to.
Hope this helps.

#102483 - 04/05/06 05:03 PM Re: Load Calculations
marsbar Offline

Registered: 04/04/06
Posts: 31
Loc: london, ont, canada
Is you 100amp 3ph coming in at 600v? Bigrockk is right you should do a building calc. to be sure.

#102484 - 04/05/06 08:43 PM Re: Load Calculations
bigpapa Offline

Registered: 03/18/06
Posts: 75
Loc: canada
You dont need to do any demand calculations.

The simple answer is no. Add up the KW for each load and find the total current. Its about 87A just for the beds.

#102485 - 04/06/06 05:05 AM Re: Load Calculations
jay8 Offline

Registered: 07/28/05
Posts: 183
Loc: Vancouver, BC
re bigpapa's reply, you still need to refer to table 14 to establish your basic load, then as 8-210 tells us,"special loads .....based on the rating of the equipment installed with such demand factors as are permitted by this Code." Since your existing service will not be large enough, you still need to get out the calculator to determine the appropriate service feeder size.


ECN Electrical Forums - sponsored by Electrical Contractor Network - Electrical and Code Related Discussion for Electrical Contractors, Electricians, Inspectors, Instructors, Engineers and other related Professionals