ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
ShoutChat Box
Recent Posts
Can I ask for your input?
by electure - 01/16/21 07:04 PM
From an outsider- How does tipping work?
by Trumpy - 01/16/21 06:52 PM
Ground fault remover :-)
by NORCAL - 01/16/21 10:29 AM
Photo Editing Software?
by grich - 01/13/21 11:18 AM
Happy New Year Folks!!!
by Trumpy - 01/04/21 05:46 AM
New in the Gallery:
Facebook follies, bad wiring
FPE in Germany pt.2
Who's Online Now
0 registered members (), 21 guests, and 18 spiders.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate Thread
Is there enough capacity? #180932 09/17/08 05:12 AM
Joined: Feb 2008
Posts: 193
S
schenimann Offline OP
Member
I had a post last month about 180 amp heat strips in a plant we work in. I went yesterday to talk more about the job with them. They potentially have five of these setups which would be 900 amps. They asked me if there was enough capacity with the existing service to handle this.

It is a 80 year old thread plant. I am trying figure out a way to determine their capacity.

Could I look at their power usage over the last year and compare that to their current service size and capacity to determine what they are using or is this the wrong approach. Do I need to physically monitor power for different panels and do a load calculation? If so, what is the best equipment for this?

I know some of of you guys do this sort of thing. Your help is appreciated.

Work Gear for Electricians and the Trades
Re: Is there enough capacity? [Re: schenimann] #180933 09/17/08 05:37 AM
Joined: Mar 2005
Posts: 1,213
S
SteveFehr Offline
Member
The kWh on the power bill may give you an idea, but you can only calculate the average demand, and not peak current. Has the meter recorded peak current demand? If not, that's your first step. The best way is to hook up a power quality analyzer (or similar) on their service and leave it there for a year. That will tell you peak demand, as well as a wealth of other information like power factor and transients.

Even this analysis doesn't give the true full picture; I will never design to more than 80% capacity to allow for unplanned surge.

A spot check with an ammeter may give you an idea of capacity, and in some cases may be good enough (if they have a 3000A service and 100A of load, I think you're OK.) It may also give you an easy "no" answer if they're drawing 1200A on a 1500A service. But if it's in between, you must consider that HVAC load can be more than the rest of the building put together, yet only shows up on the hottest/coldest days of the year.


Featured:

2020 National Electrical Code
2020 National Electrical
Code (NEC)

* * * * * * *

2020 Master Electrician Exam Preparation Combos
2020 NEC Electrician
Exam Prep Combos:
Master / Journeyman

 

Member Spotlight
watersparkfalls
watersparkfalls
Washington...Not DC
Posts: 236
Joined: March 2005
Show All Member Profiles 
Top Posters(30 Days)
Trumpy 15
NORCAL 9
Popular Topics(Views)
273,897 Are you busy
207,643 Re: Forum
195,377 Need opinion
Powered by UBB.threads™ PHP Forum Software 7.7.3