ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
Top Posters(30 Days)
Potseal 11
Recent Posts
600 KW 120/208 3 Phase Y protection
by Yooperup. 07/21/17 09:27 AM
1913 American Electrician's Handbook
by gfretwell. 07/20/17 01:08 PM
Green House wiring
by ghost307. 07/20/17 09:10 AM
Permit Snafus...AHJs and Contractors Jump in
by HotLine1. 07/18/17 08:06 PM
New in the Gallery:
SE cable question
Popular Topics(Views)
239,222 Are you busy
174,620 Re: Forum
167,046 Need opinion
Who's Online Now
0 registered members (), 69 guests, and 8 spiders.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate This Thread
#134636 - 11/24/02 12:11 AM Air Con/HVAC systems  
Trumpy  Offline


Member
Joined: Jul 2002
Posts: 8,217
SI,New Zealand
Anyone need any advice about air-conditioning systems and general HVAC systems?.
My company installs these systems all the time and I normally end up wiring them,
any questions on how these systems actually work?. [Linked Image]


Let's face it, these days if you're not young, you're old - Red Green grin

Test Equipment:
Large Selection of Test Equipment For Electrical, HVAC, Test & Measurement
Large Selection of Test Equipment For Electrical, HVAC, Test & Measurement

#134637 - 11/24/02 08:59 AM Re: Air Con/HVAC systems  
sparky  Offline
Member
Joined: Oct 2000
Posts: 5,311
I am often confused about proper OCPD sizing


#134638 - 11/24/02 12:44 PM Re: Air Con/HVAC systems  
golf junkie  Offline
Member
Joined: Apr 2001
Posts: 507
York, NE
Sparky,
We always size the feeder and OCPD by the max. fuse/breaker rating on the nameplate. That insures plenty of ampacity for startup.

Where it gets more difficult is on remodels where older HVAC units without the nameplate info are being reused. Then it often becomes a guessing game.

GJ


#134639 - 11/24/02 11:13 PM Re: Air Con/HVAC systems  
Bjarney  Offline
Moderator
Joined: Apr 2002
Posts: 2,527
West-Southern Inner-Northeast ...
Trumpy — In your region, what is the unusual breakpoint in rating for 1ø versus 3ø hermetic compressors in residential and light commercial facilities? 1ø is typical for up to 5 tons [60,000 Btuh] in the western US, although 3ø hermetic compressors are readily available in 2-or-3-ton up.


#134640 - 11/26/02 02:53 AM Re: Air Con/HVAC systems  
Trumpy  Offline


Member
Joined: Jul 2002
Posts: 8,217
SI,New Zealand
BJ, what do these Dots, indicate?.
Only after I find out this, can I give you a
real sort of answer?. [Linked Image]


Let's face it, these days if you're not young, you're old - Red Green grin

#134641 - 11/26/02 11:54 AM Re: Air Con/HVAC systems  
CTwireman  Offline
Member
Joined: Feb 2002
Posts: 840
Connecticut, USA
Trumpy,

I'm guessing you mean the circles with the lines through them. That's a symbol we use for convenience to say "phase."

So, it means "single phase" or "three phase."


Peter

#134642 - 11/26/02 03:24 PM Re: Air Con/HVAC systems  
Bjarney  Offline
Moderator
Joined: Apr 2002
Posts: 2,527
West-Southern Inner-Northeast ...
Sorry Trumpy. Apparently something didn't translate correctly. {Used Alt-0248 for a lower-case phi from Windows 2000 "Character Map."}

"Trumpy — In your region, what is the unusual breakpoint in rating for 1-phase versus 3-phase hermetic compressors in residential and light commercial facilities? Single-phase is typical for up to 5 tons [60,000 Btuh] in the western US, although 3-phase hermetic compressors are readily available in 2-or-3-ton and up."


#134643 - 11/27/02 02:03 AM Re: Air Con/HVAC systems  
Trumpy  Offline


Member
Joined: Jul 2002
Posts: 8,217
SI,New Zealand
Sorry about the confusion, guys!, should have known that one, at the very least! [Linked Image]
It really depends upon the load current of the unit to be installed and of course, the
type of supply available, as a few light commercial installations over here, only have a 100A single phase supply.
Given the choice, 3 Phase wins hands down, because of smaller cable sizes and the compressors run a lot quieter.
With regard to sizing the Circuit Breaker,
you must take into account, the Start-Up current, which can be anywhere from 7-10times FLA.
But new technology over here, means that, Soft-starter units are normally fitted to Air con units, to prevent the A/C, effecting things like computers, upon start-up.


Let's face it, these days if you're not young, you're old - Red Green grin


Member Spotlight
Joe Tedesco
Joe Tedesco
Boston, Massachusetts USA
Posts: 2,749
Joined: October 2000
Show All Member Profiles 
Featured:

2017 NEC and Related
2017 NEC
Now Available!

Shout Box
Powered by UBB.threads™ PHP Forum Software 7.6.0
Page Time: 0.013s Queries: 14 (0.002s) Memory: 0.7938 MB (Peak: 0.9548 MB) Zlib enabled. Server Time: 2017-07-23 02:55:34 UTC