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

>> Home   >> Electrical-Photos   >> Classifieds   >> Subscribe to Newsletter   >> Store  
 

Photo of the Week:

Unsafe Ladder
Is This Safe?

Advertisement:-Left
Recent Gallery Topics:
What in Tarnation?
What in Tarnation?
by timmp, September 10
Plumber meets Electrician
Plumber meets Electrician
by timmp, September 10
Who's Online Now
0 members (), 66 guests, and 23 robots.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate Thread
#211863 11/18/13 05:37 PM
Joined: Feb 2001
Posts: 308
S
Steve T Offline OP
Member
I am looking at a wiring schematic for a control system for a residential HVAC system. There are two different designs, the second stating it is for upgrading from single to two stage air conditioning. This second design shows what I'll presume to be a Class 2 transformer (among other devices), with one line of the load side noted to 'Connect Common to electrical ground', and a standard line drawn with ground symbol at end. Where can this electrical ground occur? Thanks.

Horizontal Ad
Joined: Jun 2004
Posts: 1,273
T
Member
Load side to ground?

Something's wrong.

Please upload the instructions.



Tesla
Joined: Feb 2001
Posts: 308
S
Steve T Offline OP
Member
I sent it to the 'Photos@ECN' email. Is there an easier way?

Joined: Feb 2001
Posts: 308
S
Steve T Offline OP
Member
Thanks for the instructions Trumpy. I can't reduce a scan to smaller than 100KB to attach.

http://www.fast-stat.net/images/pdf/Model%203000%20Installation%20Instructions%20Set.pdf

See installation Guide B-- "...Grounded Commons Wiring Method..."

Joined: Jun 2004
Posts: 1,273
T
Member
Dinky 24VAC 1-phase control transformers are typically fed 120VAC -- regular way.

On their (typically unfused) secondary side one wire is normally 'anchored' to ground whenever a floating neutral must be shunned. (It's not at all unusual for these circuits to 'float' -- not being grounded at all. Think sprinkler controls, door bells, etc.)

The other lead will then become the 24VAC 'hot.'

The pigtail implied in Section B can be landed upon any chassis that is also bonded back to the panel. The amount of current is tiny -- and at a very low voltage, too.

The gadget (Nordic Electronics Fast Stat) is plainly designed to get around old work limitations -- particularly those homes that started life with mere two wire control connections from the thermostat to the furnace.

So one drops in what is best described as a digital multi-plexer and de-multi-plexer pairing. As is typical in digital systems, a floating neutral/ground basis is undesirable, hence the grounding pigtail.





Tesla

Link Copied to Clipboard
Advertisement:-Right


Tools for Electricians
Tools for Electricians
 

* * * * * * *
2023 National Electrical Code (NEC)
2023 NEC + Exam Prep Study Guides Now Available!
 

Member Spotlight
Posts: 362
Joined: April 2003
Top Posters(30 Days)
Popular Topics(Views)
339,638 Are you busy
264,989 Re: Forum
246,232 Need opinion
New Page 2
Powered by UBB.threads™ PHP Forum Software 7.7.5