ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
ShoutChat
Recent Posts
Do You Wrap Your Receptacles?
by gfretwell - 02/20/24 10:48 PM
Cable Chase Code Requirement
by renosteinke - 02/16/24 07:00 PM
Do we need grounding?
by gfretwell - 02/16/24 10:37 AM
Cordless Tools: The Obvious Question
by gfretwell - 02/08/24 07:28 AM
Is this really a thing
by renosteinke - 02/07/24 01:15 PM
New in the Gallery:
This is a new one
This is a new one
by timmp, September 24
Few pics I found
Few pics I found
by timmp, August 15
Who's Online Now
1 members (Scott35), 46 guests, and 17 robots.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate Thread
#13816 09/12/02 08:09 AM
Joined: Sep 2001
Posts: 8
B
buddy Offline OP
Member
Why is the requirement in 110-27, that live parts greater than 50 volts be guarded? There have been fatalities, although small in number at less than 50 volts. So where did 50 volts come from?

#13817 09/12/02 10:24 AM
Joined: Oct 2000
Posts: 2,749
Member
See ARTICLE 720 Circuits and Equipment Operating at Less Than 50 Volts

Been in the code for many years, and probably was the basis for the voltage indicated.


Joe Tedesco, NEC Consultant
#13818 09/12/02 02:56 PM
Joined: Aug 2001
Posts: 7,520
P
Member
50V has also been a threshold in some parts of the British "code."

#13819 09/16/02 08:52 AM
Joined: Sep 2001
Posts: 8
B
buddy Offline OP
Member
I was told that 50 volts came into the code because 48 volts is what is used for telephone/communication circuits.

#13820 09/16/02 02:14 PM
Joined: Aug 2001
Posts: 7,520
P
Member
I think it's more to do with the calculation of the likely maximum current available with 50V based on "average" body resistance (if there is such a thing, based on another thread).

The DC supply for telephones is generally 48 or 50V, but the AC ringing supply can be 90V or more.


Link Copied to Clipboard
Featured:

Tools for Electricians
Tools for Electricians
 

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

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

 

Member Spotlight
Scott35
Scott35
Moreno Valley, CA. USA
Posts: 2,723
Joined: October 2000
Top Posters(30 Days)
maxecn 5
Admin 3
Popular Topics(Views)
317,956 Are you busy
242,876 Re: Forum
226,875 Need opinion
Powered by UBB.threads™ PHP Forum Software 7.7.5