ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
ShoutChat
Recent Posts
Increasing demand factors in residential
by tortuga - 03/28/24 05:57 PM
Portable generator question
by Steve Miller - 03/19/24 08:50 PM
Do we need grounding?
by NORCAL - 03/19/24 05:11 PM
240V only in a home and NEC?
by dsk - 03/19/24 06:33 AM
Cordless Tools: The Obvious Question
by renosteinke - 03/14/24 08:05 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
0 members (), 248 guests, and 16 robots.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate Thread
Page 1 of 2 1 2
#151164 07/27/06 11:58 AM
Joined: Jul 2006
Posts: 6
M
Junior Member
A question arose today and I am turning to you for an answer. If you turn off a 480V disconnect switch and open the door. Everyone understands that the top of the switch is still energized. However, if the switch is designed with an arc shield covering the lugs. Are they still considered to be exposed live parts?

The reason I'm asking is this would decide if our electricians have to wear full arc protection gear or not? Which is a hassle!

To elaborate on my scenario, The switch will remain open at all times. The only live parts are covered and protected by the plastic cover that is part of the disconnecting means. I've searched the NFPA 70E handbook but they do not cover this situation. I have to present my findings to the safety committee so any references you could supply would be helpful!

Thanks in advance for your responses.

Arc Flash PPE Clothing, LOTO & Insulated Tools
Joined: Mar 2002
Posts: 582
R
Ron Offline
Member
110.8(A) printed below, indicates "while they are working on or near exposed electric conductors or circuit parts that are or can become energized". The insulating plastic sheet covering the line side of the disconnect is not rated to withstand an arc fault, and the proper PPE should be worn when working on or near the switch, in the event that an arc occurs on the line side. JMHO
110.8 Working On or Near Electrical Conductors or Circuit Parts.
(A) General. Safety-related work practices shall be used to safeguard employees from injury while they are working on or near exposed electric conductors or circuit parts that are or can become energized. The specific safety-related work practice shall be consistent with the nature and extent of the associated electric hazards.

(1) Live Parts—Safe Work Condition. Live parts to which an employee might be exposed shall be put into an electrically safe work condition before an employee works on or near them, unless work on energized components can be justified according to 130.1.


Ron
Joined: Sep 2005
Posts: 120
Z
Zog Offline
Member
I agree with Ron. I had a customer with this exact same problem and I asked the 70E commitee chair about this exact senario and he basically said what Ron posted. I know thats not the answer you wanted to hear but thats what it is.


MV/HV Testing Specialist, "BKRMAN"
Joined: Jul 2002
Posts: 8,443
Likes: 3
Member
Steve,
Wouldn't you have to isolate the supply to the disconnect before opening it anyway?.
Ron is right though.

Joined: Jul 2006
Posts: 6
M
Junior Member
Thank you for your responses. It looks like there will be a few sweaty guys here from now on.

Trumpy, once you pull down the handle on a disconnect enclosure you can open the door. In the past it was considered safe as long as sparkey used common sense and stayed away from the top of the lugs. Those days are gone forever.

Joined: Dec 2005
Posts: 10
B
Member
FPL just had an accident where a 20 year old had turned off and Locked out the main, opened the panel, removed the screws from a buss to replace it, dropped a screw and BOOM.

He now has 3rd degree burns on his face and chest.

ANY live equipment is live unless the power source is also LOTO.


Bryan L. Key
Safety Inspector/Trainer
Terry's Electric Inc.
An Xcelecom Company
600 N. Thacker Ave., Suite A
Kissimmee, Florida 34741
Joined: Oct 2000
Posts: 2,723
Likes: 1
Broom Pusher and
Member
Wear the PPE!

Many EXO type Disconnect Switches may be opened, even if the Switch is still closed.

This is done via an auxiliary overiding cam/latch, which if turned or activated, allows the front cover to be opened while the Switch remains closed.

The purpose is to perform tests and/or view fuse data, without disturbing the load.
It is definitely for use by qualified personnel ONLY!!!

Just wanted to include this little 2¢

Scott35


Scott " 35 " Thompson
Just Say NO To Green Eggs And Ham!
Joined: Sep 2006
Posts: 2
R
Junior Member
I'll offer a contrarian opinion.

I think if there is no feasible danger of contacting the energized live parts on top (i.e. not pulling new wire into switch) the line shield should serve as an effective barrier to contact. That is it's function. It does not have to be made to resist blast, as it prevents blast from occuring by prevention. At some point, some allowance must be made for practicality; there is a point where safety is not increased significantly but added work goes thru the roof.

Let me hasten to add that if it is not a big problem to de-energize switch first, I'd do it, and ya still gotta make sure the load side is actually dead.

Joined: Jul 2002
Posts: 8,443
Likes: 3
Member
Good points RayS.
And Welcome to ECN!. [Linked Image]

Joined: Feb 2001
Posts: 54
T
Member
To elaborate on my scenario, The switch will remain open at all times. The only live parts are covered and protected by the plastic cover that is part of the disconnecting means. I've searched the NFPA 70E handbook but they do not cover this situation. I have to present my findings to the safety committee so any references you could supply would be helpful!

Ok, I'll bite, why would the covers "Have" to remain open at all times?
I open dis-connects all the time, for trouble shooting, to read fuzes, to replace fuzes, to trace circuits...etc.
But I only have the cover open while I am in front of it. or if I have a ckt tracer conected. or an clamp-on ammeter connected.

Page 1 of 2 1 2

Link Copied to Clipboard
Powered by UBB.threads™ PHP Forum Software 7.7.5