ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
ShoutChat
Recent Posts
Anybody comment on materials pricing?
by gfretwell - 06/10/21 01:33 PM
2 pole GFI feeding 1 and 2 pole loads
by gfretwell - 06/04/21 02:27 AM
Lock-down Thread
by HotLine1 - 06/01/21 08:15 AM
Updated Forum Software
by Admin - 05/31/21 12:09 AM
Square D "All-In-One" Panelboard
by HotLine1 - 05/29/21 12:13 PM
New in the Gallery:
2020 - 2021 Winter Project
2020 - 2021 Winter Project
by Bill Addiss, April 29
Garden 2021
Garden 2021
by Bill Addiss, April 26
Who's Online Now
0 members (), 39 guests, and 15 robots.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate Thread
#91371 01/12/05 02:16 PM
Joined: Nov 2001
Posts: 75
B
Bill39 Offline OP
Member
OK guys, I need ideas on how to provide a safe & NEC compliant installation for the following:

Customer makes water faucets and has several test stands that are actually sinks with electro/pneumatic actuators that hook up to the knobs and levers on faucets. The solenoids are 24VDC and the motors are 90-100VDC. Everything is within sight of the main control panel, about 10 ft. away. There is a main disconnect on the panel and separate fuse blocks inside for the individual motors, etc.

Water will be flowing out of the faucets into the sinks while the actuators are moving and energized. Cords from a wireway connect to the test stand to feed power to these units. Each of these cords has a female cord cap on it to connect to the test stand.

What really concerns me is that the 90-100VDC cords from the wireway are long enough to fall into the sink when they are disconnected. Due to the test stand design, the cords cannot be shortened. The area is only accessible to qualified personnel. Shutting off the main disconnect to connect or disconnect one cord is not feasible because it will interrupt testing on other units. I’m thinking separate disconnects will need to be added and the customer should provide employees with a written procedure for working on this equipment. What else????????

Thanks in advance for your ideas.

2017 / 2014 NEC & Related Books and Study Guides
#91372 01/25/05 03:47 PM
Joined: Jul 2003
Posts: 18
C
Member
Bill,
In my plant, this would be considered a "piece of in-house built (test) equipment". Some of this equipment can be the size of a large workshop. It's all one piece of utilization equipment. Then, we would not necessarily build to NEC. We always build to comply with OSHA standards. We have internal corporate safety standards that we follow in some cases. In others, we follow NFPA79, with local modifications, under the direction of our Electrical Safety Engineer. The wiring to the disconnecting means is the responsibility of the Plant Electrical Inspector (plant AHJ/NEC). Downstream, it is the Safety guy (equipment AHJ/NEC only as applies to utilization equipment). We often use NEC wiring methods, but it requires engineering judgement and careful risk assessment. Since the equipment is only accessible to qualified personnel and the control panel controls all the "stuff" then we would call the whole test stand the utilization equipment. The place it gets interesting is the qualifications of the folks working on the equipment and their status WRT OSHA for LOTO and with the written procedures on how to operate the test equipment, including procedures on how to change the Object Under Test. Remember, pressurized water can be a form of hazardous energy, not just the electricity. IMHO, this is where you get into what we call Equipment Engineering in my industry.
When I have to engineer something like this, I like to put GF sensors and use isolated LV for the actuators. I have actually found 24VAC to be safer than DC because of the ease with which one can sense a ground fault. Plus, you can get better actuation with less power and corrosion. I would throw in a low force cable retractor hooked to a Kellums grip on each cord to yank it up out of the way when disconnected for an added safety bonus. If its just the falling in the sink hazard, then maybe that's all you need? Just my 7.5 cents...
Jim


Link Copied to Clipboard
Featured:

Tools for Electricians
Tools for Electricians
 

* * * * * * *

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

 

Member Spotlight
Posts: 165
Joined: March 2007
Top Posters(30 Days)
Admin 11
Trumpy 10
Popular Topics(Views)
280,304 Are you busy
213,394 Re: Forum
200,331 Need opinion
Powered by UBB.threads™ PHP Forum Software 7.7.5