ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
ShoutChat
Recent Posts
Increasing demand factors in residential
by gfretwell - 03/28/24 12:43 AM
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
1 members (Scott35), 271 guests, and 19 robots.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate Thread
#99953 09/27/06 06:12 PM
Joined: Jan 2004
Posts: 1,507
G
Member
I had the occasion to inspect wiring associated with a swim meet where the swimmers were racing against the clock as well as their competitors.
My question is based on the fact that they were using touch pads (millivolt) at the water level in the lanes where the swimmers would be swimming. These touch pads were hooked to the computers that would log the times. Has anyone ever run into this in their travels? I questioned this use and the shock hazzard. I was "assured" that this is standard procedure.


George Little
Stay up to Code with the Latest NEC:


>> 2023 NEC & Related Reference & Exam Prep
2023 NEC & Related Reference & Study Guides

Pass Your Exam the FIRST TIME with the Latest NEC & Exam Prep

>> 2020 NEC & Related Reference & Study Guides
 

#99954 09/27/06 10:45 PM
Joined: Jul 2004
Posts: 9,923
Likes: 32
G
Member
Was this battery operated or line voltage operated? I understand it may really be a distinction without a difference but you won't have the possibility of 120v present with a fault. Battery equipment is also less likely to have a voltage referenced to ground (and the pool)
I do understand a capacitive "touch" pad is passive in nature with no voltage present but we deal with the worst possible scenario.


Greg Fretwell
#99955 09/27/06 11:03 PM
Joined: Jan 2004
Posts: 1,507
G
Member
Greg- I don't know. They hit town, had their swim meet and left town before I was able to get the info. Seems it was going into the weekend and I thought I'd follow up on Monday and they were gone. I was hoping someone on this Board had some experience with something similar.


George Little
#99956 09/27/06 11:30 PM
Joined: Jul 2004
Posts: 9,923
Likes: 32
G
Member
I have heard about these systems on one of the BBs I am on and my impression was this was hanging on a laptop USB port. I am not even sure how the AHJ gets involved if they don't plug it in the wall.
It certainly doesn't sound any more dangerous than one of those LED blinkng light floaters that runs on 3 AA cells.


Greg Fretwell
#99957 09/28/06 09:22 AM
Joined: Jun 2001
Posts: 161
M
Member
OK guys, this is recollection from 8+ years ago...
If I remember right equipmemt approved for use in a swimming pool by UL (not a fountain) has to have a split wound transformer with the secondary on an insulated bobbin. This is where the primary and secondary windings are either on seperate bobbins on a common core or are wound on an insulating bobbin with secondary insulation between the windings (windings side by side). This is opposed to primary and secondary windings right on top of each other. The core was also to be grounded.
The theory, I guess, is that a fault on the primary would be cleared by overcurrent protection (short winding) or by ground fault (short to bobbin) while the secondary was still insulated from the core and primary.

Again, trying to remember from a while ago...


Mike Wescoatt
#99958 09/28/06 12:06 PM
Joined: Jul 2004
Posts: 9,923
Likes: 32
G
Member
These days it is hard to find a conventional transformer in a piece of electronic gear. They use switch mode power supplies. I would still be nervous if this timing device was plugged into the wall, no matter how it was listed.


Greg Fretwell

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