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.
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- 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.
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.
Re: Swim Meet#99957 09/28/0609:22 AM09/28/0609:22 AM
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.
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.