ECN Forum Forums Safety Discussion and News Safety News and Product Recalls laptop used in bathtub dangerous?

Yes, if it's an "electronic transformer" with an electrical path between input and output, then a ground fault could cause the GFI to trip, so long as it is a DC-sensing type. (Note that many will detect pulsing DC, such as you would get as the raw output from rectified AC, but they won't trip on pureDC).

Such power units aren't really transformers in the true sense of the word. With a real, genuine transformer with no direct electrical connection between the windings, a ground fault on the secondary will not trip a GFI on the primary.

Sparky,
You could even set up one of the SWER systems we were discussing some months back and have the secondary of the xfmr feed into the single wire. You could still put a GFI on the primary and it wouldn't trip, even though the full load current is flowing through the earth on the secondary side.

I see.. there is no direct connection to produce the imbalance necessary for the GFI to function, thanks Paul

What i don't understand is the rationale behind some NEC codes that would specify this to be so....

well guys this sounds like and experiment in the works

who has a spare transformer plug, a gfi protected outlet and a bath tub. lets find out for sure.

girl use the batteries or get the #@!! out of the tube life is to short.

She could use batteries... but what I was thinking was that if the laptop fell in the drink, would that make the batteries possibly short-circuit? An exploding lithium-ion battery sounds rather unpleasant, espicially if you're already nekkeid with no clothing to protect you. Yikes.

Plus... I mean... laptops cost between a thousand and a few thousand dollars!!! I mean, one splash, one slip, and the system could be toast!

Ironically, within the next few years we might see specially-designed terminals or computers for just this use.

(Goes off to invent the water-proof toaster.)

AlphaOperator,
while your at it, i'd really appreciate a breed of self-cleaning chickens

Common sense would say its a bad idea to use any type of electric device while on is sumerged in bath water.

Tell her to smarten up so we do not end up readng about her in the "darwin awards".

The situation described struck me as similar to that encountered in an operating room with a patient being operated on. I know that this person is not compromised from a health standpoint, but, she is compromised from an insulation standpoint. Meaning, the resistance of her skin has been reduced to the point that its resistance approximates that of the underlying tissue. To the point: the NFPA, the people that write the National Electrical Code, also write a code for health care facilities, NFPA 99. In this Code, in an operating room with compromised situations (such as this) they call for alarms on the electrical system whenever the voltage exceeds 20 milivolts and 5.0 miliamps. This is not to say that these values would be lethal to this person, or to a patient, however, they do represent safe values found through empirical evidence. However you view this, I believe that values significantly higher than these could easily be attained in this situation, whether or not the primary of the transformer is GFCI protected (they don't always operate at the proper levels). It doesn't pay to tempt fate.

Any body know of research into the effects of electric effects on thoroughly saturated skin. I have been hit with 120 and slightly wet hands (winter) with insulated boots, it is much more intense than with dry hands. Yes I am a sparky.

Isolated Power Systems Equipment
UL 1047, and NEC 517.140 may be helpful information.

Here is how we settle this...have a certified electrician install a "good" GFI outlet, plug the laptop into it and while standing on a dry floor away from the tub (noone in it) throw the laptop into the tub and see what happens. This is the only way to find out for sure...

Another thing to think about would be the backlight on the laptop screen. While the majority of the laptop circuitry operates on low voltage, the backlight behind the LCD screen is actually a small cold-cathode fluorescent lamp, running on a high voltage (200V+) supplied by an inverter circuit inside the laptop.

While power limited, such a power source could be dangerous to someone in a bathtub if it got wet....