Conductivity of condensate

[al hildenbrand]

Setting: Dwelling bath with a blow dryer, unplugged, lying at the vanity. A person takes a shower long enough to fog the mirror, and, presumably, pretty much coat the inside surface of the bath with a thin layer of shower water condensate.

Problem: When the blow dryer is plugged in, a leakage current travels from the hot conductor through the condensate.

Question: What is the characteristic of this leakage current? Does anyone know of references, or has anyone had first hand experience with related issues, like the GFI not holding?

 

[bennie]

Re: Conductivity of condensate

Distilled water has a high resistance. The resistance of the fault path will be based on impurities on the wall.

28K ohms will allow 4ma current flow. Resistance above that amount will not trip a GFCI.

 

[bob]

Re: Conductivity of condensate

Al
Did someone feel the tingle from the leakage?

 

[charlie b]

Re: Conductivity of condensate

It sounds to me that the person tried to use the hair dryer, and it tripped the GFI. It seems to me that Al?s question is, ?Is it reasonable that this scenario would lead to a GFI trip, or should he be looking for another cause?? Is that right, Al?

Just in case that is the issue, let me start by noting that you are not dealing with ?condensate,? and you are certainly not dealing with distilled water. When water is heated to its boiling point (too hot for a bath!), it will evaporate, leaving almost all dissolved minerals behind. When it cools, it becomes condensate, and can be said to have been ?distilled.? That type of water is very pure, and not a very good conductor of electricity.

But most of the water that ?steams up? a bathroom during a hot bath or shower did not get airborne by the process of evaporation. The air simply picks up humidity by contact with the bath water. A shower does this even more effectively by spraying the water in droplets through the air. The water that is floating in the air has the same types of minerals that are present in the bathtub. That water is not pure, and is a good conductor.

So I would say that it is reasonable to expect a hair dryer that had been exposed to a ?steam bath? environment to trip a GFI.

 

[al hildenbrand]

Re: Conductivity of condensate

Charlie,

Yes, the question is, is it reasonable to believe a "steam" covered blow dryer will trip a GFI?

Perhaps my choice of "condensate" misleads . . .I'm not sure. The air of a bath will warm more rapidly in the presence of the hot water, either shower spray or in the tub, thus permitting it to support a higher humidity level. Most of the solid surfaces not in contact with the warm water will rely on the air to warm them in turn. When the conditions are right, the dew point will be at or above the wall surface temperature, the humidity in the air will turn into liquid water on the cool surfaces in the bath.

The water that condenses on the cool surfaces will be contaminated by the dusts and oils, makeup, hair,. . .whatever is already on the surfaces. It will also bring some stuff from the air, as well.

But, where's the ground fault current path? The path from the hot to the neutral will not be seen by the GFI sensor. Most blow dryers are two wire. . .no ground present in the cord or the cord cap.

Is it really reasonable to think that the person plugging in the blow dryer will provide path to ground, and not know it? In this setting, no one is commenting on a "tingle" or more. The only symptom commented on is the tripping of the GFI.

 

[bennie]

Re: Conductivity of condensate

The moisture may be getting inside the GFCI and creating an internal fault.

 

[steve66]

Re: Conductivity of condensate

I have a fluorescent light on a GFI (don't ask why), and it frequently trips the GFI when it is turned on or off (once every 2-4 weeks).

I suspect it is a cheap or defective GFI outlet, and it is falsely tripped by a surge or current spike when the light is switched on or off.

I'll bet your situation is similar. In other words, the tripping of the GFI has nothing to do with the condensate. Is the user plugging it in with the switch alreay set on high?

Steve

 

[charlie b]

Re: Conductivity of condensate

Originally posted by al hildenbrand: Is it really reasonable to think that the person plugging in the blow dryer will provide path to ground, and not know it? In this setting, no one is commenting on a "tingle" or more.

I think it is reasonable. A GFI can trip at currents as low as 3 milliamps. That may simply be too small a current to cause a ?tingle? sensation for the short time it takes the GFI to trip. I also think that Bennie?s answer gives a likely cause as well.

 

[al hildenbrand]

Re: Conductivity of condensate

I'm presenting this from two anecdotal accounts from two different parties in two different bathrooms. Regrettably, this is not first hand with me.

The claim is the GFI trips when the blow dryer is plugged in and used after a shower / bath when the room is steamy. The claim also is that the rest of the time the GFI does not trip.

Bennie's suggestion of moisture inside the GFI should lead to tripping at other times as well as when the blow dryer is plugged in.

I personally like Steve's suggestion of an overly sensitive GFI as the most probable.

One of the parties experiencing the blow dryer GFI tripping is a marketing analysis manager for a major manufacturer of GFIs (among other electrical hardware). He states the condensate provides the ground fault path. This gets me to my original question at the top of the thread.

While I could devise a Rube Goldberg sequence to trip the GFI with humidity condensate, I just don't see it. I have to assume the baths are standard. . .painted drywall on wood studs, water resistant floor most likely tile, plastic cover plates on the electrical. Basically, a lot of nonconductive surface with a microns-thin layer of moisture.

The marketing analysis manager does state that either the GFI receptacle or the blow dryer cord cap GFI will trip in steamy conditions, and not trip when things are dry.

[ March 18, 2004, 01:28 PM: Message edited by: al hildenbrand ]

 

[steve66]

Re: Conductivity of condensate

I won't accept that condensate can trip a GFI unless I have more than one outlet in one bathroom that trips with one hairdryer when used by one paticular person.

But I do like Al's suggestion about the Rube Goldberg. Has anyone watched the "Myth Busters"? They are probably just waiting for a reason to drop a plugged in hair dryer in a tank full of water and watch the fireworks

Steve

Steve

 

[iwire]

Re: Conductivity of condensate

Originally posted by Bennie:
The moisture may be getting inside the GFCI and creating an internal fault.

Bennie you and I are sharing the same thought.

 

[j.saraceni]

Re: Conductivity of condensate

When the shower is running and the bath becomes steamy, I think it's reasonable to keep the blow dryer in a drawer, a bathroom cabinet or out of the room completely. When the air is cleared of moisture via exhaust fan or open window then it is prudent for the dryer to be plugged in and used. I protect my Volt-Ohm meter in a case to keep moisture out ans also use packets of moisture absorbent desicant, to keep moisture out of the unit. Why would I not do the same with an appliance?