Heat Tape + Foil Tape = Dangerous Inductance

[dr del]

I had this on the last rack.

Cover the ends of the heat tape with non-conductive tape first and then, on top of that, use more foil tape to connect the front and back strips of the foil in the pic and the problem disappears.

[Montypython696]

I've been shocked only once when I was building my first rack. Needless to say I take every precaution I can now!

What I do is use black electrical tape to tape down heat tape. Then I go over the electrical tape with foil tape. I haven't had any problems since!

[satomi325]

Sounds like you may have an area on your heat tape that isn't completely sealed.

I haven't ever been shocked by foil tape before and I touch it all the time.
My ends are sealed with electrical tape, then the heat tape is secured down in the rack by the foil tape.

[kylearmbar]

Ive tried duct tape on heat cable, it seems to slowly erode away because of the elevated temps.

[blk02ssmonte]

I built my own rack and used THG heat tape. I soldered all connections and taped both ends with electrical tape. then used foil tape to hold it down. As long as the cut portion and soldered part are sealed there should not be any shocks.

[PitOnTheProwl]

You did something wrong or have a bad section.
Never had any problem here and I use either a 6 inch or 12 in piece of 12 inch wide per shelf so I have a lot of soldering and tape going on.

Everyone recommending electrical tape to hold down teat tape, electrical tape really only sticks to itself and not great at that either.

[lilnash0]

Use blue painters tape.. Cheap and effective!

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[adamfritzsche]

100 volts seems a little high, im around plenty of 480v circuits twirling next to each other almost daily, sometimes for hundreds of feet. Which yes they create enough inductance to set a tick tracer off, but 3 volts is the most I have measured. getting 100 volts induced in a couple feet, running in a straight line? I can buy some foil tape tomorrow and do my own test, but I find it extremely hard to believe it is inducing that much. A bad connection to the heat tape would easily do that though.

Yeah, I thought that was crazy myself. As an electronic technician by trade, when I first noticed this, I thought for sure there had to be a short somewhere causing this. I am still finding it hard to believe that this heat tape is that efficient at creating inductance. But then again, if you think about what this stuff is electrically, its one large linear length of coil wire.

I will note that this rack does have THG heat tape on it. The others where I am seeing 20V are flexwatt, but like I said are only running at 30% power. I am also going to do some testing at full power with a few strips of both tapes to see what I can come up with.

I noticed a few times while soldering up some heat tape the rosin core boiled out of the solder and spit around. where it landed it left tiny little burns in the heat tape. and when I put that piece in like usual thinking the tiny little pin hole would be fine it shocked me. if you soldered your tape I would bet money that is where your short is coming from and the reason your getting shocked by it.

I have soldered some of my racks in the past, but the one in question, I used the actual connectors.

I had this on the last rack.

Cover the ends of the heat tape with non-conductive tape first and then, on top of that, use more foil tape to connect the front and back strips of the foil in the pic and the problem disappears.

My ends are all covered with electrical tape, and on top of that, I do not take the foil tape all the way to the edges, just to prevent issues like this.

You did something wrong or have a bad section.
Never had any problem here and I use either a 6 inch or 12 in piece of 12 inch wide per shelf so I have a lot of soldering and tape going on.

Everyone recommending electrical tape to hold down teat tape, electrical tape really only sticks to itself and not great at that either.

That is what I thought myself, but every piece of heat tape I have does this where foil tape is used.

[dr del]

Yep,

You made the perfect inductive plate with no outlet to ground.

Trust me linking the back and front pieces of foil tape will fix it by giving it the needed outlet.

[OhhWatALoser]

Well I was surprised in more way than one, but for starters, I need to eat my own words:



measuring 60 volts across a 1 foot piece of heat tape. but here is the odd part:



I wasn't able to actually shock myself even with wet fingers, I didn't take a picture but I even did something stupid and stuck my tongue in between them, still nothing. I also could not get a wiggy to read the voltage and I know that will read 24 volts, yet the digital said there was 60. So honestly, I don't know whats going on. Maybe I should try a longer piece of tape and see if I can get something to hit me or at the very least set the wiggy off.

Some other things to note: The above pictures are with foil tape over the bus bar. If i moved the tape to the side, but still holding the heat tape down, i only got 7 volts


smaller piece over the bus, at 22




even smaller, I got 10,


smaller piece and outside of the bus, only 1 volt


adding a bridge still left potential between the ends


just showing it is highly conductive:


120v feed


I got a busy rest of the day, I'll lay out a bigger piece and see what I can do tomorrow. Still find it odd I could not shock myself with 60 volts even with my tongue.