T5HO Individual Reflectors Induced Voltage

[Mike31154]

I like to think I know a little about electricity having been an Instrument Electrical tech in the Canadian Air Force for most of my working career. Here's a new one for all you electrical buffs and stray voltage measuring dudes & dudettes.

I've read more than one thread regarding stray voltage in fish tanks and how to deal with it so I finally decided to do a few checks on my own system. I don't have a grounding probe but all the equipment running on the system is fed through a GFCI, two actually for a little redundancy. In any case, voltage reading between water and ground is around 36VAC which is a number I've often seen posted and I'm not too concerned about it. There are only two items in my tank that are submerged and have an electrical cord coming out of them, the 300W heater and a small powerhead circulating water through my DIY counter current air stone cheapo skimmer (which works well btw).

Here's something I haven't seen posted. My 4x 54Watt T5HO retrofit lighting system is fairly close to the water surface and I've noticed a few times getting a little tingle when my arm touches one of the indivdual reflectors and my hand is in the water at the same time. The reflectors are clipped on to the fluorescent bulb with the standard white painted metal clips but instead of using the metal screws to hold the clips to the reflectors, I chose to use nylon screws/bolts. Figured there would be less issues with rust even though the supplied hardware looked to be stainless steel. Ok, so since I felt this tingle and had the voltmeter out I decided to measure voltage between one of the reflectors and ground. How does 190VAC sound? That's a bit high no? Keep in mind the reflectors are pretty much physically isolated from any other electrical source other than the clips on the bulb.

So any fluorescent light experts out there that might be able to explain this phenomenon? Is it possible for a 48" T5HO lamp to induce that amount of voltage in a reflector mounted to it? Well, I guess it is possible, I measured it. But how? What's the science behind that?

I'm thinking of tying each reflector together with a small shorting cable and grounding the whole shebang to bleed this off.

 

[bmxdad]

I had a similiar event on my VHO reflector, didn't take a voltage reading but was getting a tingling feeling. MH and VHO reflectors are all now grounded. this seems to have taken care of the problem. am interested in answer if anyone has one
thanks

 

[DougSupreme]

could be an issue of salt creep causing a current path from the socket to the reflectors. ground everything anyway.

 

[A.T.T.R]

i get this alot with a t8 sytem with a metal backing.
sometimes i got a STRONG shock but . its an induced voltage so i dont worry about it


i forget if its the fact taht its AC that causes this like how a transformer works or if its just from the saltwater and lamps acting like plates in a capacitor or both.

 

[Icefire]

It's not induced voltage. Fluorescent and MH create high amound of electrical interference and reflector act like an antenna.

I can't currently mesure PH in my aquarium/sump because my T5 reflector aren't grounded. (getting new reflector this week so waste of time).

That's why 99% of voltage we see in our tank are doing nothing. What is dangerous is a leaking pump/heater, putting 120v directly in the water.

That's why I don't believe in stray voltage problems unless you got 120v AC in the water.

 

[Mike31154]

<a href=showthread.php?s=&postid=14249172#post14249172 target=_blank>Originally posted</a> by A.T.T.R
i get this alot with a t8 sytem with a metal backing.
sometimes i got a STRONG shock but . its an induced voltage so i dont worry about it


i forget if its the fact taht its AC that causes this like how a transformer works or if its just from the saltwater and lamps acting like plates in a capacitor or both.

Thanks all for the responses. The capacitor theory seems to make sense, with the reflector being one plate and the bulb the other. With respect to salt creep, there is some but I would think that would actually complete a circuit and bleed off stray voltage? No idea how the ballast modifies the 115VAC line voltage or current to fire the fluorescents, but I presume that the voltage is stepped up considering the high readings I got, close to 200VAC.

 

[devgru]

i had the same problem with my VHO's.i daisy chained them together with 14g copper ground wire and it worked great.

not that it could be causing your problem but i also ran dedicated circuits to tank equipment(4 15a for lighting,only using 2 tho),2 15a for return/closed loop pumps.and finally 2 for all other equipment

 

[Sisterlimonpot]

I realize this is an old thread but...

First thing I thought of was salt creep as well, not that it's a good conductor but the other minerals that might be present would be. I'm curious if you were to clean the bulbs removing all the salt creep and conducting the test again to see if it changes.

 

[letsgofishin]

yeah!!! old thread resurected!! whooo whoo

my 'theory' is that flourescent fixtures have transformers not only for voltage but also for frequency... it is an uber high frequency to keep the bulb 'firing'...

this high frequency is sufficient to create a voltage leak? that goes along the surface of teh bulb an dany other 'insulator'

if you look at high voltage lines in tghe street coming off of transformers you will see a series of insulators, and they are shaped like mushrooms? and they are stacked. so that the voltage has to go over the surface and up and down and in and out a bunch before it is connected to the pole... actually the insulators are holding the wire to the pole, and keeping the wires 'taught'? and the reason for the insulators is to keep the leaking voltage from climbing down the pole... basically creating a longer 'path' to ground?


anyways, so much for my 'theory'


thread can go back to sleep...