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RE HELP! Stray voltage and grounding probes
"Whenever the fluorescent s light come on, I am not longer able to get
stable pH-reading from the sensor. The readings go back and forth
6.80 and 6.85 while switching CO2 supply on and off almost continuously
(switch hysteresis is 0.05). I attribute the cause for this to stray
voltages induced by the lighting"
The problem could as well be stray radio waves from the flourescents.
(All flourescents that run on AC emit radio waves.) If so, if the
reflector is not grounded, you try attaching a wire to it and to the
mains ground. You can also try wrapping the grounded wire around the
wires going from the ballast to the lamp sockets, one wind per every
inch or so will usually shield the wires adequately.
As for a grounding probe, any titanium or stainless steel rod that is
connected to the mains ground with a 16 gauge or better wire is
adequate. Ground probes that cost $20 or so are just that and nothing
more. There biggest advantage is that the wire-to-probe connection and
wire to plug connection are made for you. And you don't have to know
what ground is. You can connect the grounding end to the screw in the
center of the electrical socket faceplate (that connects to the mains
ground) or to the ground pin in a new three prong electrical plug.
Before you work with anything electrical near water, be sure your
aquarium electrical appliances are routed through a GFCI (Ground Fault
Circuit Interrupter). If you can't afford to have an electrician
install one, and you can't do it yourself, you can get an extension
cord that offers ground fault protection from That Fish Place ("FIRE
SHIELD EXTENSION CORD 8' TRC"). . That Fish Place and other vendors
also offer a few other GFCI options.
The TRC cord doesn't offer all of the same protections as a UL approved
GFCI will, but offers pretty good protection from most ground fault
situations. An advantage is that this cord's ground fault device
doesn't need to be reset if the AC power goes off. Most GFCIs on cords
for are intended for use with power tools and DO need to be reset if
the the power goes off. While this is safer for using power tools (in
case someone trips over a wire on a construction job site and then
plugs the wire back in without telling you), it's not so good for
aquaria. If the GFCI needs to be reset after any power outage, then
any momentary power outage will shut down your aquaria electrical
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