Good afternoon all – I need advice on how to build a faraday cage for my 600w ballast… Cable people sez there’s alot of interference coming from my basement – …I can build a cage – all I need to know is what gauge copper mesh and size.
I would think more a faraday cage made with copper sheet, it will be much more efficient or with 4 to 5 layer of heavy duty aluminum foil and the box should be at least 3 times the size of your ballast, for a better heat dissipation ,
However, if you go with a mesh, 25 micron copper mesh is a minimum , but be advise that you are gone a have interference leaks with a mesh. The size of the box can be downsize to the double of your ballast , less need for heat dissipation .
To avoïd painful mathematics equations, just keep that simple, shall we😀.
What is causing the interferences is ElectroMagnetic Wave (EMW) and the wavelenght is less than 1 micron and are known as ElectroMagnetic Interference or EMI if you prefer
A copper mesh is good to attract and deflect sparks or lightning but let passsome of the EMW. A 25 micron copper mesh will absorb some of the EMW, however, leaks are unevitable. However it can be suitable for protecting the HID light.
A copper sheet or a couple layers of heavy duty aluminum foil will block (cancel) the EMW and in bonus will protect against an EMP (ElectroMagnetic Pulse)
You can shield an entire room but hey, that will be more costly
Hoping that I enlighten you a little @garrigan62 on the subject
And here’s more information to look for before doing anything @MotaMan
Ensuring proper ground connections for all electrical devices will shunt high frequency interference to an earth ground or common. If grounding is not done properly, cables, grounds, or electrical equipment can act as a very powerful antenna, radiating out a strong EM field. Grounding the fixture and ballast to a common earth ground will help prevent this from occurring.
The length of wire leads between source and device should be as short as possible. Since this is not always possible in the case of remotely mounted ballasts, twisting cables together will help to cancel out the EM fields generated by long runs of cable. Using cable turns with paired power cables or input leads will generate opposing induced currents, minimizing or removing EMI generated by the runs. You should also avoid large loops or wire bundles, either of which will act as an antenna.
Shielding and Filters
Additional components can be used to block or absorb EMI caused by other equipment. Cable runs should be placed in metal conduits, and fluorescent or HID lights can be housed in luminaires with copper mesh or conductive glass to shield against EMI generated by the cables or lamps. All exposed conductors should be shielded. The conductive material of the shielding will absorb the EM field and prevent radiated or conducted EMI. Additionally, EMI filters or ferrite cores can be placed on ballasts, power conductors, and cabling to reduce conducted EMI across the length of the cable.
Simple alternatives, such as relocating the susceptible devices (e.g. moving a radio outside of the generated EMI field) are also feasible. Changing or replacing the fixture design, using an alternative ballast, reducing lamp wattage, reducing the inductive or capacitive load (or a ballast’s lamp load), or changing the layout of grounded components are all viable methods for reducing EMI within a system.
“Have you heard someone growing marijuana say they’ve gotten a visit from the police and it was oddly just before harvest? If you’re growing marijuana and using HPS (High Pressure Sodium) lamps and ballasts, you may be playing your local police department’s favorite tune. A HPS fixture, more to the point, the ballast, could be leading law enforcement right to your door. These ballasts are emanating RFI (Radio Frequency Interference) and this RFI can be detected with ham radios. Police are reportedly utilizing ham radios to listen for electromagnetic interference (EMI) and pinpoint the exact location of a grow operation as easily as turning their radios on to an AM station.”
This link is to a .pdf download file about finding the RIF origin
I believe it’s only the new electronic balists that do that… the old school magnetic ones don’t… although they do put off some heat… but I believe there is only 2 electronic balists on the market that have protection built into them for this reason… so do your research before buying my friend’s…
Thanks one and all ILGM followers – I’m gonna try the heavy duty foil. My ballast sits in a old metal aquarium stand - going to enclose this in the foil – heat dissipation should be ok with the size of the structure… Otherwise I’ll just have to live with the interference if I have any after my modification.
@Niala has brought up a good point as far as your wiring maybe not being grounded… I would suggest that you get one of these tools , they’re not expensive and It can help you in the future with a lot of different projects… but for sure it will at least tell you if the wiring behind the wall was done correctly …
I see your point – but probable cause is not just a radio signal and a high electric bill , coppers have to have something to go on … plus I can see multiple ballasts being a problem, I just have the one but I do know a signal is a signal - they just can’t tell what is goin on behind closed doors…
Thanks for the update, I had read you can test with a radio set to AM if indeed there is interference , I will have to reread article and give a test with that.