RF interference question on AV system

[trochetier]

I am considering installing a Level 2 charger on the back wall of my 2 car garage. The back wall is most optimum for charging either car without the cable getting in the way. However, my TV is wall mounted on the other side of the wall and the audio system sits just below it. They cannot moved due to the room design. So my questions are -

1. Do the charging units produce RF? If so, do they come with effective built-in RF shielding?
2. Are there NEC standards for RF shielding of the charging units?
3. Is there a way to determine the possibility of RF interference on my AV system before the charger installation?

 

[TLS Guy]

I am considering installing a Level 2 charger on the back wall of my 2 car garage. The back wall is most optimum for charging either car without the cable getting in the way. However, my TV is wall mounted on the other side of the wall and the audio system sits just below it. They cannot moved due to the room design. So my questions are -

1. Do the charging units produce RF? If so, do they come with effective built-in RF shielding?
2. Are there NEC standards for RF shielding of the charging units?
3. Is there a way to determine the possibility of RF interference on my AV system before the charger installation?

No idea, look it up.

If I have an oddball situation like that I do my own research and don't expect others to do it for me. The other issue is that I highly doubt there is data on that. So go ahead, and if it works fine, if not you are screwed. My hunch is that if your proceed with that plan you will be screwed.

 

[lovinthehd]

Big sheet of copper plate behind the gear in the garage may help?

 

[TLS Guy]

Big sheet of copper plate behind the gear in the garage may help?

It will likely induce eddy currents and not likely to help and may make it worse. If you really ground the copper plate, it might help, but I doubt it.

As I think about this, this arrangement is much more likely to induce a huge hum from mutual induction. I would say, that is pretty much a dead certainty.

 

[lovinthehd]

It will likely induce eddy currents and not likely to help and may make it worse. If you really ground the copper plate, it might help, but I doubt it.

As I think about this, this arrangement is much more likely to induce a huge hum from mutual induction. I would say, that is pretty much a dead certainty.

Would faraday cage be better use of copper? I thought copper shielding even in sheet form had some benefits, but way out of my pay grade. I'd hope the suppliers of the gear can answer the questions tho.

 

[TLS Guy]

Would faraday cage be better use of copper? I thought copper shielding even in sheet form had some benefits, but way out of my pay grade. I'd hope the suppliers of the gear can answer the questions tho.

With issues like this proximity is by far the biggest issue. With RF or induction problems will lessen by the square of the distance separating them. So doubling the distance will reduce the square of the interference.

The way the OP describes this, I have to rate the chance of a problem as high. The only way to find out is do it. The problem with that is that it probably can't be remedied without moving one or the other. With the expense and the issue of guessing this wrong, I personally would not risk it. In my view a major issue is more likely than not.

 

[trochetier]

Thanks for the replies. I did my research and found little to nothing about RF interference from Level 2 chargers and AV equipment close by. Hence my post. I was hoping someone here may have had first hand experience or knowledge. I guess not. Oh well!

 

[TLS Guy]

Thanks for the replies. I did my research and found little to nothing about RF interference from Level 2 chargers and AV equipment close by. Hence my post. I was hoping someone here may have had first hand experience or knowledge. I guess not. Oh well!

Eddy current AC induced hum will likely be the biggest issue in that arrangement. There will be a huge inductive field around a charging unit like that.

I suspect you are not getting a lot of info, as this is an unusual situation, as placing AV gear back to back on a unit like that would be highly unusual and certainly not to be advised.

As I stated, distance is your friend here, and moving the units further away from each other is the key. So if you double the separation your noise by induction and RF goes down by the increase in spacing squared.

I absolutely would NOT advise a back to back installation. I would estimate the chance of a significant issue in excess of 90%. So my strong advice is DON"T do that.

 

[EdwardKinney]

RF interference can be a real pain with AV systems—shielded cables and proper grounding often help.

 

[highfigh]

I am considering installing a Level 2 charger on the back wall of my 2 car garage. The back wall is most optimum for charging either car without the cable getting in the way. However, my TV is wall mounted on the other side of the wall and the audio system sits just below it. They cannot moved due to the room design. So my questions are -

1. Do the charging units produce RF? If so, do they come with effective built-in RF shielding?
2. Are there NEC standards for RF shielding of the charging units?
3. Is there a way to determine the possibility of RF interference on my AV system before the charger installation?

Contact the manufacturer of the charging unit- the FCC has rules about RF emission and if you have any kind of remote control, it's shown on the back- the full list is in the link. Basically, any device should accept interference but isn't allowed to produce it to the extent that it will negatively affect other devices. RF blockers for cell phones and Radar speed check aren't legal.

However, there are ways to minimize the strength of the RF using shielding.

Federal Register :: Request Access

www.ecfr.gov

 

[highfigh]

With issues like this proximity is by far the biggest issue. With RF or induction problems will lessen by the square of the distance separating them. So doubling the distance will reduce the square of the interference.

The way the OP describes this, I have to rate the chance of a problem as high. The only way to find out is do it. The problem with that is that it probably can't be remedied without moving one or the other. With the expense and the issue of guessing this wrong, I personally would not risk it. In my view a major issue is more likely than not.

Yes- the Inverse Square Law- double the distance, the strength drops to 1/4.

 

[TLS Guy]

Contact the manufacturer of the charging unit- the FCC has rules about RF emission and if you have any kind of remote control, it's shown on the back- the full list is in the link. Basically, any device should accept interference but isn't allowed to produce it to the extent that it will negatively affect other devices. RF blockers for cell phones and Radar speed check aren't legal.

However, there are ways to minimize the strength of the RF using shielding.

Federal Register :: Request Access

www.ecfr.gov

With that setup, electromagnetic interference will be a much higher risk than RF.

The only way he could deal with that is a Mu-Metal shield, which would likely be costly.

The transformer in the charging unit, will emit a significant electromagnetic field.

 

[highfigh]

With that setup, electromagnetic interference will be a much higher risk than RF.

The only way he could deal with that is a Mu-Metal shield, which would likely be costly.

The transformer in the charging unit, will emit a significant electromagnetic field.

Exactly (WRT MuMetal), but shielded transformers do exist, so they could be used.

I used MuMetal for shielding in some car audio systems- awfully sharp, but when used correctly, it did work.

 

[Eppie]

First that I've heard of it. Interesting.

Mu-metal - Wikipedia

en.wikipedia.org

 

[highfigh]

First that I've heard of it. Interesting.

Mu-metal - Wikipedia

en.wikipedia.org

If you ever need to use it, be sure to protect yourself- it's insanely sharp and very stiff.for its thickness. It's easy to solder a ground wire onto it, fortunately.

For RF, Copper screen can be used- it needs to be grounded. One use is to block radio transmission, into or out of a room or building that needs to be secure.

Faraday cage - Wikipedia

en.wikipedia.org

 

[Eppie]

If you ever need to use it, be sure to protect yourself- it's insanely sharp and very stiff.for its thickness. It's easy to solder a ground wire onto it, fortunately.

For RF, Copper screen can be used- it needs to be grounded. One use is to block radio transmission, into or out of a room or building that needs to be secure.

Faraday cage - Wikipedia

en.wikipedia.org

I could have used that years ago. I neighbour 3 doors down was a HAM radio operator with a tall antenna tower in his back yard. I could hear the chatter through my old Kenwood AVR on occasion. The house was a rental so he eventually moved away.

 

[Trell]

I could have used that years ago. I neighbour 3 doors down was a HAM radio operator with a tall antenna tower in his back yard. I could hear the chatter through my old Kenwood AVR on occasion. The house was a rental so he eventually moved away.

Did you ever try "--. --- ....... .- .-- .- -.--" when talking to him? It's supposed to mean "Go away"

 

[highfigh]

I could have used that years ago. I neighbour 3 doors down was a HAM radio operator with a tall antenna tower in his back yard. I could hear the chatter through my old Kenwood AVR on occasion. The house was a rental so he eventually moved away.

That's not an easy problem to solve. I lived near someone who was a HAM operator but the first was good about not causing interference- the second, not so much. I have had occasional interference in guitar amps since buying my house from the TV broadcast antenna farm about 2 miles away but that ended when analog became less used.

 

[Trell]

That's not an easy problem to solve. I lived near someone who was a HAM operator but the first was good about not causing interference- the second, not so much. I have had occasional interference in guitar amps since buying my house from the TV broadcast antenna farm about 2 miles away but that ended when analog became less used.

Generally it is an easy problem to solve but not when a HAM operator flexes his "muscles" (yah, it's always a male). You should know this, really.

 

[TLS Guy]

I could have used that years ago. I neighbour 3 doors down was a HAM radio operator with a tall antenna tower in his back yard. I could hear the chatter through my old Kenwood AVR on occasion. The house was a rental so he eventually moved away.

There are two issues here, which have totally different physics as to causation.

One is electro magnetic induction and the other is Radio Frequency interference.

In the OPs situation, EM is likely to be the far bigger problem.

RF interference from ham radios and commercial AM transmitter is a totally different problem.

RF interference in audio systems, is almost always picked up in the loudspeaker leads and fed back to the high gain circuits through the negative feedback. The solution for that type of RF is to find the frequency of the offending transmitter and design a resonant rejector circuit for the +ve speaker leads of each speaker right at the speaker terminal of the amp or receiver. I have used this successfully on several occasions, including for a member on these forums. I designed built, and sent him the blocking devices.

It worked well for him.

For some reason people have difficulty understanding EMI from RFI and I have trouble understanding that, as the causation and physics of the situation are poles apart.