Last month, I purchased the Brother HL-L2400DW Laser Printer for just $159 (AUD), and it turned out to be a fantastic find for those concerned about EMF exposure. Unlike many other printers, this one has a functional Wi-Fi on/off button, allowing users to disable wireless signals completely when not needed.
Even better, when I connect my ungrounded MacBook to a power outlet while using this printer, the MacBook becomes grounded, significantly reducing dirty electricity and electric fields. This means electric field readings drop from 30 V/m to 1 V/m in a potential-free measurement and from 300+ V/m down to 10-15 V/m with body potential. For those working with plugged-in MacBooks older than 2016, grounding is essential.
Avoiding Ground Loops for Cleaner EMF Levels
One crucial thing to remember when using a grounded printer or monitor with a MacBook is to avoid having multiple grounded devices plugged into the same MacBook. This is where ground loops can occur, causing high electric field levels due to looping currents. People using grounded ethernet cable kits often unknowingly create ground loops, as they may not be aware of how electronic grounding works.
To prevent ground loops, it’s essential to ensure that only one grounded connection is used, whether it’s the printer, monitor, or a properly configured grounding kit. Many people don’t actually need a separate grounding kit, as most offices already have three potential grounding sources: a printer, a grounded ethernet switch, or a grounded monitor.
How to Check If Your Devices Are Grounded
Wondering if your device is grounded? It’s simple:
Two-prong plug = Not grounded
Three-prong plug = Grounded
Q: My iMac electric fields go up on my iMac when I plug my grounded printer in. A: The new iMacs use a three-prong setup. I often find that people have grounded printers positioned a few meters away from their main screen and laptop setup—usually 3 to 5 meters. As a result, the monitor or iMac ends up plugged into a different power point or circuit, causing a loss of ground continuity.
To fix this, try plugging the printer into the same power point or power board. Alternatively, you could remove the ground prong on the printer, as we are dealing with a permanent setup—but that’s a bit of a gray area.