![EMI/RFI considerations](/images/new-backgrounds/54756/54756115x1.webp)
Chapter 4 Installing the Tracer Summit BMTX BCU
EMI/RFI considerations
Take care to isolate HVAC controllers from electromagnetic interference (EMI) and radio frequency interference (RFI). Such interference can be caused by radio and TV towers, hospital diagnostic equipment, radar equipment, electric power transmission equipment, and so on. In addi- tion, take care to prevent the BMTX BCU from radiating EMI and/or RFI.
The BMTX BCU is equipped with EMI/RFI filters that trap RFI to ground. In most situations, a good earth ground will reduce EMI/RFI problems by acting as a drain for EMI and RFI. If the BMTX BCU is receiving or radiating interference, make sure that the earth ground is good. Do not assume that the building conduit is an adequate ground.
Checking the earth ground
Though a proper earth ground is especially important in areas of high EMI or RFI, always check the quality of the ground, regardless of location.
WARNING
Hazardous voltage!
The cover plate must be in place when the BCU is operating. Failure to replace the cover plate could result in death or serious injury.
If the earth ground has a voltage of more than 4 Vac, use a different ground. Failure to do so could result in death or serious injury.
To check the quality of the earth ground:
1.Open the enclosure door.
2.Inside of the enclosure at the
3.Measure the ac voltage between the earth ground and the neutral ter- minal, as shown in Figure 20 on page 47.
Ideally, the voltage should be 0 Vac. Find a different ground if the voltage exceeds 4 Vac. A higher voltage may result in:
•Danger to people touching the enclosure
•Erratic communications
•Erratic equipment operation (Because noise may affect voltage levels at the
4.Replace the cover plate.
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