Application Note

Grounding Your ACENet Devices (#111)

We don't require that our customers ground ACE-RIUs and ACU2s, but they were designed to accommodate those facilities that have stringent grounding policies or requirements. The truth is, most of our customers don't ground these devices, and they don't have any problems.

But, if your ASTi devices must absolutely, positively be grounded in the most effective and efficient manner possible, follow these simple tips:

1. Use a #10 grounding ring connector to attach the grounding wire to the chassis of the device at the stud provided. This is due to the size of the stud, and not necessarily the gauge of the wire.
2. Connect that to at least 18 gauge (AWG) stranded, braided or strap wire. We don't recommend using a solid wire, because it's difficult to work with, and may break.
3. You should generally keep your grounding wire as short as possible to reduce resistance. This will most effectively dissipate the unwanted electrical charge.

A note on ground loops:

ASTi recommends that you install ACE-RIUs and ACU2S, isolated from earth ground. This practice will ensure that ground loops are eliminated, especially for radio bridge application. Ground loops can occur if an ACE-RIU and radio are connected to grounds at different potentials; this results in noise introduced into the system.

Following this guidance will improve system performance:

• Only connect the ACE-RIU to the ASTi-provided isolated power supply.
• Do not bond the ACE-RIU chassis to earth ground through any contact. Specifically: take care not to connect the ACE-RIU to earth ground when rackmounting and don't tie the ACE-RIU to earth ground using the ground lug.
• Don't connect ACE-RIU ground, Pin 5 on the A-D Channel connectors, to earth ground.

The above also applies to the ACU2, however, our experience shows that the ACE-RIU is more susceptible to ground loops then the ACU2.