Enclosure Grounding

More Information about Enclosure Grounding

Grounding also plays a significant role in stabilizing the electrical potential of the enclosure, thus safeguarding sensitive electronics inside from static charge buildup and voltage spikes, which might occur due to lightning strikes or power surges. For metal enclosures, this is particularly important as metal is a good conductor of electricity.

In addition to grounding the enclosure itself, it's also vital to ensure that all equipment within the enclosure, such as circuit breakers, power supplies, and other electrical devices, are properly grounded. This includes tying the ground wire to the grounding conductor, which might be part of the power supply system or an independent grounding system.

One issue that can arise in grounding systems is the formation of ground loops, which occur when there is more than one grounding path between two points in an electrical system. Ground loops can cause unwanted noise or interference in electronic systems and need to be carefully managed during installation.

It's essential that enclosure grounding adheres to electrical codes and standards to ensure safety and efficacy. In some cases, such as with double insulated enclosures or those with a plastic case, grounding may not be necessary as these materials act as insulators and don't conduct electricity. However, for all metal enclosures and other enclosures where grounding is required, it is an indispensable safety measure.

FAQs

What is a good equipment grounding conductor for an electrical enclosure?

A good equipment grounding conductor for an electrical enclosure is typically a copper wire or copper alloy wire. Copper is a preferred material due to its excellent electrical conductivity and durability. The size of the copper grounding conductor should be appropriate to the electrical load and in compliance with local electrical codes and standards.

Grounding in a Control Panel

All devices and signals within a panel should be tied back to one single location.

It is common to see several different devices within a control panel that need to be grounded. No matter the number of devices, it is essential to ensure that everything comes together in one location. This location is where the main utility power and grounding conductor  enters the panel. It can also be where the enclosure is grounded to an exterior ground rod. Tying everything to the utility ground or ground rod, allows any short circuits and surges to be dissipated out of the control panel, protecting sensitive equipment. It can also help to reduce any chances of creating ground loops within the enclosure.

Analog signal grounding.

Typically, analog signals have shielded wire to protect the signal from “noise” or distortion that could potentially corrupt the signal.  This shielding needs to be grounded in order to dissipate that “noise”. It is important to know that this shielding should only be grounded at one location along the circuit, typically within the control panel where the conductors are being terminated, and not on the field side of the device. If both ends of the shielding are terminated, it can cause issues with the signals as well as create potential ground loops.  

AC and DC circuit grounding.

In some cases, it is necessary to isolate the AC ground from the DC ground, but in the case of most industrial control panels it is common to see these two types of power share a “common ground”. This is done by tying the DC negative portion of the DC bus to the AC ground bus within the control panel. This allows everything, including all AC and DC circuits, to be tied back to one single location within the panel. 

Outdoor enclosure grounding.

When an industrial control panel is being installed in an outdoor location, or anywhere that it might be exposed to the elements, it is critical to install a ground rod and ensure that the enclosure is tied to that ground rod. In the event of a lighting strike, the ground rod will allow the bulk of that energy to be dissipated directly into the ground, while protecting the hardware within the panel.