Grounding Essentials · Best Grounding Techniques When Building A Home In Mexico · Yucatan & Riviera Maya

Proper grounding is always emphasized when talking about domestic electrical installations and it represents one of the major checkpoints on the home inspector's list. For a good reason: it is essential for our protection, as well as the safety of our electric and electronic equipment.

We can observe four situations when good ground can make a difference:

1. LIGHTING

Never forget the Mexican Caribbean is prone to extreme weather, intense storms can literally form out of the blue.

2. STATIC ELECTRICITY


3. ELECTRICAL FAILURE


4. TRANSIENT OVER-CURRENTS

Transient surges are defined as momentary bursts of energy in a system caused by an internal event (i.e. powering on or off) or a nearby event (i.e. lightning).

Grounding Benefits

The fundamental objectives of the grounding systems are as follows:

• To ensure personal safety
• To protect electric equipment and to ensure correct functioning of protection devices
• To stabilize voltage by establishing a reference potential:
  

  For measurement purposes, the Earth serves as a potential reference against which other potentials can be measured. An electrical ground system should have an appropriate current-carrying capability to serve as an adequate zero-voltage reference level. In electronic circuit theory, a "ground" is usually idealized as an infinite source or sink for charge, which can absorb an unlimited amount of current without changing its potential. Where a real ground connection has a significant resistance, the approximation of zero potential is no longer valid. Stray voltages or earth potential rise effects will occur, which may create noise in signals or if large enough will produce an electric shock hazard. Wikipedia

• To allow lighting energy to flow into ground
• To limit transient over-currents
• To drain static energy

Grounding Techniques

The common method of domestic grounding is a metallic copper protected rod driven into the ground. Natural electrodes like rebar in concrete or buried copper and galvanized water pipes can also be used. It is very uncommon though to see this type of grounding here, in the Riviera Maya, as most water connections are made using plastic pipe and most reinforced footings are sitting on top of stone masonry (they are not buried).

Grounding electrode scheme


Natural grounding connected to rebar


Natural grounding connected to copper water pipe

Resistance is extremely important when discussing ground connections. As the word itself implies, the lower the resistance, the easier electric current will flow towards the ground. The higher the resistance, the most likely electricity will try to find a different, less resistive path to ground. Good and clean connections in the grounding circuit are a must if we want to achieve minimum resistance. The NEC (National Electric Code) as well as the NOM (Norma Oficial Mexicana) recommend grounding should not exceed a resistance of 25 ohms. The soil itself plays an important role in defining resistance: marshy, slate, sandy, limestone or rocky, resistance varies greatly. Marshy grounds have a resistance of 30 ohms while rocky ground, just like what we have here in the Yucatan Peninsula, poses the greatest resistance of all 1500 to 3000 ohms! - which means it can be a very poor conductor.

What can be done to overcome this high resistance problem in our area? There are several options.

The use of ground enhancers just around the Electrode:


Ground enhancers are made of natural minerals that absorb and retain water. They don´t dissolve or decompose in time and permanently lower the earth resistance.

Using electrodes that allow more contact area:


Using Antiox:

Antiox will form a strong and flexible protective layer on all ground connections in order to protect them in a humid and salty coastal environment.Once cured it offers a dielectric resistance of 37000 Volts with a 3mm waterproof membrane

Another way of providing a safe ground in the area is to drill a well that reaches ground water (which is about 10-15 meters) and make sure your ground electrode touches water.

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