Earthing Compound - Bentonite and Marconite

AN Wallis Earthing Compound - Bentonite Compound

Low Resistance Earthing Compounds for Substations

Bentonite Compound

Marconite Compound

AN Wallis Earthing & Lightning Protection Distributors

Bentonite Compound

Bentonite is a moisture retaining clay used as an earth electrode back-fill to help lower soil resistivity. The Bentonite clay is a sodium activated montmorillonite which when mixed with water swells to many times its original volume. 

If underground power cables are required to run at maximum direct burial rating when installed in cable duct, then the cable duct should be filled with Bentonite mixture (100 parts of 10:1 Bentonite / water mix to 20 parts sand and 8 parts cement).

The Bentonite mixture should be pumped into the cable duct so totally excluding the air and on completion of the filling be sealed to prevent any escape of Bentonite mixture.

Pictured: AN Wallis EGB25 Bentonite Earthing Compound  

Wallis Earthing Compound - Bentonite Compound EGB25

Bentonite can be supplied in granular or powder form - the granular form is easier to handle as the powder can cause dust in windy conditions.

Granular Bentonite is the preferred option for filling trenches as the substance can be mixed in the trench.

Pictured: AN Wallis EBG25 Bentonite Earthing Compound Used To Fill Trenches

Wallis Earthing Compound - Bentonite Compound EGB25

AN Wallis Bentonite Compound - Product Range
Part Number Type Unit Weight Pack Quantity
EBG 25 Bentonite Granular Form 25kg 1 Bag
EBG 25P Bentonite Powder Form 25kg 1 Bag

T&D offer a full range of Wallis earthing & lightning protection.

Marconite Compound

Marconite is a granulated electrically conductive aggregate which replaces sand in mixes with cement, thereby providing electrically conductive concrete.

Electrodes (including copper earth rods) can be encased in Marconite mixture to greatly increase their surface area, lowering the resistance to earth.

Marconite benefits include low resistivity, conduction of current is electronic (not ionic), permanent and stable, increased surface area contact.

Marconite is has been approved and used by the MOD, electrical utilities, rail systems and water companies.

1. What Makes Marconite Unique?

Marconite

Other earthing materials marketed as conductive aggregatres include low grade carbonaceous by-products from other industries which include Coal, metallurgical coke, Power station clinker, Carbon Black, Bentonite and others. All of these products can be called conductive with resistivity of 5 ohms metres.

The resistivity of Marconite is in the order of .001 ohm metres. When mixed with cement the resulting Conductive Concrete is still only 0.19 ohm metres.

This is significantly lower than Bentonite for example, which has a typical resistivity of 3 ohms metre upwards.

Typically the above products can include anything between 15-20% impurities which are corrosive and will corrode earth connections resulting in the loss of the system which can prove to be very, very expensive.

Marconite has no such impurities and at PH7 is non corrosive.

Marconite is manufactured specifically for earthing, it is not a by-product.

2. Application 

Marconite and Earthing of Towers

Towers used for power distribution, lighting and communication aerials are usually supported on foundations with each leg on an individual concrete base or all legs on a reinforced concrete slab. Earthing is traditionally completed with earth electrodes using conventional earth rods or tapes.

A. Marconite conductive concrete has a resistivity of 0.1 ohm metre.

B. Marconite can be placed as a blinding layer when excavating the foundations and connected by copper tape to the tower.

C. Bore holes are not required thereby reducing drilling and copper costs.

D. By incorporating a blinding layer with the foundation block the area available is considerable when compared to a single electrode, enabling the resistance required to be achieved.

Marconite and Earthing of Substations

Substations are earthed to contain any fault current within their boundaries.

At the perimeter Bore Hole with MARCONITE is constructed all around i.e if 20Mtr Bore Hole is done - then next one will be done at 20Mtr distance. This is done all around the perimeter.

A 100mm dia bore hole with a 16mm copper rod encapsulated with Marconite has a large area of dissipation that will ground any fault current faster and more safely when compared to a 16mm dia rod.

3. Key Advantages of Marconite 

Custom designed and proven in a wide range of applications including power generation,distribution, oil, gas and rail.

Suitable for all soil conditions - Marconite can give the lowest potential to earth for a wide range of soils, including granite, sand, glacial rock and made up ground.

Cost effective - Price is not cost. Using Marconite will achieve savings in drilling, copper, maintenance and installation costs

Mechanical Strength - Where required  the “Marconite” Pre- mix provides a high mechanical strength.

Inert at PH7 - Marconite is non corrosive to steel, copper bonded rods and does not attack cement structures, important in hostile conditions.

Maintains integrity of earthing systems - Marconite encapsulation protects earthing systems in corrosive soil conditions.

  • Easy to use - Marconite is normally mixed 2 : 1 by weight with cement and will absorb 15% of its own weight of water. 
  • Fast drying - Marconite is selected to give fast drying. No sand or other aggregates are necessary.
  • Permanent - Marconite has an indefinite shelf life. When mixed with cement it retains its performance after drying, has  20 years proven experience.
  • Greater surface area contact with earth - Under certain difficult ground conditions with high resistivity such as glacial rock or granite, if compressive strength is not an issue, the Marconite and cement mix with additional water can be made into a slurry.

This will leech into the cracks and fissures greatly increasing ground contact - like an inverted tree with a large root system-helping to achieve a low resistance value.

Marconite® Conductive Concrete is a registered product of the James Durrans Group and is solely produced by their subsidiary company Carbon International Limited. T&D provide fast delivery and competitive prices for genuine Marconite brand Earthing Products.

Dave Wilson of James Durrans Group clarifies differences between Marconite and Bentonite for earthing and grounding applications. "To draw distinction between the two, our product Marconite, originally developed by the Marconi company, is specifically manufactured for grounding.

Whereas Bentonite is just a clay material that is dug out of the ground and happens to have limited moisture retaining properties.

With regards to its performance, many organisations look only to use ground enhancement materials whilst attempting to overcome problems only after work has been started.

Marconite's performance is reliable, predictable and permanent but it is not a panacea. Ground enhancement is a proven technique, its just considered by many as an unnecessary on-cost for projects until its too late and they look for cure-all miracles."

Adobe AN Wallis Bentonite - Granular & Powder Bentonite

Adobe Marconite - Safety Data Sheet

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