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As stockists of Marconite, we’re able to supply the conductive concrete and pre-mix with short lead times and with no minimum order quantity, to celebrate this, we’ve decided to look at the history of Marconite Conductive Concrete, where it comes from and why it was developed.

Conductive clay such as bentonite has been used for electrical earthing for decades, however as technology and needs have increased, the demand for a more permanent earthing compound arose.

Formulating an earthing material from purposely manufactured synthetic material, that provided lower resistivity, higher strength and lower maintenance than traditional Bentonite clay, was required. The mixtures comes under many guises: conductive concrete, admix and pre-mix, but one of the resounding industry names is Marconite.

For an inside look, we’ve invited Dave Wilson from the James Durrans Group to talk about Marconite’s history and how the Marconi Company developed this effective earthing product.

In the 1960’s the Marconi Company were at the forefront of the worlds’ communication and defence sectors. Designing highly sensitive electronic systems, their engineers increasingly encountered requirements beyond the technology of the time. Marconi realised that to overcome these issues that they would need an entirely new and highly conductive method of electrically earthing installations.

From inception, this new method needed to be permanent, required no maintenance, must be chemically inert, capable of forming strong structures and could be used anywhere, even in difficult ground conditions. In 1973 Marconi’s research, combined with process engineering skills from the James Durrans Group, culminated in the product named Marconite^®.

From concept, Marconite^® has been solely manufactured from unique raw materials and to a specific process, at their Scunthorpe works. The resulting product is a true semi conducting material that does not need water in order to conduct electricity. When used as an aggregate replacement and mixed with cement it forms a conductive concrete that can be used to encase earthing systems significantly magnifying their effect.

Aside from electrical earthing, resulting from its exceptional electrical properties, Marconite^® has been widely used as an antic-static flooring system. If made into solid block, when assembled into buildings they act as a Faraday Cage, protecting the sensitive electronic equipment housed within from EMP radiation. Finally, if used in its dry granular state, it can be placed in trenches or beds to enhance existing ground conditions, a process known as soil enrichment.

Today, over 40 years since its inception, Marconite remains the industry default and standard to which all others are benchmarked. Its’ continued use around the world are testament to the vision of its original development and to the longevity of its abilities.

In the past year within the UK it forms an essential part in the latest high speed broadband networks, is extensively used in the latest power generation plants and provides rail engineers maintenance free earthing solutions. Whilst across the world it has been used in mass transit systems in Malaysia, solar power farms in the Middle East and as an essential component of national defence systems.

Diagram of Marconite installation:

As Marconite stockists and distributors, please contact our Sales Team with your earthing requirements.

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When identifying products, you may see terms such as “suitable for outdoor use” and “weatherproof”. It is important to be careful when selecting products that claim these properties, and to establish to what “weatherproof” actually means.

Bearing in mind that we live in temperate conditions and climates vary throughout the world, just look at Britain’s weather in the past 18 months; drought last winter, followed by the second wettest calendar year, sub-zero snow-storms bringing the country to a standstill and so far a summer which is only just rearing its head. With such unpredictable weather within the UK, you can understand why weatherproof can mean different things in different parts of the world, to different manufacturers.

Flexicon’s technical director, Ian Gibson, warns that before specifying outdoor protection, make sure you clearly define exactly what it is you require. With such a wide scope of local climates, manufacturers should have a wide range of products to choose from. Flexicon, for instance, has 48 different flexible conduit systems with hundreds of variations when it comes to terminations.

There are a number of factors that should be considered when evaluating the true level of weather-proofing a product possesses. IP ratings are considered a primary factor but this should not be the only factor considered.

IP Ratings

The first number on a product’s ingress protection rating describes its resistance to solids and dust, the second number represents the protection against water and moisture ingress.

It’s important to remember the IP rating of a termination product, such as a cable or conduit gland, usually refers to the outer seal and an extra washer may be required to achieve the same IP rating on the equipment or enclosure entry. More information can be found here.

Ian recommends, when considering flexible conduits, the conduit should have a minimum of IP6x when it comes to dust ingress, regardless of the conduit’s application.

The different levels of ingress protection are outlined in the chart below.

1st Digit (Solid Objects)			2nd Digit (Water and Moisture)
#	Explanation		#	Explanation
0		Non-Protected	0		Non-Protected
1		Protected against solid foreign objects of 50mm diameter and greater	1		Protected against drops of water falling vertically
2		Protected against solid foreign objects of 12.5mm diameter and greater	2		Protected against drips of water falling up to 15o from the vertical
3		Protected against solid foreign objects of 2.5mm diameter and greater	3		Protected against spraying water at up to 60o from the vertical
4		Protected against solid foreign objects of 1.0mm diameter and greater	4		Protected against splashing water from all directions
5		Dust-protected	5		Protected against jet of water from all directions
6		Dust-tight	6		Protected against jet of water similar for to heavy seas
			7		Protected against the effects of immersion
			8		Protected against prolonged effects of immersion under pressure to a specified depth.
			9K		Steam clean, high pressure temp jet wash to DIN40050

When considering what moisture ingress protection is required, it is recommended to take a ‘belt and braces’ approach to prevent water ingress over longer periods of time. Therefore, a rating of IPX6 or IPX7 should be specified, unless the fitting is suitably sheltered, such as on the underside of an enclosure.

Ultraviolet Degradation

The amount of UV radiation that a product is exposed to will depend on location, altitude and climate. The ultraviolet rays will affect the performance of plastic materials by breaking down the long polymer chains, reducing the impact strength, flexibility and working life of the product.

Although other coloured plastics can be manufactured to be UV resistant, Flexicon predominately offer black plastics as the carbon black within them helps protect the polymer chains.

Corrosion

Corrosion becomes an issue if metal conduits and fittings are used. Coated steel is preferred, as long as its IP rating is sufficient to prevent water entering the conduit.

Nickel-plated brass fittings will discolour through oxidisation over time, especially in coastal areas. Grade 316 stainless steel is recommended for use in marine environments.

Temperature

When considering temperature, generally the maximum temperature reached naturally by the weather will not present an issue with most products. Colder temperatures can cause more of a problem; you should consider the potential hazards to which a product might be exposed, to prevent failure during operation or installation.

Flexicon understand the need to have products that fit the harsh and sometimes unpredictable climates around the world. Their LTP flexible conduits, when used with stainless steel fittings, represents an all-round “weatherproof” product, with an IP rating up to IP69k and operating temperature ranging between -20^oC to 105^oC. The LTPHC range extends this temperature range to -60^oC to 150^oC.

Ian Gibson, technical director at Flexicon is also the chairman of both the IEC (Worldwide) and CENELEC (European) committees that prepare conduit standards.

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