Considering about Lightning Protection of a system, there are 2 major types we can mainly discuss, Direct Lightning Protection and Indirect Lightning Protection.When designing Direct Lightning Protection system, as the conducting path we mostly use copper strips, copper rods, and sometimes copper plates when we have to minimize resistance, where there is a limited space to work with. Any way in this post I am not going to discuss about Lightning protection system, but a way to calculate price for copper, without being disguised from the suppliers.
In telecommunication systems for the protection of the tower, some operators use copper strips as the down conductor, some don’t use any conductor but the tower it self as a down conductor. Anyway for the grounding of the cabin, and to make the common ring, we have to use copper strips, mostly in telecommunications industry we use 25 mm x 3 mm copper strips.So the project price for grounding Telecommunications site majorly depends on the price of copper tape, so having a knowledge how to calculate price of copper will be advantageous.
Price of metal is controlled by LME ( London Metal Exchange ) like OPEC for Oil, you can see the price now from this site http://www.lme.com/metals/non-ferrous/copper/.So for this calculation i will use the maximum price for the safe margin.
So the maximum price for 1 tone of copper is 4690 USD. This mode of copper should be formed in to copper strips,so the price should be multiplied by forming factor.When copper strips are made, it should be delivered to a country, if I get a example to Sri Lanka,we have to pay freight(either air or sea) and insurance. All together the cost price is known as CIF Price.
CIF price for cu 1 ton = 4690USD*forming factor +freight price+Insurance price
lets take all factors as 1.5 ( A valid reasonable factor when delivering Sri Lanka)
- CIF Price 1 ton copper =4690*145(Exchange rate USD to LKR)*1.5=1,020,075 LKR
In this example lets take a 25 mm x 3 mm copper tape, the volume of the tape for 1m is
- Volume of strip =2.5 cm x 0.3 cm x 100 cm =75 cm3
- Density of copper =8.92 gcm -3
- Weight of 1 m copper tape =8.92 x 7 = 669 g
So 1 m copper tape weighs about 669 grams, so we can calculate cost for 1m copper tape
Cost for Copper tape =(1,020,075 LKR x 0.669)/1000 =713 LKR
Actually this cost is before adding customs duty, the customs added price can be calculated from HS code normally any country has it’s own duty potions, in Sri Lanka can be viewed here . So for copper it’s about 15% custom duty.
Cost price after adding duty=713 x 1.15 = 819.98 LKR
So for the cost price when importing 1 m copper tape is around 820LKR, so then the supplier ads their profit margin for it.So next time when you getting a price from a supplier for copper tape, remember this, weather they have given you a high price or a reasonable price…