Hotline Washing and Maintenance

Vice President: Mr. E.B. Gole




Hotline Washing / Maintenance:

The method and equipment used for Hotline Washing was developed by Yashmun, and has been in use internationally for the last two and a half decades.

This process entails cleaning of Insulators and Switchyards under live line conditions



The enormous growth of industries has caused a considerable growth in atmospheric pollution in the form of dust, coal dust, ash and chemicals in industrial areas. Along with contributing geographical factors such as proximity of coastal areas, salt deposits, smog, rain etc. serious damage and maintenance problems are caused for power generating units.

Despite the different anti pollution measures and devices the Government requires industries to install,contamination is an ever increasing problem in the power industry. The pollution in form of conducting materials affects the Insulators and hardware in switchyards, as well as on overhead Transmission lines.

The pollution build up on these transmission lines provide a conducting path, resulting in flashover, that in turn cause power disruptions to industries affecting production.

To arrest such contamination of Insulators, it is necessary to have a regular program of cleaning at regular intervals. The earlier solution to the problem was to de-energize the line or Sub-station and have workmen climb up and clean the Insulators in a tried and proven method of “hand rub”, which entails physical manual cleaning. In today’s ever increasing demand for electrical energy this process proves to be un-economical as the power industry does not make money unless electricity is flowing.

This is where the process of Hotline Washing proves invaluable, as there is no need for power shut downs and has proved to be a safer in a more economical way.

This method developed by us at Yashmun is now extensively being used for washing almost all Electricity Boards and Electric Undertakings in India.

Operating Principles:

Whenever a jet of water is released in the air, the water particles split due to resistance. At a sufficient distance the jet moves in the form of small particles separated by air ,and the water path is not continuous. This forms a product similar to an aerosol, which in turn guarantees a sufficient electrical resensitivity, hence there is no leakage current . This is the principle behind the Yashmun method of Hotline Washing.

The high pressure jet is produced by means of a pump. Water with conductivity of 200 micromhos or less per cc is used for washing purposes up to 220 KV. Hence normal lake or river water or treated municipal water that has a conductivity of 90 to 120 micromhos can be used. In the case of 400 KV washing only by D.M water is recommended.

The specilised nozzle used is held at a distance stipulated from the live point so that no leakage current is encountered. For safety, leakage current in the water jet and nozzle is continuously monitored by means of a special detector, designed and made by Yashmun.

Electrically Operated Equipment:

This is operated by a 415V, 3PH, motor. The unit consists of a motor driven high pressure pump with a starter flexible hoses and HP nozzles. All this is mounted on a trolley. A 2000 ltr water tank is placed on another trolley .The complete washing equipment is mobile and can be taken anywhere in the Switch yard or Tower location.

Truck Engine Operated Equipment:

This equipment developed by Yashmun is used in instances where no power is available and is fully mobile, especially through hilly /jungle areas where Transmission lines pass. This equipment has been developed for the washing of Transmission line towers up to 400KV.In this equipment, the high pressure pump is operated by means of Power-Take-Off shaft (PTO). The Truck is provided with 5000 ltr of D.M or raw water. As the equipment is operated by means of the trucks engine there is no need for electricity.

  • No shut down/outages required
  • Time and money saved as Power generation and Transmission are not disrupted while the job is done.
  • Improves the di-electric strength of Insulators
  • Increases the life of Insulators
  • Reduces transmission loss
  • Helps Switchyard / Transmission lines function smoothly



We, at Yashmun, undertake Hot/Live line maintenance jobs upto 220 KV. We have all the required tools and instruments imported from RITZ Brazil and A.B.Chance USA. Our certified engineers and technicians have undergone training at the National Power Training Institute in Bangalore.


Due to the increasing complexity of transmission networks, coupled with inter regional /inter State ties, transporting of large quantum’s of power has rendered shut-downs on Transmission lines/stations almost impossible, thus rendering a need for live wire maintenance technicians. A network of 220 KV and 400KV Transmission lines form the backbone of the Transmission network. Power flow from these networks are monitored and regulated by National / Regional / State load dispatch centers. It is obvious that a constant supply of electricity is required by consumers and for this an almost un- interrupted stable availability of Transmission lines is required. Providing redundancy in transmission lines could be a solution, which, however is a costly option. Therefore preventive maintenance, deploying live line maintenance techniques, proves the best solution.


When testing a string of Insulators, each Insulator is consecutively brought in shunt contact with the testing instrument prong and the meter deflection is observed. Any sudden dip in the meter deflection across an Insulator determines the Insulator is faulty and signifies replacement.

To carry out this test we use an indicating instrument with 2 prongs in association with a hot stick . Current passing through an Insulator is proportional to the voltage absorbed by that Insulator.