Direct Connection: Street Lighting, LV and Telecoms

0:06A utility detection survey should always be started with a Genny looking for known services. A voltstick is used prior to touching any metallic street furniture, mains or services in the excavation area. It is recommended to locate street lighting first by connecting onto the metal column. This technique has the potential to save time as in some situations the street lighting is connected to the LV main and by applying a signal to the lighting cable we may be able to locate the LV main and even the LV services to nearby properties. You must remember though that if the street lighting is in a loop-in loop-out system which is separate to the main LV

0:46network then only the street lighting circuit will be located and more work must be done. It is important to note that modern housing using the PME system can often lack a physical ground at the property, making it very difficult for a Genny signal to travel from the main to the house. In this instance, a connection to the property should be made to allow the signal to travel back to the main. When tracing a street light cable, ensure you place the earth pin very close to the column. This will allow the Genny and its leads to remain in close proximity and in turn allow us to work

1:21as close to the column with the CAT as possible. The earth pin can be put into the ground at a shallow angle to minimize any contact with underground services. If there is no soft ground available, water can be used as an earth. With the Genny turned on, connect one lead to the earth pin. Connect the other to the column. A change in tone should indicate that a good circuit has been made. If you find it difficult to get a connection to the column, i.e. a concrete column, a capacitance technique can be used by wrapping the cable around the column. Please note when using capacitance techniques, there is no tone

2:02change from the Genny. At this point, the Genny can be muted by turning it off and then pressing and holding the button. Before we locate the lighting cable, we should disable the strike alert feature to avoid getting confused by any false alarms. To do this, press and hold the button on top before you squeeze the trigger. Start around 2 m from the column and keeping the CAT still at the side of your body, perform a series of circles or semicircles around the column to localize the signal. Once you've localized the signal, narrow down the sensitivity control to pinpoint. Rotate the CAT through 90° and align the CAT to the maximum signal

2:46level. The cable is now at 90° to the cat. The cable can now be followed and traced. It is important to follow the signal and note any sudden change. For example, a sudden loss of signal over a short space usually indicates a branch has come up the line. You have passed over the joint. Depth estimation can now be performed. The reading from the CAT is distance. Therefore, if the CAT is not directly above the cable, but off to one side, the reading will be greater than the actual depth. It is vital to ensure the cat is directly above the cable. Do not take a depth estimate near a bend

3:29or T junction or in the presence of multiple Genny signals. Take a depth reading by pressing and releasing the button. This reading must now be tested for reliability by raising the CAT a known height and repeating the reading we should now have increased by the amount raised. Note holding the button rather than releasing will perform the sonde depth. And when this is done using the Genny, the reading will be incorrect. Once the street lighting has been detected and marked, we now need to use the Genny to locate the remaining LV network, both the mains and the LV services. To apply a Genny signal to this network,

4:13it is best to utilize the crossbonding system in domestic properties. We can connect to gas meters, gas risers, metal boiler flue, metal outside light, boiler blow-off, or an outside tap. Capacitance methods can also be used here. For example, by wrapping the lead around a plastic light fitting. All of these will usually connect to the LV service in the property and allow a Genny signal to be sent down the LV service and also along the LV main. Multiple connections to multiple properties may be needed to locate the whole LV network. It is essential that the LV network is located using the Genny before any excavation work commences. To locate an LV service,

4:55it is preferred to apply the signal to the property. This allows a 100% signal on the LV service. This signal is then split as it joins the LV main, usually traveling in both directions along it. With a greater signal on the LV service than the main, the location of the service is easy to establish. When applying a Genny signal to the main LV rather than the house, the greater signal is often on the LV main, making it more difficult to locate the LV service. For multiple LV mains, we now need to refer to our utility plans. This will allow us to see where the best

5:32place to apply the Genny signal is. Look out for locations on the plan where you could apply the Genny signal to individual cables and allow signal cables to be located one at a time in an otherwise congested area. With the LV network now located and marked, we can move on to the location of communications cables. Using the signal clamp to amplify a signal directly onto communications cables is the preferred method.