| 1. |
Lightning is a natural phenomenon which develops when the upper atmosphere becomes unstable due to the convergence of a __________, vertical air column on the cooler upper air mass. |
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Warm, solar heated |
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Cold and frigid |
| 2. |
These rising air currents carry water vapor which, on meeting the cooler air, usually condense, giving rise to convective storm activity. |
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True |
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False |
| 3. |
To be capable of generating lightning, the cloud needs to be 3 to 4 km deep. The _______ the cloud, the more frequent the lightning. |
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Shorter |
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Taller |
| 4. |
Lightning can also be produced by frontal storms where a front of cold air moves towards a mass of moist ____________. |
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Warm air |
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Cold air |
| 5. |
For lightning protection, we are mainly concerned about the cloud-to-ground discharge. This is a two-staged process, with one process being initiated from the cloud, while the second is initiated from ________________. |
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The ground or structure |
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Cold air moving in |
| 6. |
Once the ionized channel has been completed by the junction of the upward and downward leaders, a low impedance path between the cloud and ground exists and the main stroke commences. This is characterized by a rapidly increasing electric current whose rate of rise is typically 10 kA/μs. Peak currents averaging around 30 kA are typical, with minimum currents being a few kA. Maximum lightning currents exceeding 200 kA have been recorded. |
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True |
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False |
| 7. |
No lightning protection system is 100% effective. A system designed in compliance with the standard does not guarantee immunity from damage. Lightning protection is an issue of statistical probabilities and risk management. A system designed in compliance with the standard should ________________________________ |
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Statistically reduce the risk to below a pre-determined threshold. |
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Should increase the risk of lightning. |
| 8. |
Which one of the following protection systems should be included in a new design. |
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Intercept lightning flash (i.e. create a preferred point of strike) |
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Conduct the lightning current to earth |
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Dissipate current into the earth |
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All of the above |
| 9. |
Which one of the following protection systems should be included in a new design. |
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Create an equipotential bond to prevent hazardous potential differences between LPS, structure and internal elements/circuits |
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Not cause thermal or mechanical damage to the structure |
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All of the above |
| 10. |
Which one of the following protection systems should be included in a new design. |
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Not cause sparking which may cause fire or explosion |
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Limit step and touch voltages to control the risk of injury |
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to occupants |
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Limit damage to internal electrical and electronic systems |
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All of the above |
| 11. |
Lightning protection systems typically follow two approaches:
Non-isolated system – where potentially damaging voltage differentials are limited by bonding the lightning protection system to the structure
Isolated system – where the lightning protection system is isolated from the structure by a specified separation distance.
This distance should be sufficient that energy is contained on the LPS and does not spark to the structure. Isolated systems are well suited to structures with combustible materials such as thatched roofs, or telecommunication sites that want to avoid lightning currents being conducted on masts and antenna bodies |
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True |
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False |
| 12. |
Figure 14, describes: |
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Lightning protection design process |
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Project coordinator’s task box |
| 13. |
Aluminum has the advantage of lower cost. Its lighter weight is also a benefit to the installer. However, aluminum is less compatible with many building materials and can not be buried in the ground. Therefore, most lightning protection systems are entirely copper or utilize an upper aluminum portion connecting to a copper earth termination system. As aluminum and copper ________________, a bimetallic joint should be used to interconnect these two materials. |
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Are not compatible |
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Are compatible |
| 14. |
Figure 16 shows: |
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Bimetallic and stainless-steel connectors |
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Battery governor connectors |
| 15. |
It ______________ to bring all services into the structure in close proximity to each other to simplify the bonding requirements, and to minimize voltage differentials between each service. This is especially important for the protection of sensitive equipment such as computers and communication equipment which may interconnect to both services. |
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Is good practice |
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Is not good practice |
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