降低building 既earth loop impedance.

降低"現有"及"新建"建築物既 Earth loop impedance 方法如下

現有建築物可以用降阻劑，降阻劑由多種成份組成，其中含有細石墨、膨潤土、固化劑、潤滑劑、導電水泥等。它是一種良好的導電體，將它使用于接地體和土壤之間，一方面能夠與金屬接地體緊密接觸，形成足夠大的電流流通面；另一方面它能向周圍土壤滲透，降低周圍土壤電阻率，在接地體周圍形成一個變化平緩的低電阻區域，但係需要保養，每隔兩年要檢查。

新建建築物可以將接地導體接去地基，先將四周地基既鐵條焊一條導體出來，然後再將每一條導體用銅帶連接在一齊，最後接去個需要接地既物件，呢D就係最好既水線，每隔十年檢查一次。



接下來，如果係電既Earth loop impedance，你可以用TN接地系統，TN有兩種接法，一種係TN-C(combine)，即係中線就係接地既水線同一導綫，另一種係TN-S(separate)，即係中線同接地既水線分開用另一導綫，將電源中線接地個位置接過來，更有一種叫TN-C-S，即係TN-C同TN-S聯合起來，電流大既就要用呢種接地法。



參考下圖 ：


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l. - the phase conductor from the transformer to the installation

2. - the protective device(s) in the installation

3. - the installation phase conductors from the intake position to the fault

4. - the fault itself (usually assumed to have zero impedance)

5. - the protective conductor system

6. - the main earthing terminal

7. - the earthing conductor

8. - the installation earth electrode

9. - the general mass of earth

10. - the Supply Company's earth electrode

11. - the Supply Company's earthing conductor

12. - the secondary winding of the supply transformer

For a TN-S system (where the Electricity Supply Company provides an earth terminal), items 8 to 10 are replaced by the PE conductor, which usually takes the form of the armouring (and sheath if there is one) of the underground supply cable.

For a TN-C-S system (protective multiple earthing) items 8 to 11 are replaced by the combined neutral and earth conductor.

For a TN-C system (earthed concentric wiring), items 5 to 11 are replaced by the combined neutral and earth wiring of both the installation and of the supply.

It is readily apparent that the impedance of the loop will probably be a good deal higher for the TT system, where the loop includes the resistance of two earth electrodes as well as an earth path, than for the other methods where the complete loop consists of metallic conductors.