同時，字跡必須(xu)清晰，不(bu)易擦(ca)掉。3。試(shi)彎曲。可取一根(gen)電線電纜頭用手反復彎曲，凡是手感柔軟、抗(kang)1疲勞強度好(hao)、塑(su)料或橡膠手感彈性大(da)且電線絕(jue)緣體上(shang)無(wu)龜裂的就是優等品。電線絕(jue)緣層看上(shang)去(qu)好(hao)像很(hen)厚實，實際上(shang)大(da)多是用再生塑(su)料制成(cheng)的，只要稍用力(li)擠壓，擠壓處(chu)會(hui)成(cheng)白色狀，彎曲4～6次就有斷(duan)線現象；4。撕絕(jue)緣。的絕(jue)緣料都有一定的機械強度和(he)柔性，輕(qing)易撕不(bu)開的。

電(dian)(dian)(dian)線(xian)(xian)(xian)(xian)電(dian)(dian)(dian)纜的(de)(de)銅(tong)導(dao)(dao)線(xian)(xian)(xian)(xian)應該使(shi)(shi)(shi)用高(gao)純(chun)度電(dian)(dian)(dian)解銅(tong)，這(zhe)樣的(de)(de)材(cai)(cai)料拉(la)出來的(de)(de)絲均(jun)勻且(qie)有(you)光澤。有(you)些生(sheng)(sheng)(sheng)產企業(ye)為獲取高(gao)額利(li)潤(run)使(shi)(shi)(shi)用再生(sheng)(sheng)(sheng)銅(tong)，或偷工(gong)減料減少銅(tong)線(xian)(xian)(xian)(xian)面積，導(dao)(dao)致電(dian)(dian)(dian)線(xian)(xian)(xian)(xian)的(de)(de)導(dao)(dao)體電(dian)(dian)(dian)阻嚴重超標，導(dao)(dao)線(xian)(xian)(xian)(xian)載(zai)流量(liang)大打折扣，使(shi)(shi)(shi)用時導(dao)(dao)體過(guo)熱，影(ying)響了(le)電(dian)(dian)(dian)線(xian)(xian)(xian)(xian)的(de)(de)使(shi)(shi)(shi)用壽(shou)命，產生(sheng)(sheng)(sheng)安(an)全隱患。二、絕(jue)(jue)緣和護(hu)套(tao)材(cai)(cai)料的(de)(de)機械(xie)性能（抗(kang)張強度、斷裂伸(shen)長(chang)率）指標不合(he)格。部分(fen)電(dian)(dian)(dian)線(xian)(xian)(xian)(xian)電(dian)(dian)(dian)纜的(de)(de)絕(jue)(jue)緣和護(hu)套(tao)材(cai)(cai)料使(shi)(shi)(shi)用再生(sheng)(sheng)(sheng)塑料，其抗(kang)張強度和斷裂伸(shen)長(chang)率無法達到使(shi)(shi)(shi)用要求。這(zhe)種(zhong)電(dian)(dian)(dian)纜在(zai)受力過(guo)程中易(yi)斷裂，致使(shi)(shi)(shi)帶電(dian)(dian)(dian)導(dao)(dao)體裸(luo)1露，造成(cheng)短(duan)(duan)路(lu)和漏放電(dian)(dian)(dian)。三(san)、高(gao)壓電(dian)(dian)(dian)纜絕(jue)(jue)緣熱延伸(shen)項(xiang)目(mu)不合(he)格。個(ge)別產品的(de)(de)絕(jue)(jue)緣熱延伸(shen)出現(xian)(xian)了(le)熔斷現(xian)(xian)象，在(zai)高(gao)溫(wen)情況下易(yi)造成(cheng)短(duan)(duan)路(lu)事故(gu)。

電(dian)(dian)線電(dian)(dian)纜(lan)因導(dao)(dao)線過(guo)載而(er)起火(huo)的(de)(de)原因。過(guo)載使(shi)(shi)(shi)雙股(gu)(gu)導(dao)(dao)線間(jian)絕緣(yuan)層破壞引(yin)起短路，燒(shao)毀設備，引(yin)發(fa)火(huo)災(zai)。雙股(gu)(gu)導(dao)(dao)線靠其間(jian)絕緣(yuan)層隔開，過(guo)載使(shi)(shi)(shi)絕緣(yuan)層軟化(hua)破壞，從而(er)導(dao)(dao)致兩股(gu)(gu)導(dao)(dao)線直接(jie)接(jie)觸引(yin)起短路，燒(shao)損設備。同時短路瞬間(jian)大電(dian)(dian)流1產生的(de)(de)高溫(wen)使(shi)(shi)(shi)線路起火(huo)、熔(rong)斷，產生的(de)(de)熔(rong)珠落至可(ke)燃(ran)(ran)物引(yin)發(fa)火(huo)災(zai)。過(guo)載溫(wen)升(sheng)還能直接(jie)引(yin)燃(ran)(ran)附(fu)近(jin)可(ke)燃(ran)(ran)物。過(guo)載導(dao)(dao)線傳熱使(shi)(shi)(shi)附(fu)近(jin)可(ke)燃(ran)(ran)物溫(wen)度升(sheng)高，對(dui)附(fu)近(jin)燃(ran)(ran)點(dian)較(jiao)低的(de)(de)可(ke)燃(ran)(ran)物來講，將其引(yin)燃(ran)(ran)造成(cheng)火(huo)災(zai)是有可(ke)能的(de)(de)。在貯存物品(pin)的(de)(de)庫房和使(shi)(shi)(shi)用(yong)易、可(ke)燃(ran)(ran)裝修的(de)(de)建筑中，這種危險(xian)性尤為突出。過(guo)載還使(shi)(shi)(shi)線路中的(de)(de)連(lian)接(jie)處在過(guo)熱的(de)(de)條件(jian)下(xia)，這加(jia)速了其氧化(hua)的(de)(de)過(guo)程。氧化(hua)使(shi)(shi)(shi)連(lian)接(jie)點(dian)處產生不易導(dao)(dao)電(dian)(dian)的(de)(de)薄薄一層氧化(hua)膜，綠(lv)寶礦用(yong)電(dian)(dian)纜(lan)，氧化(hua)膜加(jia)大了接(jie)觸點(dian)間(jian)的(de)(de)電(dian)(dian)阻，從而(er)產生打火(huo)等(deng)現象，引(yin)起火(huo)災(zai)。