電纜橋架是電氣光纜裸露在外的部分，雖然線路外部有絕緣層防護(hù)，但是由于電氣光纜均是導(dǎo)電線路，因此必須接地形成一個(gè)完好的電氣連通才算可靠。

　　Cable tray is the exposed part of electrical optical cable. Although there is insulation layer protection on the outside of the line, since electrical optical cable is a conductive line, it must be grounded to form a complete electrical connection for safety and reliability.

　　而金屬電纜橋架在生產(chǎn)時(shí)沒有做出的接地螺栓，因此在施工的時(shí)候只能利用其連接板上的螺栓來連接固定跨接接地線。電纜橋架及其連接板涂有防腐涂層，若跨接連接處的絕緣防腐涂層不干凈，將不能形成良好的電氣連接，其接觸電阻不能滿足要求，將會(huì)影響到電纜橋架跨接接地線的可靠連接和接地質(zhì)量。

　　However, the metal cable tray did not have professional grounding bolts during production, so during construction, only the bolts on its connecting plate can be used to connect and fix the grounding wire. The cable tray and its connecting plate are coated with anti-corrosion coating. If the insulation anti-corrosion coating at the cross connection is not removed completely, a good electrical connection cannot be formed, and the contact resistance cannot meet the requirements, which will affect the reliable connection and grounding quality of the cable tray's cross grounding wire.

　　《驗(yàn)收規(guī)范》規(guī)定：電纜橋架及其支架接地連接可靠，其全長(zhǎng)應(yīng)不少于2處與接地（PE）干線相連接；非鍍鋅電纜橋架間連接板的兩端跨按銅芯接地線，其小允許截面應(yīng)不小于4平方毫米；鍍鋅電纜橋架間連接板的兩端可不跨接接地線，但連接板兩端應(yīng)不少于2個(gè)有防松螺帽或防松墊圈的螺栓連接固定。這是在接地施工時(shí)的要求，目前大多數(shù)施工人員都是依據(jù)這個(gè)標(biāo)準(zhǔn)進(jìn)行施工操作。

　　According to the "Acceptance Specification", the grounding connection of cable trays and their supports should be reliable, and their total length should be connected to the grounding (PE) main line at no less than 2 points; The two ends of the connecting plate between non galvanized cable trays should be crossed with copper core grounding wires, and the minimum allowable cross-section should not be less than 4 square millimeters; The two ends of the connecting plate between galvanized cable trays may not be connected to the grounding wire, but the two ends of the connecting plate should be fixed with at least 2 bolts with anti loosening nuts or anti loosening washers. This is the minimum requirement for grounding construction, and currently most construction personnel follow this standard for construction operations.

　　但是熟悉工程的人都知道，只按照限度來接地操作是完全不夠的，在具體施工中依舊存在很多接地問題：

　　However, those familiar with engineering know that only following the minimum grounding operation is not enough, and there are still many grounding problems in specific construction:

　　（1）電纜橋架全長(zhǎng)不大于30m的，應(yīng)有不少于2處與接地干線相連接，但施工中往往只做到1處與接地干線相連接，其末端應(yīng)與接地干線相連接的要求常常被忽視；全長(zhǎng)大于30m的，由于設(shè)計(jì)未注明電纜橋架與接地干線相連接的施工要求和具體連接位置，施工中通常多2處與接地干線相連接，未能做到每隔20~30m增加1處與接地干線相連接。

　　(1) For cable trays with a total length of no more than 30m, there should be no less than 2 connections to the grounding main line. However, during construction, only 1 connection to the grounding main line is often achieved, and the requirement that the end should be connected to the grounding main line is often overlooked; For cables with a total length greater than 30m, due to the lack of construction requirements and specific connection locations for cable trays to be connected to the grounding main line in the design, there are usually no more than 2 connections to the grounding main line during construction, and it is not possible to add 1 connection to the grounding main line every 20-30 meters.

　　（2）電纜橋架跨接接地線截面由于設(shè)計(jì)不明確，施工中往往只按規(guī)范規(guī)定的小允許截面4平方毫米（銅質(zhì)質(zhì)選擇，使其截面可能不滿足要求，存在接地隱患。

　　(2) Due to unclear design, the cross section of the grounding wire for cable trays is often only allowed to be 4 square millimeters according to the minimum allowable section specified in the specifications during construction (copper material selection may not meet the requirements, which poses a grounding safety hazard).

　　（3）對(duì)于非鍍鋅電纜橋架，不少產(chǎn)品本體上沒有設(shè)置專用的接地螺栓，在施工中，往往利用連接板的螺栓，在連接板處對(duì)跨接接地線進(jìn)行連接固定。由于連接板涂有絕緣的防腐涂層，可能使跨接接地線與電纜橋架的金屬本體之間不能形成可靠的電氣連通，而此時(shí)跨接地線連接又是申接連接，當(dāng)出現(xiàn)連接板松動(dòng)、脫開等現(xiàn)象時(shí)，將會(huì)造成跨接接地線連接不牢，甚斷開，使得電纜橋架失去接地，存在接地隱患。

　　(3) For non galvanized cable trays, many products do not have dedicated grounding bolts installed on the body. During construction, the bolts of the connecting plate are often used to connect and fix the grounding wire at the connecting plate. Due to the insulation anti-corrosion coating on the connecting plate, reliable electrical connection may not be formed between the cross grounding wire and the metal body of the cable tray. At this time, the cross grounding wire connection is also a nominal connection. When the connecting plate is loose or disconnected, it will cause the cross grounding wire connection to be weak or even disconnected, resulting in the loss of grounding of the cable tray and posing a grounding safety hazard.

　　（4）電纜橋架的支架接地在施工中漏接現(xiàn)象較為普遍，而電纜橋架與支架之間也沒有連接固定，使得支架沒有可靠接地。

　　(4) The grounding of cable tray supports is commonly missed during construction, and there is no connection or fixation between cable trays and supports, resulting in unreliable grounding of the supports.

　　介于上述原因，在施工時(shí)必須采取以下措施來確保電纜橋架接地：

　　Due to the above reasons, the following measures must be taken during construction to ensure the safe grounding of cable trays:

　　（1）熟悉施工設(shè)計(jì)文件中關(guān)于接地干線設(shè)置、連接位置，以及接地干線截面、跨接接地線截面選擇等內(nèi)容。

　　(1) Familiar with the construction design documents regarding the setting and connection positions of grounding main lines, as well as the selection of grounding main line sections and cross grounding wire sections.

　　（2）接地點(diǎn)可在電氣預(yù)埋階段預(yù)留引出，以滿足電纜橋架的始端、末端及中間部位的接地要求。接地干線材質(zhì)、截面應(yīng)符合設(shè)計(jì)要求。當(dāng)設(shè)計(jì)未作要求時(shí)，可參照《驗(yàn)收規(guī)范》中保護(hù)導(dǎo)體（PE線導(dǎo)體）截面的規(guī)定選擇截面。當(dāng)接地干線采用型鋼（如扁鋼或圓鋼），其截面應(yīng)符合設(shè)計(jì)要求或按相應(yīng)電導(dǎo)值進(jìn)行換算。

　　(2) The grounding point can be reserved during the electrical pre embedding stage to meet the grounding requirements of the starting, ending, and middle parts of the cable tray. The material and cross-section of the grounding main line should meet the design requirements. When there are no requirements in the design, the cross-section of the protective conductor (PE wire conductor) can be selected according to the provisions of the "Acceptance Specification". When the grounding main line is made of steel (such as flat steel or round steel), its cross-section should meet the design requirements or be converted according to the corresponding conductivity value.

　　（3）跨接接地線應(yīng)采用銅芯軟導(dǎo)線或鍍錫銅編織線，不應(yīng)采用單股銅芯導(dǎo)線，其截面應(yīng)符合設(shè)計(jì)要求。當(dāng)設(shè)計(jì)未作要求時(shí)，跨接線允許截面應(yīng)不小于4平方毫米（銅質(zhì)）、不大于25平方毫米（銅質(zhì)）。

　　(3) The jumper grounding wire should use copper core flexible wire or tinned copper braided wire, and should not use single stranded copper core wire. Its cross-section should meet the design requirements. When not specified in the design, the allowable cross-sectional area of the jumper wire should be no less than 4 square millimeters (copper) and no more than 25 square millimeters (copper).

　　（4）跨接接地宜采用焊接在電纜橋架本體上的專用接地螺栓作為跨接接地線連接點(diǎn)，不宜采用連接板連接螺栓作為跨接接地線的連接點(diǎn)；若產(chǎn)品未帶有專用接地螺栓，而施工中用連接板的螺栓進(jìn)行跨接接地連接時(shí)，應(yīng)將跨接接地連接處的不導(dǎo)電涂層進(jìn)行處理，以保證跨接接地線的可靠電氣連通。

　　(4) Special grounding bolts welded to the cable tray body should be used as the connection point for the grounding wire, and connection plate connection bolts should not be used as the connection point for the grounding wire; If the product does not come with a dedicated grounding bolt and the bolts of the connecting plate are used for cross grounding connection during construction, the non-conductive coating at the cross grounding connection should be treated to ensure reliable electrical connection of the cross grounding wire.

　　（5）跨接接地可采用每節(jié)電纜橋架之間的跨接接地線進(jìn)行跨接連接，也可采用沿電纜橋架全長(zhǎng)敷設(shè)一根銅排或銅芯導(dǎo)線或鍍鋅型鋼（扁鋼或圓鋼）作為接地干線，每節(jié)（包括直通、彎通等等電纜橋架應(yīng)少有1處與其進(jìn)行可靠連接。連接處的連接螺栓應(yīng)配置彈簧墊圈，保證連接緊固可靠。

　　(5) Cross grounding can be achieved by using the grounding wire between each section of the cable tray for cross connection, or by laying a copper bar or copper core wire or galvanized steel (flat steel or round steel) along the entire length of the cable tray as the grounding main line. Each section (including straight through, bent through, etc.) of the cable tray should have at least one reliable connection with it. The connecting bolts at the connection should be equipped with spring washers to ensure a tight and reliable connection.

　　（6）對(duì)于鍍鋅電纜橋架可利用其鍍鋅的連接板進(jìn)行跨接，而不必采用跨接線進(jìn)行跨接，但連接板的兩端應(yīng)不少于2個(gè)有防松螺帽或防松墊圈的螺栓進(jìn)行連接固定，避免出現(xiàn)連接松動(dòng)、脫開等現(xiàn)象，保證跨接接地的可靠連接。

　　(6) For galvanized cable trays, their galvanized connecting plates can be used for bridging without the need for jumper wires. However, the two ends of the connecting plate should be fixed with at least two bolts with anti loosening nuts or washers to avoid loose or disconnected connections and ensure reliable grounding.

　　（7）支、托、吊架應(yīng)與電纜橋架可靠連接并接地，可與沿電纜橋架全長(zhǎng)敷設(shè)的一根銅排或銅芯導(dǎo)線或鍍鋅扁鋼作為PE線的接地線相連接，也可與已有接地電纜橋架進(jìn)行跨接連接，如可用銅芯軟導(dǎo)線或鍍錫銅編織線進(jìn)行跨接連接，或不少于2處用爪型螺母與電纜橋架進(jìn)行連按固定，使其與電纜橋架形成可靠的電氣連通。

　　(7) Supports, brackets, and hangers should be reliably connected to cable trays and grounded. They can be connected to a copper busbar, copper core wire, or galvanized flat steel as a PE wire laid along the entire length of the cable tray, or they can be cross connected to existing grounded cable trays. For example, copper core flexible wires or tinned copper braided wires can be used for cross connection, or at least two claw nuts can be used to connect and fix the cable tray, forming a reliable electrical connection with the cable tray.

　　建筑電氣設(shè)計(jì)和施工中，電纜橋架是要做接地的，這點(diǎn)是比較明確的，但是電纜橋架的支架是否也要做接地呢？

　　In the design and construction of building electrical systems, it is quite clear that cable trays need to be grounded. However, should the supports of cable trays also be grounded?

　　我們來看下規(guī)范是怎么要求的，依據(jù)國(guó)標(biāo)GB50169-2016《電氣裝置安裝工程接地裝置施工及驗(yàn)收規(guī)范》3.0.4條要求，電纜橋架、支架和井架必須接地。

　　Firstly, let's take a look at what the specifications require. According to Article 3.0.4 of the national standard GB50169-2016 "Code for Construction and Acceptance of Grounding Devices in Electrical Equipment Installation Engineering", cable trays, brackets, and derricks must be grounded.

　　從以上規(guī)范條文看，似乎電纜橋架的支架也要做接地，其實(shí)不然，我們先了解一下電纜橋架為什么要做接地。我們所說的電纜橋架接地，更明確一點(diǎn)是指電纜橋架與保護(hù)導(dǎo)體相連接，其目的是在橋架內(nèi)部的電纜發(fā)生絕緣破損而使相線與橋架接觸時(shí)（發(fā)生單相接地故障），接地故障電流能通過保護(hù)導(dǎo)體（PE線）返回變壓器的中性點(diǎn)，使得發(fā)生絕緣破損的電纜回路的保護(hù)電器能及時(shí)切除該接地故障，從而隱患，所以電纜橋架需要做接地。

　　From the above specifications, it seems that the brackets of cable trays also need to be grounded. However, this is not the case. Let's first understand why cable trays need to be grounded. The cable tray grounding we refer to more specifically refers to the connection between the cable tray and the protective conductor. Its purpose is to enable the grounding fault current to return to the neutral point of the transformer through the protective conductor (PE line) when the insulation damage occurs in the cable tray and the phase line comes into contact with the tray (single-phase grounding fault), so that the protective electrical appliances of the cable circuit with insulation damage can timely cut off the grounding fault and eliminate safety hazards. Therefore, the cable tray needs to be grounded.

　　電纜橋架作為電纜敷設(shè)的直接載體，是與電纜直接接觸的，所以會(huì)發(fā)生以上接地故障的可能，然而電纜橋架的支架并未與電纜直接接觸，也就不存在電纜絕緣破損而導(dǎo)致相線與電纜橋架支架直接接觸而產(chǎn)生的接地故障，因此電纜橋架支架的接地與否并未對(duì)電纜因絕緣破損產(chǎn)生的故障有什么影響。從T/CECS31-2017 《鋼制電纜橋架工程技術(shù)規(guī)范》對(duì)橋架的定義如下：

　　As a direct carrier for cable laying, cable tray is in direct contact with the cable, so there is a possibility of grounding faults mentioned above. However, the support of the cable tray is not in direct contact with the cable, so there is no grounding fault caused by direct contact between the phase line and the cable tray support due to cable insulation damage. Therefore, the grounding of the cable tray support does not have any impact on the faults caused by cable insulation damage. The definition of cable tray in T/CECS31-2017 "Technical Specification for Steel Cable Tray Engineering" is as follows:

　　電纜橋架：由主體（托盤或梯架）、附件和支、吊架等部件構(gòu)成，用于支承電纜線路且有一定剛度的結(jié)構(gòu)系統(tǒng)。

　　Cable tray: A structural system consisting of a main body (tray or ladder), accessories, and supports, hangers, etc., used to support cable lines and has a certain degree of rigidity.

　　由以上定義可知，電纜橋架已經(jīng)包括其安裝支架等附件，所以GB50169-2016《電氣裝置安裝工程接地裝置施工及驗(yàn)收規(guī)范》3.0.4條所寫的支架并不是指電纜橋架的支架，而應(yīng)該是指與電纜直接有接觸的（與電纜井架一樣）用于直接敷設(shè)電纜的電纜支架。

　　From the above definition, it can be seen that cable trays already include their installation brackets and other accessories. Therefore, the brackets mentioned in Article 3.0.4 of GB50169-2016 "Code for Construction and Acceptance of Grounding Devices in Electrical Equipment Installation Engineering" do not refer to the brackets of cable trays, but should refer to cable brackets that come into direct contact with cables (similar to cable racks) and are used for directly laying cables.

　　由此可知，在電纜橋架的支架沒有與電纜直接接觸的情況下，電纜橋架的支架是可以不用做保護(hù)接地的。

　　It can be inferred that in the absence of direct contact between the bracket of the cable tray and the cable, the bracket of the cable tray does not need to be protected by grounding.

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