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Earthing Arrangements for Enclosures

Shaun Scholes
A & B supplies going through manual transfer switch to 2No DBs. 
I'm concerned that this enclosure and CPCs are not bonded or installed correctly. I've also got concerns that the switch isn't wired correctly, according to the schematic. 
Bonding
  • The SWAs have been glanded into the removable panels but there is no fly-lead connecting to the main enclosure. As far as I'm aware there is a rubber seal between the removable panel and the main enclosure to maintain the IP rating. I appreciate there are nuts and bolts holding this in place, but would this be sufficient as a connection? 
  • The CPCs from the supply have been bonded to the side panel of the housing, and the CPCs from the DBs have been bonded to rear panel of the housing but they have not been connected together. Although everything is connected through the housing it doesn't appear to be a robust connection. 
Switch
ABB 0T100F4C
Schematic arrangement below. 
From the data sheets and diagrams available from ABB, I don't believe the switch operates how the schematic is drawn. Meaning that essentially supply A is connected to one side of outputs from the switch and supply b connected to the other side. The switch provides 3 modes of operation - All off, Side I on with Side II off, and Side II on with side I off. 
I'd like to hear thoughts and opinions on this please.
 
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    I'm not convinced about the continuity between the removable plates and the enclosure.

    The nuts look like these share.google/zHImExch34BBDORoP which abrade the surface on tightening. And no pics of the top of the enclosure showing star washers under the bolt heads. If they are there, and the nuts are as above, then tightening the bolts should abrade both surfaces. But there is a seal in between the plates, so you wouldn't achieve full torque, and full abrasion, without the risk of destroying the seal, not good for a removable panel. 

    I think the nut seen between the glands at the top connects two overlapping banjos. Perhaps the surface of the plate below the banjos has been abraded for good contact, but the nut and washer visible have neither a star washer or any special nut. So might not be a good connection to the plate, but probably a good connection between the two SWAs. I'm thinking the whole enclosure is designed for water or something ingress, so the 3 holes in the top plate might need seals. If there, they would further degrade any efforts to provide earth continuity.

  • 0 in reply to OlympusMons
    OlympusMons said:
    I think the nut seen between the glands at the top connects two overlapping banjos.

    I agree that that is possible. I wondered why the nut and bolt were there, but I thought that it would be a bit odd to put banjos on the outside, because they would be less susceptible to environmental effects inside.

  • 0 in reply to OlympusMons

    I couldn't find any particular details on this but according to the label but apparently the housing is IP65. I attempted to speak with ABB but I was referred to Google AI search results for technical details. 

  • 0 in reply to Shaun Scholes

    Neither the Data sheet for those boxes 
    which is https://docs.rs-online.com/559b/A700000013016936.pdf

    Nor The accessories list at the end of this catalogue page 

    https://docs.rs-online.com/1417/0900766b8112997f.pdf 

    make any  mention of fitting any earthing of links. So, taking account of makers instructions, perhaps they are not needed.

    But... 
    The how to build it picture in the datasheet is barely worthy of IKEA, and might be implying paint removal or it may be just a badly drawn drill bit ! 
    local judgement is required, and as I said above perhaps a measurement of resistance  beats four aces ! 




    Mike 

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