Manholes for electrical cables enetring building?!

[eleecsunil1965]

Is there any standard which specifies the requirement of manhole before the underground power cables enters building Main switch board room?Is this is standard industrial practice?In one of the Industrial control room building project i am doing in middle-east, designer/consultant has proposed such man holes.I have seen manholes for underground telephone and fibre optic cables before it enters building.Cables specified as12Nos.4Corex 240 Sq.mm Cu/XLPE/SWA/PVC, 0.6/1kV grade.Distance from trasformer secondary to main switch board room approximately 50mtrs.

 

[PHovnanian]

I don't know what codes you have to comply with in the Middle East. ere in the USA, the NEC and NESC don't require such manholes. Their use may be advisable based the distance the cable needs to be pulled from the transformer. It'll be easier to make a long pull into the manhole and then a short one from there into the service entrance equipment.

It also depends on who owns the cable. In some cases, its the utilities practice to provide the underground service to a point outside the building and then splice onto the customer's service entrance conductors. The utility will then specify a manhole for this purpose.

 

[ScottyUK]

You might possibly need a pull-pit if the cable route is awkward, changes direction, or the cables are particularly heavy section. Difficult to much more than speculate without seeing the drawing.


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If we learn from our mistakes I'm getting a great education!

 

[7anoter4]

If the cables are crossing access road or if one expect large expansion in the future the cable duct bank will be recommended. The cable duct bank routing will be provided with manholes all 30-40 m in order to facilitate cable pulling. Close to a building the last manhole may be provided with a window and a throat up to the building so a cable tray can be used instead of conduits.
Care should be taken sealing this tray against water penetration from the manhole.

 

[alehman]

As far as I know, there is no code requirement for a manhole unless it's needed for pulling. The manhole can help prevent water from entering the building through the conduits if it has adequate drainage.



Alan
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"It’s always fun to do the impossible." - Walt Disney