Underground cable,Road crossing,& Regulations 2

[T83]

Hello,

I would like to know what are the regulations or requirements on the following issue,it can be related to any code none specific.In the case of a buried underground cable I have read once(can't remember where) & saw on many drawings that at a road crossing cables are installed in PVC ducts/conduit,what I want to know is this always required ?I mean if the cable is armored & has mechanical protection (such as cable covers,etc.),is the conduit/duct still required ? can somebody guide me towards something official plz!

Thx!!

 

[dpc]

The voltage, which you haven't told us, might make some difference.

But basically this is going to be up to the entity that owns the road you are going under. Normally this will be a state highway department or city engineering department. Just be thankful that it isn't a railroad.

Generally, common sense dictates putting the cable in some form of conduit, to allow replacement when the cable fails without the need to rip up the pavement or bring in a directional boring rig. Usually extra empty conduits are installed as well.

 

[7anoter4]

I agree with dpc .But you can traverse the road [not a rail road!] even Direct Buried cable if you keep a minimum depth.
The National Electric Safety Code section 32 Table 352-1 indicates the minimum depth for Direct Buried, Single Duct or Duct Bank. See:

http://books.google.com/books?id=A0...X&oi=book_result&resnum=1&ct=result#PPA366,M1

Also NEC Table 300-5 for low-voltage cable [Since I didn't yet purchase the last edition of NEC I am not sure it is the right number of this table]
is permitted for Direct Burial, Rigid Metal and Nonmetallic Conduit and other. The minimum depth under roads shall be 24 inches.
For High-Voltage [more than 600 V rated] Table 710-4(b) the same way of cable protection , for different rated voltage from 24-42 inches for Direct Burial but not less of 24 inches for protected cable, in area subject to vehicular traffic.

 

[dpc]

Yes, the NEC does give minimum cover requirements. But if this is utility cable, the NEC doesn't apply. And any more stringent highway department requirements will trump the NEC.

 

[T83]

Hello,

dpc thank you for your input,I see where you are going with the cable being a utility & 7anoter4 I checked table 300-5 from the NEC 2008,according to the table I can install a cable at a depth of 600mm (24 inch).

Guys I bought the NEC 2008 & the BS7671,do you recommend any material or guides to help me understand them & highlight stuff?I am lacking a lot regarding code interpretation

Thank you!

 

[ScottyUK]

BS7671 has about seven guidance notes would normally be worth buying, but they are due for an update to reflect the recent issue of the 17th edition of BS7671. I would wait for the new releases rather than buy them now.


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

 

[jghrist]

You can get a handbook for NEC at

http://www.nfpa.org/catalog/product.asp?pid=70HB08&order_src=A208