Running TECK Cable In Conduit

[djansson]

I have a question regarding running TECK cable within conduit...

Table 19 of the CEC lists which types of cables are allowed to be installed using different methods (cable tray, direct buried, enclosed raceways, etc).

For the "enclosed raceway" row of the table, TECK cable is not listed as being an allowable cable for this type of installation. I know typically we would just direct bury TECK cables, but I have seen in the field where duct banks were installed with conduits, and TECK cables were pulled in at a later date. Which seems to be in conflict with the code.

I've also seen numerous posts in Eng-Tips where people are discussing running TECK in conduit, without any corrections from the guru's.

Any insight guys?

Best Regards.

Dan.

 

[7anoter4]

In my opinion –I have not the CEC last edition so I cannot be sure-table 19 does not refer to any underground duct bank-as NEC is referring.
You may run the cable through a duct or conduit but you have to derate the ampacity since there will be a temperature drop in the conduit.
You have to know the losses in the armor-eddy current or circulating current if the armor is grounded in more than one point.

 

[waross]

I think that the answer is yes, in Canada you may instal TECK cable in conduit.
See:
Table 19
Conditions of use and maximum allowable conductor temperature of wires and
cables other than flexible cords, portable power cables, and equipment wires
(See Rules 4-008, 4-040, 12-100, 12-302, 12-602, 12-606, 12-902, 12-904, 12-1606, 12-2104, 12-2202, 22-202,
and Tables 1, 2, 3, 4, D1, and D3 and Appendix I.)

Table D1 lists AC90, ACWU90, and some TECK cables as having an overall jacket.

12-602 Use (see Appendix B)
(6) Armoured cable with overall jacket shall be permitted for use in a raceway when it is installed in accordance
with Rule 12-902(2).

12-902 Types of conductors and cables (see Appendices B and I)
(1) Conductors and cables shall be of types suitable for use in raceways as indicated in Table 19.
(2) Notwithstanding Subrule (1), armoured cables as described in Rule 12-602(6) shall be permitted to be
installed in a conduit or tubing, provided that
(a) the installation will not result in a greater fill than that specified in Table 8; and
(b) the installation conforms to one of the following conditions:
(i) the length of cable pulled into the conduit or tubing does not result in the calculated maximum
pulling tension or the calculated maximum sidewall bearing pressure being exceeded; or
(ii) the run of conduit or tubing between draw-in points does not have more than the equivalent
of two 90° bends with minimum radii of not less than 0.944 m for cable rated 1000 V or less
and 1.524 m for cable rated in excess of 1000 V, and is limited to a maximum of
(A) 15 m for a three-conductor copper cable;
(B) 45 m for a single-conductor copper cable;
(C) 35 m for a three-conductor aluminum cable; or
(D) 100 m for a single-conductor aluminum cable.

Appendix B Notes on Rules
Rule 12-902
Armoured cables intended to be pulled into conduit or tubing are subject to damage when the maximum pulling
tension is exceeded or the sidewall bearing pressure is beyond the capability of the cable. Typically, the limiting
factor in these installations is the sidewall bearing pressure. Cable specification data and calculation methods to
determine the acceptable length of cable to be pulled into a raceway are available from cable manufacturers.
Furthermore, the minimum cable bending radius must be considered. There may be different values for the
minimum bending radii depending on the type of cable. The cable manufacturer should be consulted for
accurate values of the minimum bending radii of specific cables.
The examples of acceptable installations described in Item (2)(b)(ii) are based on a maximum cable size of
1000 kcmil and a run of raceway with a 90° bend at each end, using bends with a 0.944 m radius for low-voltage
cable and bends with a 1.524 m radius for high-voltage cable. Installations beyond these parameters should have
calculations completed to establish acceptability.

While tha code is primarily concerned with side wall pressure there may be another issue. The armour on some lots of TCK cables fits quite loosely. There is a possibility that the conductors may be pulled through the armor. TECK listed for hazardous locations (marked HL) has the armor wound quite tightly around the inner jacket or covering. I would check the price difference and consider spec'ing HL rated TECK for installation in conduit.


Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[djansson]

Thanks for the response guys!

Dan.

 

[trio2chiz]

Hi Dan,

we asked the same question to one of the Code committee member and his answer was clear:
"No you cannot run Teck cable in conduit, you have to stick to the Table 19 as indicated in article 12-100".

The reason is that the heat dissipation for a Teck cable in a conduit is «unknown», so the ampacity cannot be determined. As 7another4 mentionned, you must derate the ampacity of the cable, but how? This question is not answered by the CEC.

Al

 

[kmh1]

In my opinion armoured cable is allowed in conduit as per Rule 12-902 (2) as long as fill ratio and pulling tensions are not exceeded. Multiconductor power cables larger than #1/0 installed according to Diagram B4-4 need to follow the ampacity tables D14 A and B. Rule 4-004 (1)(d) and (2)(d) describe the ampacity of metal armoured cables greater than #1/0 in a raceway based on these tables.