Moulding is very extensively used for electric circuit work, in extending circuits in buildings which have already been wired, and also in wiring buildings which were not provided with electric circuit work at the time of their erection. The reason for the popularity of moulding is that it furnishes a convenient and fairly good-looking runway for the wires, and protects them from mechanical injury.

It seems almost unwise to place conductors carrying electric current, in wood casing; but this method is still permitted by the National Electric Code, although it is not allowed in damp places or in places where there is liability to dampness, such as on brick walls, in cellars, etc.

The dangers from the use of moulding are that if the wood becomes soaked with water, there will be a liability to leakage of current between the conductors run in the grooves of the moulding, and to fire being thereby started, which may not be immediately discovered. Furthermore, if the conductors are overloaded, and consequently overheated, the wood is likely to become charred and finally ignited. Moreover, the moulding itself is always a temptation as affording a good "round strip" in which to drive nails, hooks, etc. However, the convenience and popularity of moulding cannot be denied; and until some better substitute is found, or until its use is forbidden by the Rules, it will continue to be used to a very great extent for running circuits outside of the walls and on the ceilings of existing buildings. Figs. 9, 10, 11, and 12 show two- and three-wire moulding respectively; and Table VII gives complete data as to sizes of the moulding required for various sizes of conductors.

While the Rules recommend the use of hardwood moulding, as a matter of fact probably 90 per cent of the moulding used is of white-wood or other similar cheap, soft wood. Georgia pine or oak ordinarily costs about twice as much as the soft wood. In designing moulding work, if appearance is of importance, the moulding circuits should be laid put so as to afford a symmetrical and complete design. For example, if an outlet is to be located in the center of the ceiling, the moulding should be continued from wall to wall, the portion beyond the outlet, of course, having no conductors inside of the moulding.

Fig. 9. Two Wire Wood Moulding

Fig. 9. Two-Wire Wood Moulding.

Fig. 10. Two Wire Wood Moulding.

Fig. 10. Two-Wire Wood Moulding.

If four outlets are to be placed on the ceiling, the rectangle of moulding should be completed on the fourth side, although, of course, no conductors need to be placed in this portion of the moulding. Doing this increases the cost but little and adds greatly to the appearance.

Fig. 11. Three Wire Wood Moulding

Fig. 11. Three-Wire Wood Moulding.

Moulding is frequently used in combination with other methods of wiring, including armored cable, flexible steel tubing, and fibrous tubing. In many instances, it is possible to fish tubing between beams or studs running in a certain direction; but when the conductors are to run in another direction or at right angles to the beams or studs, exposed work is necessary. In such cases, a junction-box or outlet-box must be placed at the point of connection between the moulding and the armored cable or steel tubing.

Where circuits are run in moulding, and pass through the floor, additional protection must be provided, as required by the Code Rules.

Fig.12. Three Wire Wood Moulding.

Fig.12. Three-Wire Wood Moulding.

to protect the moulding As a rule, it is better to use conduit for all portions of moulding within six feet of the floor, so as to avoid the possibility of injury to the circuits. Where a combination of iron conduit or flexible steel tubing is used with moulding, it is well to use double-braided conductors throughout, because, although only single-

braided conductors are required with moulding, double-braided conductors are required with unlined conduit, and if double-braided conductors were not used throughout, it would be necessary to make a joint at the outlet-box where the moulding stopped and the conduit work commenced. Where the conductors pass through floors, in moulding work, and where iron conduit is used, the inspection authorities, in order to protect the wire, usually require that a fibrous tubing be used as additional protection for the conductors inside of the iron pipe, although, if double-braided wire is used, this will not usually be required. Fig. 13 shows a fuseless cord rosette for use with moulding work. Fig. 14 shows a device for making a tap in moulding wiring.

Table VII. Sizes Of Mouldings Required For Various Sizes Of Conductors

FIG. No.

TYPE OF MOULDING

NUMBER OF WIRES

MAXIMUM SIZE OF WIRE B AND S. GAUGE

DIMENSIONS IN INCHES

SOLID

STRANDED

A

Aa

Ab

Ac

B

Ba

Bb

Bc

C

Ca

9

A-2

2

12

14

1 1/2

1/2

1/4

1/4

27 32

5/8

7 32

1/4

1/8

3

16

9

A4

2

6

10

1 11/16

1_ 2

5

16

9 32

29 32

11

16

7 32

5 16

5/16

3 16

9

A-6

2

4

5

2

1 2

7 16

5 16

1 1/16

13 16

1 4

7

16

I 9

16

7 32

9

A-8

2

1

2

2 3/8

1

2

9

16

3

8

1 3/16

15 16

1 4

9/16

| 13 16

9

32

9

A-9

2

-

3/0

3

5/8

3 4

7 16

1 13/32

1 1/8

9 32

3 4

2 7/16

9 32

10

A-10

2

-

250.000 C M.

3 15/16

II

16

7

8

3 4

1 11/16

1 3/8

5 16

7

8

_

-

10

A-11

2

-

400,000 CM.

4 7/8

15 16

1

31 32

2 3/16

1 7/8

5 16

1

11

B-2

3

12

14

23/16

7 16

1

4

9 32

27 32

5

8

7 32

1

4

1 13/16

3 16

11

B4

3

8

I0

2 1/2

15 32

5 16

5 16

29 32

ii

16

7 32

5

16

2 1/8

3 16

11

B-6

3

4

5

2 7/8

13 32

7 16

3

8

1 1/16

13

16

1 4

7 16

2 3/8

1

4

11

B-8

3

1

2

3 5/8

19 32

9 16

3

8

1 3/16

15 16

1 4

9 16

3 1/16

9 32

1 1

B-9

3

-

3//o

4 5/16

9

16

3

4

15 32

1 13/32

1 1/8

9 32

3 4

3 3/4

9 32

12

B-10

3

-

250OOO CM.

5 1/2

23 32

7/8

23 32

7/8

1 3/82

5 16

7/8

_

12

B-11

3

-

4 0Q0O0 CM.

6 3/4

15

16

1

15 16

2 3/16

1 7/8

5 16

1

-

-

Moulding work, under ordinary conditions, costs about one-half as much as circuit run in rigid conduit, and about 75 per cent, under ordinary conditions, of the cost of armored cable. Where the 1atter method of wiring or the conduit system can be employed, one of the other of these two methods should be used in preference to moulding.

Wires Run In Moulding 090017Wires Run In Moulding 090018Wires Run In Moulding 090019Wires Run In Moulding 090020

as the work is not only more substantial, but also safer. Various forms of metal moulding have been introduced, but up to the present time have not met with the success which they deserve.