chapter 10 – electric box installation chapter 6 boxes
TRANSCRIPT
Chapter 10 – Electric Box Installation
CHAPTER 6
BOXES
Chapter 10 – Electric Box Installation
2
Selecting the Appropriate Electric Box Type
• Considerations when selecting an electrical device– Single-gang– Two-gang– Three-gang or more
• Information found on electrical plan
Chapter 10 – Electric Box Installation
3
Selecting the Appropriate Electric Box Type
• Consider whether it will be used in new or old work.
Chapter 10 – Electric Box Installation
4
USES PERMITTED
• Minimum depth 1/2 inch in depth• Used for luminaries must be rated for that
purpose• Luminaries that weigh more then 50 pounds
must be supported independently• Ceiling fans shall be installed with boxes rated
for that purpose• Must be accessible
Chapter 10 – Electric Box Installation
5
BOX MOUNTING
• In non-combustibles materials boxes shall be mounted not more then 1/4 in from surface
• In combustible materials boxes must be mounted flush with wall surface
• Article 314.20• Gaps larger then 1/8 in around a box must be
repaired.
Chapter 10 – Electric Box Installation
6
Installing Nonmetallic Device Boxes
• Most common method– nail them directly to a
wood framing member.
Chapter 10 – Electric Box Installation
7
Installing ‘Old Work’ Boxes in Existing Walls and Ceilings
– Metal straps that spread open and do not allow the box to come back out of the hole.
Chapter 10 – Electric Box Installation
8
Installing ‘Old Work’ Boxes in Existing Walls and Ceilings
• To install ‘old work’ boxes, cut a hole into the wall or ceiling at the location where you wish to mount the box.
• The plaster ears keep the boxes from going too far into the hole, but there has to be some other device that will keep the box from coming back out of the hole.
Chapter 10 – Electric Box Installation
9
Installing ‘Old Work’ Boxes in Existing Walls and Ceilings
– Sheetrock grips that are tightened to hold the box firmly in the wall or ceiling.
– Madison Hold-Its (also known as Madison Straps or Madison Hangers), thin metal straps installed on each side of an ‘old work’ box to provide a secure attachment.
Chapter 10 – Electric Box Installation
10
BOX PARTS
• knock outs
• fittings
• connector
• conduit bodies
• ground clip
• bushing
• box extension
Chapter 10 – Electric Box Installation
11
BOX FILL• Article 314-16
• all conductors count toward fill allotment
• only fittings and clamps that are on the inside of box count toward fill allotment
• devices that have a mounting strap or A yoke count as two conductors
• all ground wires count as one conductor
• pig tails do not count
Chapter 10 – Electric Box Installation
12
CONDUCTOR SIZE• No. 14............................... 2. cubic inches
• No. 12............................... 2.25 cubic inches
• No. 10............................... 2.5 cubic inches
• No. 8............................... 3. cubic inches
• No. 6............................... 5. cubic inches