Transcript Chapter 10 – Electric Box Installation

Chapter 10 – Electric Box Installation
CHAPTER 6
BOXES
Chapter 10 – Electric Box Installation
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
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Chapter 10 – Electric Box Installation
Selecting the Appropriate
Electric Box Type
• Consider whether it
will be used in new or
old work.
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Chapter 10 – Electric Box Installation
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
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Chapter 10 – Electric Box Installation
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.
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Chapter 10 – Electric Box Installation
Installing Nonmetallic Device
Boxes
• Most common method
– nail them directly to a
wood framing member.
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Chapter 10 – Electric Box Installation
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.
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Chapter 10 – Electric Box Installation
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.
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Chapter 10 – Electric Box Installation
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.
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Chapter 10 – Electric Box Installation
BOX PARTS
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knock outs
fittings
connector
conduit bodies
ground clip
bushing
box extension
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Chapter 10 – Electric Box Installation
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
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Chapter 10 – Electric Box Installation
CONDUCTOR SIZE
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No. 14...............................
No. 12...............................
No. 10...............................
No. 8...............................
No. 6...............................
2. cubic inches
2.25 cubic inches
2.5 cubic inches
3. cubic inches
5. cubic inches
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