mounting boxes correctly???

[Arkansas74]

Hi all I have alway been told to secure all junction boxes weather it be on wall or to the bottom or to of a trapeze or strut. We have some contractor come in to hook up some new machines and the ran the conduit about 8 inches to a foot on the other side of the trapeze and mounted a 4sq box to it so the box is only mounted to the conduit. Then ran seal tight down to the machine. Is this legal to only mount the box to the end of emt by the ko? Where does it state in the nec about this I haven't found anything or OSHA take on this.

 

[don_resqcapt19]

314.23(E)

 

[ActionDave]

Where does it state in the nec about this I haven't found anything or OSHA take on this.

I think OSHA is mum on the subject. NEC reference is 314.23.

 

[iwire]

Does the box have threaded hubs?

Check this out ...

314.23(E) Raceway Supported Enclosure, Without Devices,
Luminaires, or Lampholders. An enclosure that does not
contain a device(s) other than splicing devices or support a
luminaire(s), lampholder, or other equipment and is supported
by entering raceways shall not exceed 1650 cm3
(100 in.3) in size. It shall have threaded entries or have
hubs identified for the purpose. It shall be supported by two
or more conduits threaded wrenchtight into the enclosure or
hubs. Each conduit shall be secured within 900 mm (3 ft) of
the enclosure, or within 450 mm (18 in.) of the enclosure if
all conduit entries are on the same side.

Exception: The following wiring methods shall be permitted
to support a conduit body of any size, including a conduit
body constructed with only one conduit entry, if the
trade size of the conduit body is not larger than the largest
trade size of the conduit or tubing:

(1) Intermediate metal conduit, Type IMC

(2) Rigid metal conduit, Type RMC

(3) Rigid polyvinyl chloride conduit, Type PVC

(4) Reinforced thermosetting resin conduit, Type RTRC

(5) Electrical metallic tubing, Type EMT

 

[ActionDave]

Bang, bang, bang. Who is batting clean up?

 

[Little Bill]

Bang, bang, bang. Who is batting clean up?

I don't know, but whoever it is can explain these couple of questions concerning this:

Exception: The following wiring methods shall be permitted
to support a conduit body of any size, including a conduit
body constructed with only one conduit entry, if the
trade size of the conduit body is not larger than the largest
trade size of the conduit or tubing:

1). what is an example of a conduit body with only one conduit entry?

2). why didn't the last part of the exception just say "if the trade size of the conduit body is not larger than the trade size of the conduit" instead of saying the largest trade size of the conduit? Why did they add "largest"?

 

[Smart $]

I don't know, but whoever it is can explain these couple of questions concerning this:

Exception: The following wiring methods shall be permitted
to support a conduit body of any size, including a conduit
body constructed with only one conduit entry, if the
trade size of the conduit body is not larger than the largest
trade size of the conduit or tubing:

1). what is an example of a conduit body with only one conduit entry?

2). why didn't the last part of the exception just say "if the trade size of the conduit body is not larger than the trade size of the conduit" instead of saying the largest trade size of the conduit? Why did they add "largest"?

1) A conduit body for a dead end circuit (e.g. possibly to support a later extension of the circuit), such as a 'C'
with one end plugged.
2) IDK

 

[Little Bill]

1) A conduit body for a dead end circuit (e.g. possibly to support a later extension of the circuit), such as a 'C'
with one end plugged.
2) IDK

I just couldn't think of a conduit body with only one conduit entry. I guess if you plug the other openings, any of them could be.

 

[iwire]

2). why didn't the last part of the exception just say "if the trade size of the conduit body is not larger than the trade size of the conduit" instead of saying the largest trade size of the conduit? [/I]Why did they add "largest"?

You might have more than one size conduit entering a conduit body.

 

[don_resqcapt19]

I don't know, but whoever it is can explain these couple of questions concerning this:

Exception: The following wiring methods shall be permitted
to support a conduit body of any size, including a conduit
body constructed with only one conduit entry, if the
trade size of the conduit body is not larger than the largest
trade size of the conduit or tubing:

1). what is an example of a conduit body with only one conduit entry?

A "E" conduit body.
http://www.tnb.com/ps/fulltilt/index.cgi?part=E27

2). why didn't the last part of the exception just say "if the trade size of the conduit body is not larger than the trade size of the conduit" instead of saying the largest trade size of the conduit?

Why did they add "largest"?

If you are using an over sized LB with reducing bushings and the LB has a volume of over 100 cubic inches, you would have to provide independent support for the LB.

If one of the two conduits (largest) is the same trade size as the LB, the independent support would not be required.

I think that when you get to LBs in 2 1/2 or 3" size you are often over 100 in?.

 

[infinity]

One entry conduit bodies (type E) are typically used to house air temperature sensors for larger buildings. From Don's link:

 

[Little Bill]

A "E" conduit body.
http://www.tnb.com/ps/fulltilt/index.cgi?part=E27


If you are using an over sized LB with reducing bushings and the LB has a volume of over 100 cubic inches, you would have to provide independent support for the LB.

If one of the two conduits (largest) is the same trade size as the LB, the independent support would not be required.

I think that when you get to LBs in 2 1/2 or 3" size you are often over 100 in?.

The exception says "conduit body of any size" I don't see where the 100 in.? applies.

Also, I didn't even consider a conduit body larger than the conduit using reducer bushings. Now it makes sense.

 

[Little Bill]

One entry conduit bodies (type E) are typically used to house air temperature sensors for larger buildings. From Don's link:

I may have seen one of those and just thought it was an LB.

 

[pjholguin]

How would the correct ambient temperature be measured with no access to ambient air? I have seen other conduit bodies used in this manner; it had another hub entry to provide access to the ambient air via a fitting.

One entry conduit bodies (type E) are typically used to house air temperature sensors for larger buildings. From Don's link:

 

[infinity]

How would the correct ambient temperature be measured with no access to ambient air? I have seen other conduit bodies used in this manner; it had another hub entry to provide access to the ambient air via a fitting.

Usually the conduit is run on the exterior of the building to a height of about 10'. The sensor is within the conduit body. The conduit, conduit body and sensor are all at the same approximate air temperature. In NYC there are many of these somewhere on old Brownstones and other commercial buildings. There is one visible in the lower right portion of this photo:

 

[Arkansas74]

It's 1 inch emt with a 4-11 metal box. The pipes are full so they can't use it for further expansion

 

[iwire]

The NEC prohibits what you describe. That box must be supported indepently of the raceways

 

[Arkansas74]

Thank y'all for the help

 

[don_resqcapt19]

The exception says "conduit body of any size" I don't see where the 100 in.? applies.

Also, I didn't even consider a conduit body larger than the conduit using reducer bushings. Now it makes sense.

Yes, the 100 in? only applies where the conduit body is of a larger trade size than the largest conduit connected to the conduit body.

Exception: The following wiring methods shall be permitted to support a conduit body of any size, including a conduit body constructed with only one conduit entry, provided that the trade size of the conduit body is not larger than the largest trade size of the conduit or tubing:...