LBY Between Seal-Off and Motor

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session88

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I was inspecting a Class I, Division 1 area and found some of the CI, D1 rated motors have Seal-Off's near motor enclosures and some do not. Also some that have Seal-Off's have LBY's between the Seal-Off and motor enclosure. The LBY's have removable covers.

I assume the motors that have Seal-Off's do not have a Manufacture Rated Seal between Stator and motor enclosure? I will have to verify nameplate ratings.

I also found a few CI, D1 light fixtures with Seal-Off's. Some had the same LBY installed between Seal and Light Fixture.

Is it ever ok to install a fitting/condulet with a removable cover between a Seal-Off and an enclosure, motor, light fixture or device that requires the Seal-Off? I actually see a lot of electricians make this mistake when entering/exiting CI, D1 areas with conduit and Seal-Off's.

Do CI, D1 rated motors that have a Manufacture Seal between stator and enclosure still require a Seal-Off?
 
If the LBY is an explosion proof fitting it would be permitted between the enclosure that requires the seal and the seal.
501.15(A)(1) ... Conduit seals shall be installed within 450 mm (18 in.) from the enclosure. Only explosionproof unions, couplings, reducers, elbows, capped elbows, and conduit bodies similar to L, T, and Cross types that are not larger than the trade size of the conduit shall be permitted between the sealing fitting and the explosionproof enclosure.
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session88 said:
I was inspecting a Class I, Division 1 area and found some of the CI, D1 rated motors have Seal-Off's near motor enclosures and some do not. Also some that have Seal-Off's have LBY's between the Seal-Off and motor enclosure. The LBY's have removable covers.

I assume the motors that have Seal-Off's do not have a Manufacture Rated Seal between Stator and motor enclosure? I will have to verify nameplate ratings.

I also found a few CI, D1 light fixtures with Seal-Off's. Some had the same LBY installed between Seal and Light Fixture.

Is it ever ok to install a fitting/condulet with a removable cover between a Seal-Off and an enclosure, motor, light fixture or device that requires the Seal-Off? I actually see a lot of electricians make this mistake when entering/exiting CI, D1 areas with conduit and Seal-Off's.

Do CI, D1 rated motors that have a Manufacture Seal between stator and enclosure still require a Seal-Off?
Click to expand...

Do any of the motors need a seal fitting?

Read 501.15(A)(1) carefully, and take the following quote from that section into consideration:

"The enclosure contains apparatus, such as switches, circuit breakers, fuses, relays, or resistors, that may produce arcs, sparks, or temperatures that exceed 80 percent of the autoignition temperature, in degrees Celsius, of the gas or vapor involved in normal operation."

There may be other factors in determining the need for a seal, but that is kind of the basics of when they are required. Some motors may not have arcing or sparking parts inside. Those that do are probably single phase with a starting capacitor cutout switch, or may have an internal overload switching device, or other design that may allow for too high of temperature to be reached.

Same with lighting - if it normally doesn't have arcing/sparking components - it generally doesn't require a seal within 18 inches. Seals are still needed when leaving the classified area though.
 
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