motor power cable connections in hazardous areas

[REEngineer]

There are several motors located in a gas treating plant. They are mostly fractional horse power motors made by Baldor and US Motors and are used in gas processing. On an occaion, I noticed that there are no connection terminals inside the motors' connection boxes, so winding ends and input power cables' ends have been just taped together inside the boxes. Although connection boxes are claimed to be explosion-proof and sealed by neopern gaskets, I still think there must be a better way for such critical connections.

 

[petersonra]

Re: motor power cable connections in hazardous areas

The explosion proof housing is there to cool any gases that ignite inside the box to the point that they will not ignite a hazardous atmosphere as they exit the box.

The makeup of the connections is not an issue.

 

[don_resqcapt19]

Bob,
If there is a gasket, the enclosure is not an explosion proof enclosure.
Don

 

[don_resqcapt19]

REEngineer,

so winding ends and input power cables' ends have been just taped together inside the boxes.

I'm sure that they are not just taped together. Most likely there are ring terminals on each conductor and machine screws holding the ring terminals together. The tape just insulates the connection. This is the most common industrial connection that I know of. The only small polyphase motors that I have ever seen with terminals were IEC design motors and not NEMA.
Don

 

[petersonra]

Bob,
If there is a gasket, the enclosure is not an explosion proof enclosure.
Don

good point. i missed the gasket part.

i wonder if they really are explosion proof then.

 

[don_resqcapt19]

Bob,
Unless it is a Class I Division 1 area, explosion proof motors are not required, as long as the motor has no arc producing parts.
Don

 

[REEngineer]

Assuming we can't do anything about the taped wires, I need to know the protection class required for just preventing a spark inside the connection box (or even winding) from reaching outside and causing an explosion in case of gas leakage or something. Is TEFC class enough or should it be XPFC or something else?

 

[rbalex]

If these are fractional motors, are they single or three-phase?

In general, single-phase motors must be explosionproof in both Divsion 1 and 2 locations.

Depending on the frame constuction, for some fractional HP motors, the entire enclosure including the motor terminal box is rated as a single explosionproof unit. In those cases there must be a seal at the raceway terminus.

 

[petersonra]

Bob,
Unless it is a Class I Division 1 area, explosion proof motors are not required, as long as the motor has no arc producing parts.
Don

The OP did use the words "explosion proof".

 

[don_resqcapt19]

Bob,

The OP did use the words "explosion proof".

Yes he did, but I have never seen an explosion proof enclosure with a gasket.
Don

 

[petersonra]

Bob,

The OP did use the words "explosion proof".

Yes he did, but I have never seen an explosion proof enclosure with a gasket.
Don

me either.

usually they have an o-ring instead of a gasket.