Project Class I Division 1

[Student_UL]

Hello all,
I am student and I designing a machine for Class I Division 1 location and have some question regarding the installation and the typical start up procedure of the machine.

Between the motor and the control panel the connections are performed by a RMC with sealing.
After installation the conduit system, it will be checked by a worker in the factory.

• Does this worker need a special authorization or training?
• Are functional tests after sealing necessary?
• Is there a requirement that any inspector of an authority have to inspect the conduit system before start up of a machine?

The motor should be controllable by a pendant control which have to be flexible.
Therefore I have to use a flexible cord. The circuit is performed in intrinsically safety technology.
I have read the complete NFPA 70, but I am uncertain in this topic and how I have to perform.
Also I have no practical experience.

• Which type of cord is allowed to use therefore and which components are necessary for connecting this cord (more than 10 conductors) with the control panel?
• Nearly the same problem I have with a temperature sensor. The sensor is permanent connected with the cable. What I do have to consider for connecting this sensor with the control panel?

Could you please help me in this matter?

Thank you very much!

Student_UL

 

[augie47]

As far as your wiring methods for the intrinsically safe circuits most any wiring method is acceptable. Sealing should be addressed at the control panel. (see NEC 504.20)

As to requirements at assembly: many US jurisdictions would require that the assembled equipment bear the label of a Nationally Recognized Lab (NRTL) which would somewhat assure the end user that all standards have been met in terms of design and assembly. The particulars required for the NRTL label would be set forth by the testing lab itself.
NEC in 90.7 only requires inspectors to check for alterations and damage on NRTL listed
equipment.

I have no knowledge of assembly requirements to meet European standards such as C-E

 

[petersonra]

As to requirements at assembly: many US jurisdictions would require that the assembled equipment bear the label of a Nationally Recognized Lab (NRTL) which would somewhat assure the end user that all standards have been met in terms of design and assembly. The particulars required for the NRTL label would be set forth by the testing lab itself.
NEC in 90.7 only requires inspectors to check for alterations and damage on NRTL listed
equipment.

What NRTL listing would cover such an assembly? You could cover the control panel via UL698a but nothing outside of the control panel itself is covered by that listing.

 

[petersonra]

I am student and I designing a machine for Class I Division 1 location and have some question regarding the installation and the typical start up procedure of the machine.

This kind of question is always a bit scary because the poster essentially starts out by saying they are unqualified to be doing the work they are describing.

Between the motor and the control panel the connections are performed by a RMC with sealing. After installation the conduit system, it will be checked by a worker in the factory.

So far so good.

Does this worker need a special authorization or training?

Unlike in Europe, no special training or 3rd party involvement is required to deal with equipment that will go into classified areas. There are still all kinds of requirements that would suggest it is necessary that the workers involved be trained appropriately, but it is not like there is a direct government mandate on this.

Are functional tests after sealing necessary?

Pretty much the same answer. However, you do have an obligation under the UCC to produce a product that is useful and meets the requirements that have been contractually agreed to.

Is there a requirement that any inspector of an authority have to inspect the conduit system before start up of a machine?

The short answer is "no". The long answer is that whether or not it is inspected by someone representing a governmental entity is highly variable depending on many factors including local rules and practices where the piece of equipment is installed.

I would point out that in many (but not all) localities the control panel itself would require listing to UL698a.

The motor should be controllable by a pendant control which have to be flexible.
Therefore I have to use a flexible cord. The circuit is performed in intrinsically safety technology.

This does not seem like anything grossly unusual, but IS may not be required. It is one way to do what you want to do safely.

I have read the complete NFPA 70, but I am uncertain in this topic and how I have to perform.

NFPA70 is not an instruction manual. I think it actually says so somewhere in the book.

Also I have no practical experience.

It might well be wise to find someone who has some experience to help you.

Which type of cord is allowed to use therefore and which components are necessary for connecting this cord (more than 10 conductors) with the control panel?

Since you have described the circuits as being IS, just about any kind of cord listed in the NEC could be suitable. Note that cord is not the same thing as cable.

Nearly the same problem I have with a temperature sensor. The sensor is permanent connected with the cable. What I do have to consider for connecting this sensor with the control panel?

If the cord is long enough to reach into the enclosure, you could just route it there directly. However, such cords are often relatively small and subject to damage so it might be wise to find some way of protecting the cable.

Could you please help me in this matter?

Given the potential for disaster with such a design were it done incorrectly and managed to make it into service anyway, is it wise for us to do so?

I would point out that given it is a CID1 design, an explosion proof motor would likely be required.

It might be wise to consider not pouring the seals at the factory. If something has to be fixed in the field it is very hard to dig the wires and cable out of the sealing compound.

 

[augie47]

What NRTL listing would cover such an assembly? You could cover the control panel via UL698a but nothing outside of the control panel itself is covered by that listing.

I have inspected assembled equipment which bore the label of a NRTL.
As far as this particular animal, it looks like it might possibly fall under NNGZ or NNNY with UL.
On a recent inspection in a lumber mill locally SGS, a NRTL, certified the control cabinet and all factory installed associated wiring (to control stations, limit switches, etc.)

As one of our members asserts: " If you can write a big enough check....."

 

[petersonra]

I don't know what nngz is but nnny only covers the control panel and not the whole assembly.

A separate label could cover the control station.

 

[rlundsrud]

I don't know the code reference, if there is one. This is just from my experience, but I can't recall every running RMC directly to a motor. I always transitioned to an ECLK (often called a horse c##k) and that would connect into the motor. I am guessing it is to handle vibration caused by the motor, again I don't know if it is required by code, but I think it is a good practice.

Bob

 

[Smart $]

I don't know the code reference, if there is one. This is just from my experience, but I can't recall every running RMC directly to a motor. I always transitioned to an ECLK (often called a horse c##k) and that would connect into the motor. I am guessing it is to handle vibration caused by the motor, again I don't know if it is required by code, but I think it is a good practice.

Bob

Flexible connection to motor is not required by Code. That said, it is practiced without fail in good designs.