engineer/electrician?

[wireday]

I work with a engineer,we build production machines.They are one of a kind to make a certain product. The machine requires an electric clutch with a pulley to drive a wheel. The engineer purchased a clutch with wire leads maybe #16,the clutch is 90 volts DC, 1amp. the clutch has no type of strain relief for conductors. At the time being it has been installed with a 1/4 plastic air line over the conductors but there is nothing to keep it in place. I consider this a hazard,If the conductors were to get pulled or damaged. I believe this clutch was designed to be installed inside a machine not out in the open. I have been ask to show In the code where this is a violation. I know in addition to the NFPA70 there is also a machine handbook which I am not so familiar with.Can anyone tell me where to look?

 

[gadfly56]

I work with a engineer,we build production machines.They are one of a kind to make a certain product. The machine requires an electric clutch with a pulley to drive a wheel. The engineer purchased a clutch with wire leads maybe #16,the clutch is 90 volts DC, 1amp. the clutch has no type of strain relief for conductors. At the time being it has been installed with a 1/4 plastic air line over the conductors but there is nothing to keep it in place. I consider this a hazard,If the conductors were to get pulled or damaged. I believe this clutch was designed to be installed inside a machine not out in the open. I have been ask to show In the code where this is a violation. I know in addition to the NFPA70 there is also a machine handbook which I am not so familiar with.Can anyone tell me where to look?

Check the manufacturer's installation manual to see if the clutch is intended/permitted to be installed as they have it. See if the clutch is UL listed for a particular use.

 

[gar]

140304-1737 EST

Sounds very similar to a Maxi-Torq clutch good for about 1000 to 1500 #-ft of torque at possibly 2000 RPM.

See http://www.cjmco.com/products/electric-brakes/ema_electric-brake-specs.shtml EMA950. The photo or sketch shows a compression clamp on the wire.

I would create a bracket to support a Sealtite flexible conduit for wire protection.

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[wireday]

Good ideas, Seal tight/liquidtight would only be able to come close to the clutch,As there is no hub or connection point.I will check the manufacturer tomorrow.

 

[gar]

140304-2335 EST

The following link provides a better idea of the MaxiTorq fitting on the coil part of the package. This is used to prevent rotation of the coil and as a means of attaching flexible conduit.

http://www.cjmco.com/products/electric-clutches/multiple-disc-clutches-ema.shtml

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[pjholguin]

I have worked on production machines going 23 years, and this a normal wiring method within the machine enclosure. It may seem odd but there are different rules to the wiring methods within the production equipment , if the production equipment has pasted a certification from a Listing agency then it has meet the rules/code that it is required to meet. There are several qualifying entities for different industries, you should be able to find the build specifications for your type of production equipment from them.

PJHolguin

I work with a engineer,we build production machines.They are one of a kind to make a certain product. The machine requires an electric clutch with a pulley to drive a wheel. The engineer purchased a clutch with wire leads maybe #16,the clutch is 90 volts DC, 1amp. the clutch has no type of strain relief for conductors. At the time being it has been installed with a 1/4 plastic air line over the conductors but there is nothing to keep it in place. I consider this a hazard,If the conductors were to get pulled or damaged. I believe this clutch was designed to be installed inside a machine not out in the open. I have been ask to show In the code where this is a violation. I know in addition to the NFPA70 there is also a machine handbook which I am not so familiar with.Can anyone tell me where to look?

 

[wireday]

This is designed to be inside an enclosure.It has been installed outside of an enclosure,and its possible an operator could be around it.The clutch is a new tourque SC-425-11. I was more looking for code reference from NFPA 70 and 79 to show where this is not protedcted correcty. I have found 6.1 and 14.1.2.4 in NFPA79

 

[just the cowboy]

keep looking

keep looking

Keep looking it is in there somewhere it says wires in side of a machine can be run in the open, all others must be protected. It should not be done that way and they should agree on that and just manup and order the right one for safety reasons.

 

[wireday]

Thanks Cowboy

 

[Timbert]

I consider this a hazard,If the conductors were to get pulled or damaged. [...] I have been ask to show In the code where this is a violation.

I always find this irksome. Why do some people assume, if the code doesn't prohibit it, it must be safe. :rant: We've heard it a lot, the code is merely the minimum requirements.

NFPA 79 definitely looks like it would be applicable here.

Chapter 13 Wiring practices is your friend here.

I'd point to 13.4.2.2, which states conductors external to the electrical enclosure shall be in raceways, except where following 13.1.6, which states among other things that the cables be supported in a manner that they will not be damaged.

I don't think 1/4-inch air line qualifies as a 'raceway.' :roll:

Another approach would be re-evaluate the system hazard analysis (you do have one, don't you? :happyno What is the hazard from the cable being damaged. It at least exposes the operator to 90VDC. What happens to the machine and or product if the clutch doesn't work?

 

[gar]

140305-1107 EST

Aside from protecting the wire there seems to be some inconsistency. A clutch with 25 #-ft capability should not require 100 W of coil power. The Maxi-Torq that I mentioned has about 1200 #-ft capability at about 100 W.

On the drawing for the SC-425-11 torque is listed as 25 #-ft, note the correct units are used here at the top. At the bottom of the sheet a note states 24 V DC (95). What does that mean, and no current is specified, or resistance. Next static torque is listed as 240 in-#. Wrong units, should be #-in, and 240/12 = 20 #-ft, not 25 #-ft.

Since the coil is prevented from rotation by a tab you can make a bracket to support Sealtite right up to where the cord enters the clutch. I see no reason the Sealtite has to actually attach to the coil housing.

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[just the cowboy]

Run sealtight to it then build a guard around it so it is internal to the machine, if they don't want to replace it

 

[wireday]

Thanks, This is what I was looking for

 

[kwired]

This is designed to be inside an enclosure.It has been installed outside of an enclosure,and its possible an operator could be around it.The clutch is a new tourque SC-425-11. I was more looking for code reference from NFPA 70 and 79 to show where this is not protedcted correcty. I have found 6.1 and 14.1.2.4 in NFPA79

I don't know all those safety design specs and standards, but my own common sense tells me when it comes to protecting a person from voltage exposure near the assembly, you have to remember it is generally in a mechanical hazard area as well and that it likely has mechanical guards that will limit people from getting close enough to be exposed to any electrical hazard.

 

[Aleman]

I have worked on production machines going 23 years, and this a normal wiring method within the machine enclosure. It may seem odd but there are different rules to the wiring methods within the production equipment , if the production equipment has pasted a certification from a Listing agency then it has meet the rules/code that it is required to meet. There are several qualifying entities for different industries, you should be able to find the build specifications for your type of production equipment from them.

PJHolguin

I concur, especially with clutches and/or brakes. Many times these are just loose wires ran through a grommet in the cover.