Use of Rubber Cord in Industrial Establishment

[Jljohnson]

I have a customer with the following scenario.....
-Large workspace area with dropped suspened tile ceiling
- 120/240 volt 20 amp twist lock receptacles installed on a 20'x20' grid pattern in ceiling
- Mutiple workstations/benches set up in workspce with outlets installed on benches in a conduit system. Rubber cord power drops from grid on ceiling to junction boxes on workbenches.

This was initially set up in this manner to allow for easy relocation of workbenches on very short notice. This is a very busy company and will change an areas configuration and end-use over the course of 2-3 days quite often. They had an independent safety audit done by a 3rd party who told them that the cord is a safety hazzard and an OSHA violation but did not cite any code to back themselves up. I am being asked to give a proffessional opinion on whether they are correct or not. I can't think of any reason that this installation would be un-safe but thought I'd ask for some additional opinions before I go on record.

 

[roger]

See the links post #21 of THIS thread

Roger

 

[roger]

Here are the links I was pointing out.

http://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=INTERPRETATIONS&p_id=20709http://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=INTERPRETATIONS&p_id =20579

and

http://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=INTERPRETATIONS&p_id=20579http://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=INTERPRETATIONS&p_id =20709

Roger

 

[Jljohnson]

Roger, thanks for the links. They were helpful but not EXACTLY what I was looking for. This establishment has the power grid as I described PERMANENTLY installed in the drop ceiling. The temporary portion of the installation is the cordsets that plug into the power grid and drop to the workstations. The workstations could, in theory, remain where they are indefinitley or could need to move next week, depending on the current needs of the client. The sample that I looked at while onsite had been in the same position for well over a year. Does anybody have any info on the use of rubber cord and twist lock cord caps in this manner. I know I have seen this application or very similar applications plenty in my career but never really investigated the OSHA side of this type of installation, just made sure they were NEC compliant. FWIW, the 4-square boxes on the workstations are secured properly and all rubber cord has strain relief in place.

 

[roger]

Jim, the cords are still in violation of NEC 400.8, the aforementioned OSHA rules, and the following OSHA rules

Response: In accordance with 1910.305(g)(1)(iii), flexible cords may not be used in permanent installations as specified in (A) through (E) below:

(A) As a substitute for the fixed wiring of a structure;
(B) Where run through holes in walls, ceilings, or floors;
(C) Where run through doorways, windows, or similar openings;
(D) Where attached to building surfaces; or
(E) Where concealed behind building walls, ceilings, or floors.
​

When these cords (including extension cords) are used in temporary wiring installations, 1910.305(a)(2)(iii)(G), allows them to run through doorways or other pinch points, such as windows or other similar openings, provided they are protected from damage. This provision does not, however, except them from the other four prohibitions, (A), (B), (D), and (E) above.

Roger

 

[dezwitinc]

Cord Drops

Cord Drops

For what it is worth, we have a manufacturing facility in Miami that we have installed several hundred drops for benches in.
They each have a plugmold strip mounted under the work surface for soldering irons, test equipment, etc.
The installation consists of a box and bar hanger cut in the ceiling with a 20 amp twistlock, a cable drop and a male flanged connector on each bench.
All cord is suspended from the ceiling with a kellums grip and one on the bench end.
We have never had an inspector or the plant safety officer challenge us or even mention any problem.
I don't know if they let it pass under 400.7(A)6 or what.
Maybe they took matters in their own hands and figured that the installation met the citeria of being safe.
Note: The setup was designed and signed off on by a PE.

 

[realolman]

Jim, the cords are still in violation of NEC 400.8, the aforementioned OSHA rules, and the following OSHA rules

(A) As a substitute for the fixed wiring of a structure;
(B) Where run through holes in walls, ceilings, or floors;
(C) Where run through doorways, windows, or similar openings;
(D) Where attached to building surfaces; or
(E) Where concealed behind building walls, ceilings, or floors.




Roger

I don't see where what he describes constitutes any of the above. I don't think it's building wiring. I think the building wiring stops at the twistlocks.

The fact that they are using strain relief and twist locks seems to me to indicate an above average attempt to address safety. I don't see the hazards associated with this setup.

Why wouldn't this be permitted under 400.7 A 6 Connection of utilization equipment to facilitate frequent interchange?

 

[roger]

Realolman, here are pertinent excerpts.

Response: In accordance with 1910.305(g)(1)(iii), flexible cords may not be used in permanent installations as specified in (A) through (E) below:

and

It should be noted that OSHA interprets cord sets as being temporary wiring extensions of the branch circuit.

which takes us back to

When these cords (including extension cords) are used in temporary wiring installations, 1910.305(a)(2)(iii)(G), allows them to run through doorways or other pinch points, such as windows or other similar openings, provided they are protected from damage. This provision does not, however, except them from the other four prohibitions, (A), (B), (D), and (E) above.

And (A), (B), (D), and (E) are as follows

(A) As a substitute for the fixed wiring of a structure;
(B) Where run through holes in walls, ceilings, or floors;
(C) Where run through doorways, windows, or similar openings;
(D) Where attached to building surfaces; or
(E) Where concealed behind building walls, ceilings, or floors

Now, what ever you and I may think carries little weight in OSHA's interpretation of what is permanent, temporary, or what a temporary cord is.

For the record, I have been in many facilities that use this wiring method.

Roger

 

[jim dungar]

Now, what ever you and I may think carries little weight in OSHA's interpretation of what is permanent, temporary, or what a temporary cord is.

Roger, what is OSHA's interpretation of permanent?

If the cords are are attached to the premises wiring by means of connectors, and the table/work stations are movable, what makes this application permanent?

 

[roger]

Roger, what is OSHA's interpretation of permanent?

Beats me, I was hoping someone else would come forward with some substantiation.

Roger

 

[Jljohnson]

"1910.305(g)

Flexible cords and cables -

1910.305(g)(1)

Use of flexible cords and cables.

1910.305(g)(1)(i)

Flexible cords and cables shall be approved and suitable for conditions of use and location. Flexible cords and cables shall be used only for:

1910.305(g)(1)(i)(A)

Pendants;

1910.305(g)(1)(i)(B)

Wiring of fixtures;

1910.305(g)(1)(i)(C)

Connection of portable lamps or appliances;

1910.305(g)(1)(i)(D)

Elevator cables;

1910.305(g)(1)(i)(E)

Wiring of cranes and hoists;

1910.305(g)(1)(i)(F)

Connection of stationary equipment to facilitate their frequent interchange;

1910.305(g)(1)(i)(G)

Prevention of the transmission of noise or vibration;

1910.305(g)(1)(i)(H)

Appliances where the fastening means and mechanical connections are designed to permit removal for maintenance and repair; or

..1910.305(g)(1)(i)(i)

1910.305(g)(1)(i)(i)

Data processing cables approved as a part of the data processing system.

1910.305(g)(1)(ii)

If used as permitted in paragraphs (g)(1)(i)(c), (g)(1)(i)(f), or (g)(1)(i)(h) of this section, the flexible cord shall be equipped with an attachment plug and shall be energized from an approved receptacle outlet."

I found this on OSHA's website this afternoon. This (1910.305(g)(1)(i)(F) portion was of particular interest and relief (I hope) to both myself and my customer.

 

[realolman]

I would consider permanent as being sjo cord stapled and run through holes in studs like romex.

'Course as Roger pointed out... I ain't OSHA

 

[aja21]

Sorry to bring up an old issue but I worked in a shock absorber manufacturing plant several years ago that went through the process (successfully) to become an OSHA VPP Star site. This means that they are on the highest level of voluntary safety protection that exists in OSHAs eyes. Now, I don't have any OSHA numbers to quote and I certainly "aint OSHA" but here's what I experience during that process.
We went through quite a lengthy battle with OSHA over these same type of pendant drops as the previous electrical administration used handy boxes. What OSHA finally told us was the conduit to a box securely mounted in the ceiling, strain relief connector, no more than 6' to the Kellams grip, then a yellow safety rubber Woodhead pendant box with the receps. . Expensive but very good install.
There are over a hundred of these in that plant and OSHA is very happy with it.

 

[iwire]

then a yellow safety rubber Woodhead pendant box with the receps. .

I think that is the key item, a box 'listed' for pendant use.

Not a handy box, a 4" square box, or even a bell box with threaded hubs.

A box that is listed to be supported by the cord.

For what it's worth you can get cord with a steel wire rope inside it for pendent use as well.

 

[dlhoule]

A box that is listed to be supported by the cord.

But Bob, why do you want a box listed to be supported by the cord when the box is mounted to a bench?

 

[iwire]

But Bob, why do you want a box listed to be supported by the cord when the box is mounted to a bench?

I don't know....guess I should read the OP better.

But had it been hung a pendent box would be needed. :grin:

 

[aja21]

But Bob, why do you want a box listed to be supported by the cord when the box is mounted to a bench?

I realize also that I'm not Bob but the bench is a piece of portable frequently moved equipment plugged into the listed box via a cord. No twistlocks because that wont allow the cord to unplug if the portable bench is moved accidentally.

 

[dlhoule]

If you are strong enough to unplug that cord with kellum support in place, I am sure not going to argue with you.:grin:

 

[aja21]

If you are strong enough to unplug that cord with kellum support in place, I am sure not going to argue with you.:grin:

I wish I were, then i could go WWE and make more money for the same pain.

 

[jim dungar]

No twistlocks because that wont allow the cord to unplug if the portable bench is moved accidentally.

This is a design issue.
The type of plug is not addressed by the NEC nor OSHA.

Many customers prefer twistlocks as they do not rely only on contact pressure to "stay in place".