Glove Testing

I just got my gloves back from testing and I have a few that failed that I plan to use for 'show and tell' in a safety meeting. Most likely, I'll be asked what voltage was used to cause the failure. Does anyone know the test voltage for Class 0 gloves under ASTM D120?

TxEngr

It should be marked on these, but anyways.

Class 0 - 5000V
Class 1 - 10kV
Class 2 - 2Kv
Class 3 - 3kV
Class 4 - 4kV

(These are test voltages, not use voltages)

I have boxes and boxes full of failed gloves, every kind of failure you can think of, one of the best training aides ever. My favorites are the Ozone Damaged ones, common failure mode for the gloves but most users wouldnt know what it looks like (It looks like dry rot)

I suggest you read OSHA 1910.137 (Focus on section b) at your safety meeting so your guys know how to do a proper inspection of thier gloves. www.osha.gov

I think Zog means

Class 2 - 20kV
Class 3 - 30kV
Class 4 - 40kV

If only spell check had an Electrical Engineering function to it

Yep, just seeing if anyone was paying attention, yeah, thats what I was doing.

Let's not forget the Class 00 glove:

Here they are:
Class 00 - Test 2,5KV - Max use - 500vac
Class 0 - Test 5KV - Max use - 1KV
Class 1 - Test 10kV - Max use - 7.5KV
Class 2 - Test 20Kv - Max use - 17KV
Class 3 - Test 30kV - Max use - 26.5KV
Class 4 - Test 40kV - Max use - 36KV

Regards,

VFD's

Does anyone have any experience in programming small VFD's while wearing Cat 2 PPE? The power has to be on to do this and it is very challenging to work the small key pad while wearing insulated gloves with leather protectors.

My solution was to move the HMI to the door so everything could be performed door closed. Allen Bradley and ABB both make the remote kits and I suspect that other manufacturers do as well. The kits are overpriced, but it sure beats trying to press small buttons wearing gloves. If your drives don't have a remote capability, threaten to change brands. That might get your vendor to think about that option.

Also, does your drive have the capability of applying a lower voltage (I'm assuming these are 480V drives) allowing you to bench set the parameters prior to installation? Your final option is to have the vendor program them prior to delivery.

Just a few ideas. I feel your pain though.

TxEngr

Then use a screwdriver, or another pointy object

Seriously, remote keypad (mounted outside the enclosure) or networked VFD (DeviceNet, Ethernet, etc.) can be programmed without opening their panel.

What about doing a NFPA 70E Annex F Hazard/Risk Evaluation. If your consultant your probably going to stay away from this method. But working inside your company may be different.

I have done this type of documentation on equipment before. The plan is - there is a need to adjust or view an electronic parameter or PLC connection or IO. The HRC is a 1 or less and the enclosure contains shielded or finger safe devices in the area of the PLC, VFD or DC Drive. This type of analysis is used to evaluate the hazard for task specific work. The form is analogous in nature and not based on actual data and you must know the IE and done your data analysis.

However, I see some real benefit to using this method for electrical enclosures that contain electronic setup or monitoring devices. The form I create is task specific and I regard several items in the enclosure that have a risk and I identify those and provide some method of mitigation technique to reduce the risk if needed. These forms are then used in qualified worker training for awareness to the task specific work and precautions to take.

The issue using gloves that I also look at is-
1) Is your hand or body parts within the restricted shock boundary? If so then you have to look at moving the MMI to a remote or perform some mitigation technique. If not within the restricted boundary you don't have to wear the gloves anyways, but good to evaluate the risk on the form.
2) Condition and design of the enclosure.
3) Exposed terminals
4) Loss of equipment control while making adjustment and mitigation technique.
Just a few examples of hazards to evaluate and consider in the documentation.

It something to think about. Your hazard my be too high for this method but I see it as an option. It's only an Annex and not a standard but NFPA 70E group must have thought it was a useful tool to include in the book. It's up to your policy or plan on using this type of document.

Hoffman has some arc resistant enclosures designed secifically for this application, pretty afordable too.

Therefore, regardless of where a VFD is mounted in a cabinet, you can't adjust parameters without wearing proper PPE since you are within the "restricted approach boundry" due to the 480v input to the VFD.

Is that a correct statement?

1910.137 allow 0 and 00 dielectric gloves to be used without leather protectors. In addition, 70E would not require leather protectors if the HRC is 0. That should make it easier. On the other hand, I use 00 gloves with lamb skin gloves and that is as good as it gets for dexterity.