Arc Flash High Levels

[steve66]

I have an old switchboard with a fused main. The arc flash study for the main bus indicates that the cal/cm^2 is high enough to put it in the "dangerous" category (i.e. - the "no safe PPE exists).

What does this mean in terms of operating the main switch with the doors closed? Does it mean that is prohibited? I think I've seen posts that seem to indicate at least some on this forum believe that is the case.

Does anyone have a reference?

If that is the case, how is one supposed to handle the situations where older equipment is in the "dangerous" category.

 

[Jraef]

If the doors are closed and properly latched, not vented, in good working condition to factory specs and regularly maintained, you need no PPE to operate it. Proving all of that may be difficult though.

It does also mean that there is ZERO option of working on it live.

 

[wbdvt]

Operating the device would be a risk analysis and you can refer to NFPA 70E-2018 Table 130.5(C) and Informative Annex F for guidance.

Since you have a study, the incident energy can be determined at other distances. This will help in determining if there are distances where AR PPE is available. Is it possible to do the work at a distance greater than 18"? For example, your risk analysis may indicate that the switch can be operated safely with no AR PPE required. However, to do a voltage check to determine the absence of voltage would require the door to be open. Could the door screws be loosened, then the door opened with a 3 ft hotstick (assuming 3 ft puts you into an IE that has PPE), connect some voltage probes to insulated sticks and perform the voltage check remotely.

Is this old switchboard protected upstream by a breaker with adjustable instantaneous settings? If so, did the analysis look at the effect of reducing the incident energy and coordination by lowering the instantaneous setting?

 

[GoldDigger]

This is one of the situations that either portable or permanently installed remote actuators are designed for.

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[steve66]

Is this old switchboard protected upstream by a breaker with adjustable instantaneous settings? If so, did the analysis look at the effect of reducing the incident energy and coordination by lowering the instantaneous setting?

No, its actually a substation, with the xformer in an adjacent enclosure. So I think the xformer is bussed directly to the main.

This is one of the situations that either portable or permanently installed remote actuators are designed for.

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Do they make a portable actuator that would operate a 2000 amp bolted pressure switch? Or does the switch have to be turned off and the cubicle opened to install the actuator?

 

[GoldDigger]

Do they make a portable actuator that would operate a 2000 amp bolted pressure switch? Or does the switch have to be turned off and the cubicle opened to install the actuator?

AFAIK you can get them to fit almost anything with a handle as long as there is a way to mount it to the outside of the enclosure. Google and find a manufacturer to call. I am sure they will be happy to advise you.

 

[texie]

No, its actually a substation, with the xformer in an adjacent enclosure. So I think the xformer is bussed directly to the main.




Do they make a portable actuator that would operate a 2000 amp bolted pressure switch? Or does the switch have to be turned off and the cubicle opened to install the actuator?

View attachment 19780

As I recall, bolted pressure switches could be ordered with a motor to charge the closing spring so you could remote close it. This looks like maybe Square D. Even if a little old many of these parts are available. A good sales engineer could run this down. Remote opening should be easy with what is already there.
You need Zog to weigh in on this-he will know.

 

[jblackmer]

As I recall, bolted pressure switches could be ordered with a motor to charge the closing spring so you could remote close it. This looks like maybe Square D. Even if a little old many of these parts are available. A good sales engineer could run this down. Remote opening should be easy with what is already there.
You need Zog to weigh in on this-he will know.

For a temporary actuator look for "Chicken Switch" they make a nice unit that has magnetic mounts to hold the actual actuator with a long cord and switch that plugs in. Several other mnaufacuers make similar devices.

 

[zog]

There are around 200 different actuators. This is an older catalog so contact them if you don't see what you need here.

https://www.cbsarcsafe.com/wp-content/uploads/2017/05/ArcSafe_ProdCat_2015_lores.pdf

 

[jim dungar]

Do they make a portable actuator that would operate a 2000 amp bolted pressure switch? Or does the switch have to be turned off and the cubicle opened to install the actuator?

The switch in your picture is close to 40 years old, at the youngest. Has it been operated regularly? Has it been been maintained per the manufacturer's schedule? If not, there is a very high probability it will not function correctly, the mechanism is likely to jam.

Instead of trying to add parts to turn it into an electric operated device, you might want to consider replacing it with a breaker.

 

[steve66]

The actuators and chicken switches are an interesting thought.

The switch in your picture is close to 40 years old, at the youngest. Has it been operated regularly?

No.

Has it been been maintained per the manufacturer's schedule?

And No.

If not, there is a very high probability it will not function correctly, the mechanism is likely to jam.

Instead of trying to add parts to turn it into an electric operated device, you might want to consider replacing it with a breaker.

I think this was installed in the early 70's, so yes, 40-50 years old is spot on. I'm almost positive it hasn't been operated in at least the last 20 years. The probability of the switch not working correctly or not reclosing has been discussed. The long term plan is to replace the whole substation.

When you say "replace it with a breaker", is it possible to install a breaker in the same switchboard? Like swapping out the bucket? It is a square d power style switchboard.

 

[jim dungar]

I think this was installed in the early 70's, so yes, 40-50 years old is spot on. I'm almost positive it hasn't been operated in at least the last 20 years. The probability of the switch not working correctly or not reclosing has been discussed. The long term plan is to replace the whole substation.

When you say "replace it with a breaker", is it possible to install a breaker in the same switchboard? Like swapping out the bucket? It is a square d power style switchboard.

Yes it might be possible, it depends on the size of the enclosure. It is more complicated than swapping a bucket, but vendor service shops have done enough that it is relatively easy for them.

Personally, I would not operate your switch without having a repair crew at the ready.