engineers findings ?

[bure961]

We had a arc flash survey completed , it is a industrial plant 480/277 and our main switchgear has never been pm'ed in atleast 8 years . Labels have been installed to all mcc's and panels . Some mcc have been maintained. I have two questions on this , with the main switchgear not being maintained does this change the actual IE on the mcc / labels that have been install by the engineer of the study? And should a new eew policy have been put in place by the engineer? Thanks for any help .

 

[mayanees]

To answer your questions:
1) with the main switchgear not being maintained does this change the actual IE on the mcc / labels that have been install by the engineer of the study?...
The information on the label is only applicable if the gear is current in its maintenance, consistent with NETA Maintenance testing standards which can usually be met with biannual testing.
2) should a new eew policy have been put in place by the engineer?
No, it's not his place to implement policies at your facility, it's yours. You need to be in compliance with NFPA 70E. Everything you need to do is in that document.

I always say that 70E compliance starts with the arc flash analysis. The report of electrical protective device settings (Device Report) should be a part of the Study you received from the engineer. Take that Device Report and get bids from electrical testing companies to perform the required maintenance on your electrical system, to include setting the devices per the Device Report. When their work is complete, your labels are now applicable.
The next step is to have everyone at the facility receive training.
I would expect that the engineer who did the Study would be happy to guide you through the steps required to get into compliance.
John M

 

[jim dungar]

I always say that 70E compliance starts with the arc flash analysis...

I think the first step should be the ESWP. Without the saftey program how are you going to answer questions like:
What equipment will be analyzed?
What information should be on the label?
What tasks will be performed by which employees so that they know what training is needed?
Will money will be spent on mitigation, if not why waste time making recommendations?

Too many times I find the intent is to get some type of label on the equipment so that money can be wasted buying inadequate PPE. Therefore the arc flash report gets filed and an a ESWP is never created.

Does it work like this in the real world - no.
I wish more people would realize that safe electrical work is a process not a project. Less than 10% of NFPA70E deals with arc flash.

 

[mayanees]

I agree, that a more organized approach is to develop the framework for an Electrical Safety Program using the 70E Informative Annex E as a starting point.
But what I see is that companies decide to get into compliance, and then contract for a Power Study.
When we perform the analysis, we use our judgment as to what equipment gets labeled, and provide information on the labels to meet 70E requirements. We provide general training for unquailifed personnel, and more intense training directed at qualifying the appropriate people. In the training class we provide the framework to establish compliance with 70E, recommending that the facility designate a person as the Power System Owner (PSO) who is responsible for all aspects of compliance, to include: documentation; PPE mgmt; EEWP mgmt; LOTO; Preventive Maintenance; etc. If it's a large enough system, we will provide an SKM viewer package for use by the PSO in preparation of EEWPs, documentation, etc.
Mitigation is only considered for areas that are designated by the client as being interacted with.
So what I see, real world, is that 70E compliance starts with the Arc FLash Analysis.

 

[mayanees]

dup

 

[bure961]

First I like to say thanks for the very informative information given in the replies . My thinking was if there was a fault and the feeders never open in the time they are designed to open it changed the IE on the mcc breaker . Once in the passed a gf on 20amp lighting circuit caused a 600 amp feeder to trip open and shut down the mcc. The 20a cb never opened, the main breaker in the mcc never opened, and the fault went all the way to the feeding cb in the switchgear to clear the fault. And as of now after the study nothing has changed with the settings on the cb's. The engineer has made some recommandations but at this time nothing has changed. Our company has spent a lot of money on this study and now has stopped when we are close to completion. Yes we need training, a eewp atleast to get complient . Thanks again for the information and help here.

 

[jim dungar]

First I like to say thanks for the very informative information given in the replies . My thinking was if there was a fault and the feeders never open in the time they are designed to open it changed the IE on the mcc breaker . Once in the passed a gf on 20amp lighting circuit caused a 600 amp feeder to trip open and shut down the mcc. The 20a cb never opened, the main breaker in the mcc never opened, and the fault went all the way to the feeding cb in the switchgear to clear the fault. And as of now after the study nothing has changed with the settings on the cb's. The engineer has made some recommandations but at this time nothing has changed. Our company has spent a lot of money on this study and now has stopped when we are close to completion. Yes we need training, a eewp atleast to get complient . Thanks again for the information and help here.

The incident energy calculation is based on the amount of arcing fault current and the device's trip curves.
Yes, if a device fails to perform based on its curve incident energy levels may be affected.
But, if the settings of the upstream breaker overlap that of the downstream one, the incident energy value is not likely to be affected.

Ground fault values tripping coordination is often ignored unless a complete Time Current Coordination study has been ordered. Which it probably wasn't at the original equipment commissioning (they often get removed as a part of Value Engineering).

In your case it sounds more like a situation of mis-coordination, and it appears you have been given recommendations to correct this problem.

 

[ATSman]

First I like to say thanks for the very informative information given in the replies . My thinking was if there was a fault and the feeders never open in the time they are designed to open it changed the IE on the mcc breaker . Once in the passed a gf on 20amp lighting circuit caused a 600 amp feeder to trip open and shut down the mcc. The 20a cb never opened, the main breaker in the mcc never opened, and the fault went all the way to the feeding cb in the switchgear to clear the fault. And as of now after the study nothing has changed with the settings on the cb's. The engineer has made some recommandations but at this time nothing has changed. Our company has spent a lot of money on this study and now has stopped when we are close to completion. Yes we need training, a eewp atleast to get complient . Thanks again for the information and help here.

This sounds like the classic example of breaker GF trip vs phase fault tripping. I would be willing to bet that the reason the 600A breaker tripped was because it was ground fault protected. The level of fault current (probably due to a shorted 277V light ballast) that flowed was low enough to exceed the GF pickup setting of the 600A breaker (typically 10% or 60A) but not high enough for the 20A breaker to trip on instantaneous trip, which can be in the hundreds of amps for a 20ms duration.
It is not unusual for a customer to call and say my 4000A main breaker tripped on GF. We think the GFR is bad and want you to test it. Well we find out later that an electrician was changing out a 277V light ballast and caused a short to ground. Or it was just an old ballast or motor winding that went to ground. The fault travels to the most sensitive part of the system - the main GFR. The code requires that only the main breaker has to be GF protected and not the downstream feeders which leaves the typical facility with it's pants down and a headache for the chief engineer. Solution?
Add GF protection on 2nd level of feeder breakers.
If you search this forum you can probably find more written on this subject.

I have attached a letter a co-worker sent to a client regarding arc flash and arc flash studies that you might find interesting, although I have not researched the OSHA part.

View attachment Arc Flash_1.doc