MCC Buckets & 70E

[Electrobe]

We are in the process of becoming 70E compliant. Currently an ARC-Flash analysis has been done and all our MCC's have been labeled with the IE @ 18Inches and the required PPE. This label is based on the MCC bus fault current and the MCC main-feeder breaker clearing times.

Should this same PPE level be worn when working in a MCC bucket (disconnect on or off) since the load side of the breaker is still energized?

Thanks

 

[Electrobe]

We are in the process of becoming 70E compliant. Currently an ARC-Flash analysis has been done and all our MCC's have been labeled with the IE @ 18Inches and the required PPE. This label is based on the MCC bus fault current and the MCC main-feeder breaker clearing times.

Should this same PPE level be worn when working in a MCC bucket (disconnect on or off) since the load side of the breaker is still energized?

Thanks

Oops I meant LINE SIDE.

 

[mdshunk]

Oops I meant LINE SIDE.

That's still exposed energized parts.

 

[jim dungar]

Should this same PPE level be worn when working in a MCC bucket (disconnect on or off) since the load side of the breaker is still energized?

Yes.

Not only is the line side still energized (and usually exposed), most MCC buckets do not provide complete isolation. A fault in any part of the MCC will try to exit through the bucket you have open.

 

[mdshunk]

I think there's even been people involved in arc flash explosions just from jostling the bucket around. Something messed up with the bus.

 

[VinceS]

Was the HRC level based on the 04 o 09 70E?

If you don't mind me asking could you specify if you were allowed any HRC 0 levels unless the MCC buckets were de-energized at the source?

 

[iwire]

I think there's even been people involved in arc flash explosions just from jostling the bucket around. Something messed up with the bus.

No one was injured but I have seen a bucket door that was bowed out like a bowling ball hit it at high speed from inside the MCC. I was very surprised the screws had held it shut.

 

[Electrobe]

Was the HRC level based on the 04 o 09 70E?

If you don't mind me asking could you specify if you were allowed any HRC 0 levels unless the MCC buckets were de-energized at the source?

All our HRC's were based on the 2004 NEC code but since we are just getting rolling I am planning on changing to the 2009 code. This will mean that all the labels will need to be changed since they listed the PPE on the label and the PPE has changed in the 2009 code. All our MCC's are HRC 1 or 2 with one that is a HRC 3.

 

[zog]

All our HRC's were based on the 2004 NEC code but since we are just getting rolling I am planning on changing to the 2009 code. This will mean that all the labels will need to be changed since they listed the PPE on the label and the PPE has changed in the 2009 code. All our MCC's are HRC 1 or 2 with one that is a HRC 3.

If you did an arc flash analysis the changes in the 2009 70E have no effect, except the facesheild is now needed for HRC 1.