MCC Cleaning

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wiredhot83

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So. Georgia
I have recently been given a new annual PM to clean and to retourqe the bussing on our mcc's at our three locations. One has a GE 8000 Line 480 V, another has an older Westinghouse 120/208V (Not sure of the model), the third had an older Westinghouse G O BHI 21500 IT 1 with a Cutler Hammer Freedom 2100 add-on all 120/208V. This is a new area for me. I have just gone over to the maintenance side from 8 years of construction, industrial and heavy commercial. And there is really no-one here at my location that has any formal electrical training, other than myself. Is this something that is normally done in-house or is it something that is typically contracted out? If done in house how detailed do you get in cleaning the bussing and how do you access it? Any help would be greatly appreciated. :?:blink::?
 
wiredhot83 said:
I have recently been given a new annual PM to clean and to retourqe the bussing on our mcc's at our three locations. One has a GE 8000 Line 480 V, another has an older Westinghouse 120/208V (Not sure of the model), the third had an older Westinghouse G O BHI 21500 IT 1 with a Cutler Hammer Freedom 2100 add-on all 120/208V. This is a new area for me. I have just gone over to the maintenance side from 8 years of construction, industrial and heavy commercial. And there is really no-one here at my location that has any formal electrical training, other than myself. Is this something that is normally done in-house or is it something that is typically contracted out? If done in house how detailed do you get in cleaning the bussing and how do you access it? Any help would be greatly appreciated. :?:blink::?
Click to expand...

Ok, firstly I do have some experience on this but it may not be specifically how you all are gearing up to do this.

1) You would need to coordinate with the local POCO to have the power turned off for the specific time that it would take to perform the PM. There is not valid reason to attempt this while the systems are energized. If someone tells you thats not true...have them do it !
2) Typically you would simply set your torque device to the verified settings of the equipment and if none are present then view NEC Annex I and/or UL 486A-B for guidance and reading prior to doing any PM on this equipment. be careful as re-torquing does not mean over-tightening terminations...the T device should click close to the existing settings if done correctly originally even if pre AA8000 AL is encountered.
3) If the process requires local inspection (if did in the jurisdiction I worked in) then you need to coordinate that with the inspection department as it will likely be an after hours inspection and will cost extra.
4) Most of the time we used a compressed air system to blow out dust and so on and just recheck terminals, existing insulation and bracing of conductors if present, look for overheated terminations, damaged insulation at termination and so on.

Again yours may be different...but thats all that took place for PM's when we inspected them. And we really did nothing more than look at it and ask "are you done" and when the company doing the PM said yes we issued a ticket to permit the power company to reconnect and wait for the next PM.

Of course that was the standard practice for Switchboards and so on on, if the MCC can be isolated with proper PPE and put in a safe condition with LO/TO then refer to NFPA 70E for more details on a good procedure.
 
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I agree with MasterTheNEC.

We use to have a contract for electrical equipment cleaning in a manufacturing plant. The facility had (7) 25KV inside substations along with numerous MCC''s. We would do two a year during scheduled plant outages.

If there are no normal yearly shut downs they will simply have to schedule some.


Roger
 
Thanks yeah loto WILL definitely be a part of the procedure. our procedure is very vague as to the actual steps we are to take. the entire procedure says "Inspect the electrical switch gear, clean all equipment, tighten all mechanical connections and repaired as required. " that's all I've been given to go off of.:slaphead:
 
Two small things to add-
if you use compressed air to blow the dust out, that dust has to go somewhere. If the MCC is indoors, plan on some sort of dust collector. (Even a household furnace filter over a box fan is better than nothing.)

There have been several conversations about re-torquing bolts in the forums here. The capsule version seems to be using a clicker torque wrench and if it immediately clicks, go no further. Do no use a beam torque wrench and do not loosen/tighten. (Remember, loose bolts are more of a problem than over-tight ones.)
 
I would suggest a vacuum cleaner in lieu of compressed air. There are some interesting OSHA rules about the use of compressed air for such purposes that are routinely ignored. And as another poster mentioned, the dust needs to go somewhere. Better it get sucked up into the vacuum cleaner than just moved around.
 
Think safety

Think safety

After shutting down the system we also grounded the main with ground straps made for that purpose. This was an added step for safety and the shutdown and startup procedure was in writing with instruction on testing and removal of straps. As for maintenance we checked all connections in the buckets, checked starter contacts, checked stabs on back of bucket, and checked torque on splices connectors. And yes learn how the torque wrench works before tightening bolt, I had a guy break 3 before he came to me and asked why it's not ratcheting at proper torque, he did not know it just clicked.
 
petersonra said:
I would suggest a vacuum cleaner in lieu of compressed air. There are some interesting OSHA rules about the use of compressed air for such purposes that are routinely ignored. And as another poster mentioned, the dust needs to go somewhere. Better it get sucked up into the vacuum cleaner than just moved around.
Click to expand...
A combination of vacuum first and the air has some advantages.
There are places that you cannot easily reach with the suction and brush, but air works at a distance.
 
just the cowboy said:
After shutting down the system we also grounded the main with ground straps made for that purpose. This was an added step for safety and the shutdown and startup procedure was in writing with instruction on testing and removal of straps. As for maintenance we checked all connections in the buckets, checked starter contacts, checked stabs on back of bucket, and checked torque on splices connectors. And yes learn how the torque wrench works before tightening bolt, I had a guy break 3 before he came to me and asked why it's not ratcheting at proper torque, he did not know it just clicked.
Click to expand...


Protective grounding is generally not advisable in low voltage equipment because the conductors and attachments have to be engineered to safely carry the available fault current until the upstream ocpd opens. This is covered in NFPA 70E 120.3 Temporary Protective Grounding Equipment.

(B) Capacity. Temporary protective grounding equipment
shall be capable of conducting the maximum fault current
that could flow at the point of grounding for the time necessary
to clear the fault.
(D) Impedance. Temporary protective grounding equipment
and connections shall have an impedance low enough
to cause immediate operation of protective devices in case
of accidental energizing of the electric conductors or circuit
parts.

Link to OHSonline article: http://ohsonline.com/articles/2013/06/01/applying-personal-protective-grounds.aspx
 
petersonra said:
I would suggest a vacuum cleaner in lieu of compressed air. There are some interesting OSHA rules about the use of compressed air for such purposes that are routinely ignored...
Click to expand...
Are you just thinking of the PSI safety limits or are there actually some rules that apply to this type of electrical maintenance?
 
Is an air jet really necessary? If you can get the dust with a vacuum and maybe a brush, great, but is it necessary to get every last speck? I don't think it is. Might need an extra-long wand for the vac for this, and maybe a dust-brush on a stick, but that ought to be enough. (This isn't a remanufacturing process, just in-situ cleaning.)
 
zbang said:
There have been several conversations about re-torquing bolts in the forums here. The capsule version seems to be using a clicker torque wrench and if it immediately clicks, go no further. Do no use a beam torque wrench and do not loosen/tighten. (Remember, loose bolts are more of a problem than over-tight ones.)
Click to expand...

Is re-torquing a good idea? Seems some of those conversations brought up reasons why not to. Perhaps thermal imaging is a better idea and leave the existing connections alone unless there is a problem area detected from thermal imaging.
 
kwired said:
Perhaps thermal imaging is a better idea and leave the existing connections alone unless there is a problem area detected from thermal imaging.
Click to expand...

TI is a great thing, but brings up the "live work" problem, and I wouldn't consider as part of cleaning. I'd be inclined to check for loose bolts with both fingers and a clicker. The emphasis is that if a bolt seems tight, it probably is. I've also used the wiggle-the-wire method on lugs & breakers. If the wire moves in the lug, it isn't tight :D.
 
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