Working clearance on the side of equipment

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bnbowen@uiuc.edu

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A 32 inch wide, 100 Hp, 480 volt VFD is to be mount on a rack. A 12 inch wide input filter is to be mounted adjacent the VFD as close as possible on the left side (within reason-several inches). There is nothing on the right side of the VFD. Can I put all of the working clearance for the VFD on the right side and for the input filter on the left side?
 
If I'm understanding your installation then yes. The 30" working space width is for in front of the equipment and is not required to be centered on the equipment itself.
 
bnbowen@uiuc.edu said:
A 32 inch wide, 100 Hp, 480 volt VFD is to be mount on a rack. A 12 inch wide input filter is to be mounted adjacent the VFD as close as possible on the left side (within reason-several inches). There is nothing on the right side of the VFD. Can I put all of the working clearance for the VFD on the right side and for the input filter on the left side?
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If you do not need to work on the back or sides of the equipment, you don't need working space on the back or sides of the equipment.

The 30" width of the working space can be measured from anywhere along the front of the equipment. From the left, from the right, or anywhere in between.
 
Also remember 110.26(A) says "Working space for equipment operating at 600 volts, nominal, or less to ground and likely to require examination, adjustment, servicing, or maintenance while energized shall...."

IMO if this doesn't require examination, adjustment, etc. while energized then there is no working clearance required. That is sometimes a tough judgement call to make and often AHJ requires working space regardless.
But when working space is required the equipment in question does not need to be centered in the required space. It can be all the way to the left, all the way to the right or anywhere in between.
 
kwired said:
Also remember 110.26(A) says "Working space for equipment operating at 600 volts, nominal, or less to ground and likely to require examination, adjustment, servicing, or maintenance while energized shall...."

IMO if this doesn't require examination, adjustment, etc. while energized then there is no working clearance required. That is sometimes a tough judgement call to make and often AHJ requires working space regardless.
But when working space is required the equipment in question does not need to be centered in the required space. It can be all the way to the left, all the way to the right or anywhere in between.
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Is that how you trouble shoot VFD's K - Completely shut down?
 
Carultch said:
If you do not need to work on the back or sides of the equipment, you don't need working space on the back or sides of the equipment.

The 30" width of the working space can be measured from anywhere along the front of the equipment. From the left, from the right, or anywhere in between.
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Thanks so much for the help. If I understand this correctly, the 12" wide filter will require 18" of space on either side that can be broken up however it will fit even though there is nothing on the sides to work on. I'm assuming this is for conduit space and space for someone to work on the filter from the front.

My fear with the 32" wide VFD is the AHJ will have a problem with raceway entering and leaving the sides. Is there a minimum requirement for this.

It appears that I could mount the filter right next to the VFD and put 18" on the other side of the filter. Does this seam reasonable? It'll work for me but I don't know about the AHJ. - He worries me. :eek:))

Thanks again!
Brad
 
bnbowen@uiuc.edu said:
Thanks so much for the help. If I understand this correctly, the 12" wide filter will require 18" of space on either side that can be broken up however it will fit even though there is nothing on the sides to work on. I'm assuming this is for conduit space and space for someone to work on the filter from the front.

My fear with the 32" wide VFD is the AHJ will have a problem with raceway entering and leaving the sides. Is there a minimum requirement for this.

It appears that I could mount the filter right next to the VFD and put 18" on the other side of the filter. Does this seam reasonable? It'll work for me but I don't know about the AHJ. - He worries me. :eek:))

Thanks again!
Brad
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Usually the spaces on the back or sides of the equipment, are determined by the manufacturer's requirements (if any). Often this is to allow a space for air to flow and draw the heat away from it.

Another reason you might need space on the back or sides of equipment, is if there are non-electrical components to maintain. Filters, vents, components such as that. Components that you cannot access from the front. It wouldn't be as large of a working space as you need for electrical components, but it is wise to plan accordingly. I believe it is 30" deep, but I can't find a reference for that. And that is if you ONLY can access the non-electrical components from the back or sides. If you can access the filters from the front, you don't need 30 inches on the sides.

It is common practice to put the conduits thru the sides of the equipment. Seldom any issue.
 
bnbowen@uiuc.edu said:
Thanks so much for the help. If I understand this correctly, the 12" wide filter will require 18" of space on either side that can be broken up however it will fit even though there is nothing on the sides to work on. I'm assuming this is for conduit space and space for someone to work on the filter from the front.

My fear with the 32" wide VFD is the AHJ will have a problem with raceway entering and leaving the sides. Is there a minimum requirement for this.

It appears that I could mount the filter right next to the VFD and put 18" on the other side of the filter. Does this seam reasonable? It'll work for me but I don't know about the AHJ. - He worries me. :eek:))

Thanks again!
Brad
Click to expand...


You've got it. The 12 inch wide device will require 18 inches on either the left side, or the right side. OR some combination that adds up to 18 inches on both sides. Because 12 + 18 = 30, and that is the requisite width. In any case, all hinged doors or lids must be able to open a complete quarter turn.

And working space width can overlap with adjacent equipment. Three 20" panels only need the width of the three panels plus maybe some gap for conduits between them (if applicable). You don't need 90 inches total working width, only the width of the equipment sum.
 
mwm1752 said:
Is that how you trouble shoot VFD's K - Completely shut down?
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That is how 70E would like us to troubleshoot everything:p

I have examined/measured voltage/current/etc. at junction boxes that were far from having 110.26 working space why stop with panelboards, motor controllers, etc?

Otherwise isn't input voltage measurent or setting of parameters via a communications device just about all that gets done in the field while the drive is energized? Do you replace capacitors or rectifier with the drive energized? I'd say when there is a bad capacitor or rectifier it is often confirmed that it needs major repair without even opening the unit up, especially for small drives that often cost as much or more to repair then to just replace the entire drive.
 
kwired said:
That is how 70E would like us to troubleshoot everything:p

I have examined/measured voltage/current/etc. at junction boxes that were far from having 110.26 working space why stop with panelboards, motor controllers, etc?

Otherwise isn't input voltage measurent or setting of parameters via a communications device just about all that gets done in the field while the drive is energized? Do you replace capacitors or rectifier with the drive energized? I'd say when there is a bad capacitor or rectifier it is often confirmed that it needs major repair without even opening the unit up, especially for small drives that often cost as much or more to repair then to just replace the entire drive.
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Your "sometimes a tough call" had me confused. I try to use the "Horse Sense" method but do tend to lean on the side of life safety first. Back when we were staring fires with sticks I was standing on an aluminum ladder, working on a live j box, in a metal joist type ceiling. Working clearances are not required and I was sure glad my boss was able to catch me as I was jolted off the ladder from a rookie mistake. Saw white that day learned more than I wasnted to.:blink:
 
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