Disconnect Switch Working Clearance

[minesh21]

Hi,

My first post!

My question is regarding working clearances for disconnect switches. I am aware of the NEC Table 110.26(A)(1) which requires a depth of 42 inches in front of the disconnect switch. But what is the requirement of a flat, even surface for the person to stand? We have an issue where there is a small 2'' house keeping pad that extends into the working space of the disconnect switch then stops short of the 42'' requirement. I am thinking this is a tripping hazard so the pad would either have to be extended the full 42'' or removed from entering the working space entirely. Any thoughts?

 

[mwm1752]

welcome - Just a little FYI for post - details are welcome. you may have determine your circumstances require the 42" but I have little real info on the equipment - fused/unfused/likely to be energized/ I could guess 3 phase 277/480v MDP. Have no clue how far the pad encroaches or where it sets with regard to clear space. Most of the time your AHJ will help with the answer.

 

[ron]

We have not considered the encroachment of a concrete pad in our working space measurment.

Generally, distances shall be measured from the exposed live parts or from the enclosure or opening if the live parts are enclosed.

 

[charlie b]

We have had discussions on similar issues on this forum. Examples include where the panel is outdoors and the ground in front slopes downwards and where the panel is on a sloped roof. I vaguely recall someone posting a photo of a panel that had all the working space in front you could wish, except that while you were standing within that working space you were standing in a pond. I think there was even a discussion of your exact same type of issue, where the surface you would stand on does not extend the full depth of the required working clearance. My opinion is that the situation you described is unsafe. That is different than saying I could point to the words within 110.26 that would forbid it. I think the code is unclear on this subject.

Welcome to the forum.

 

[Carultch]

Hi,

My first post!

My question is regarding working clearances for disconnect switches. I am aware of the NEC Table 110.26(A)(1) which requires a depth of 42 inches in front of the disconnect switch. But what is the requirement of a flat, even surface for the person to stand? We have an issue where there is a small 2'' house keeping pad that extends into the working space of the disconnect switch then stops short of the 42'' requirement. I am thinking this is a tripping hazard so the pad would either have to be extended the full 42'' or removed from entering the working space entirely. Any thoughts?

This doesn't sound unsafe to me, even though it is difficult to make it meet the exact wording of the NEC. You wouldn't notice this as a safety hazard, unless you knew exactly what you were looking for. I do recommend making sure that you have the full 42 inches of open floor behind the extent of the housekeeping pad, so that it is 44 inches from the wall behind the disconnect to the disconnect cover.

The way that I see it, is that because raceways are allowed to penetrate the working space by up to 6 inches, a housekeeping pad or other structural member should have the same penetration limit of the work space.

Another similar example would be a 6" deep panel between two 10 inch deep exposed studs that are 24" O.C. These studs encroach on the 30" width requirement, penetrating it by 4". Yet, you could place the panel between two 12"x12" vertical wire troughs that are 24" apart, and it would meet the letter of the NEC. I see the same safety issue, whether a panelboard's working space is penetrated by studs, or by wire troughs.

 

[minesh21]

welcome - Just a little FYI for post - details are welcome. you may have determine your circumstances require the 42" but I have little real info on the equipment - fused/unfused/likely to be energized/ I could guess 3 phase 277/480v MDP. Have no clue how far the pad encroaches or where it sets with regard to clear space. Most of the time your AHJ will help with the answer.

To add clarity, this is a 480V fusible disconnect. The house keeping pad encroaches 4-5" into the working space of the disconnect.

 

[iwire]

In my opinion the wording in the NEC prohibits this but it is also very common practice.

 

[Carultch]

In my opinion the wording in the NEC prohibits this but it is also very common practice.

So is it OK for structural features (exposed studs, slabs, pads, etc) to penetrate the workspace by up to 6"?
Or is it exclusively OK for raceways and electrical equipment to penetrate the workspace by up to 6"?

I don't see the extra hazard created when a stud extends in to the workspace, any more than the hazard created by a wireway extending in to the workspace by the same amount.

I do understand rafters, joists, and other ceiling members not being permitted to penetrate the requisite 6'-6" work space height, and probably conduit shouldn't cheat the 6'-6" work space height either. But penetrating it from the same surface as the equipment itself? Hardly any issue at all, in a practical sense.

 

[iwire]

From memory I believe the section requires clear space starting at the floor.

 

[ActionDave]

From memory I believe the section requires clear space starting at the floor.

Correct.

(a) Dedicated Electrical Space. The space equal to the
width and depth of the equipment and extending from the
floor to a height of 1.8 m (6 ft) above the equipment or to
the structural ceiling, whichever is lower, shall be dedicated
to the electrical installation. No piping, ducts, leak protec-
tion apparatus, or other equipment foreign to the electrical
installation shall be located in this zone.

 

[Carultch]

Correct.

(a) Dedicated Electrical Space. The space equal to the
width and depth of the equipment and extending from the
floor to a height of 1.8 m (6 ft) above the equipment or to
the structural ceiling, whichever is lower, shall be dedicated
to the electrical installation. No piping, ducts, leak protec-
tion apparatus, or other equipment foreign to the electrical
installation shall be located in this zone.

Dedicated space refers to keeping the horizontal footprint of the equipment clear of all foreign systems, such as plumbing and HVAC. A housekeeping pad is not a foreign system. Nor is any structural object that might be in the dedicates space.

 

[mwm1752]

To add clarity, this is a 480V fusible disconnect. The house keeping pad encroaches 4-5" into the working space of the disconnect.

Sounds like a single disconnect not a breaker panel (though it technically makes no difference) in a storage closet? Is this new construction? When servicing the equipment would your feet be in contact with the 2" step? Could you trip on the step during a rapid escape from an electrical mishap? Is it possible to cut the 4-5" concrete encroachment? Is there adequate exits out of the room? Technically it is a violation but are you asking for forgiveness or dealing with existing conditions? A reliable AHJ should be consistant with decisions and also willing to evaluate circumstances. Take a picture & post --

 

[iwire]

Dedicated space refers to keeping the horizontal footprint of the equipment clear of all foreign systems, such as plumbing and HVAC. A housekeeping pad is not a foreign system. Nor is any structural object that might be in the dedicates space.

I strongly and adamantly disagree.

For instance you cannot have a structural building support column in that space.

 

[Carultch]

I strongly and adamantly disagree.

For instance you cannot have a structural building support column in that space.

That one is an obvious conflict, because a column and the equipment would occupy the same physical space.

By contrast, if you have an overhead beam cross over equipment mounted in the middle of the floor, is that a problem with the dedicated space?
It would be above 6'-6" from floor, but not 6 ft above the top of the equipment.

 

[iwire]

That one is an obvious conflict, because a column and the equipment would occupy the same physical space.

But you kind of said that would not be a problem.

Nor is any structural object that might be in the dedicates space.

By contrast, if you have an overhead beam cross over equipment mounted in the middle of the floor, is that a problem with the dedicated space?
It would be above 6'-6" from floor, but not 6 ft above the top of the equipment

That would be a violation, the only thing that can get into that space is the structural ceiling.

Workers need to be able to get into that space to add conduits etc.

 

[kwired]

Hi,

My first post!

My question is regarding working clearances for disconnect switches. I am aware of the NEC Table 110.26(A)(1) which requires a depth of 42 inches in front of the disconnect switch. But what is the requirement of a flat, even surface for the person to stand? We have an issue where there is a small 2'' house keeping pad that extends into the working space of the disconnect switch then stops short of the 42'' requirement. I am thinking this is a tripping hazard so the pad would either have to be extended the full 42'' or removed from entering the working space entirely. Any thoughts?

Establishing whether or not 110.26 applies can be tricky sometimes as there are differences in interpretations. But assuming you already determined you need the 42" - this can be subject to AHJ interpretation as well. Outdoors often the surface in front of such equipment is not perfectly flat. Stairs/steps may cause AHJ rejection, but a single 2" rise may not be seen the same as a more defined stairway and may be overlooked by some AHJ.

Ultimately the final decision that matters most here is that of your inspector.

 

[mwm1752]

That one is an obvious conflict, because a column and the equipment would occupy the same physical space.

By contrast, if you have an overhead beam cross over equipment mounted in the middle of the floor, is that a problem with the dedicated space?
It would be above 6'-6" from floor, but not 6 ft above the top of the equipment.

dedicated space extends to structural elements & only the footprint of the equipment - technically the a structural ceiling element( a wall 6'6" tall with a double top plate, the panel inside the wall. double plate is lower than 6'6") could be less than 6'6" as long as it does not extend past the front of the equipment -- we are talking clearances in front of the equipment -- now if the whole room ceiling was less than 6'6" that another story

 

[kwired]

dedicated space is above and below the equipment, working space is in front of it. They are not the same and do not overlap.

Certain items allowed in the dedicated space are allowed to enter the working space for limited distance - typical item is a gutter/wireway as long as it does not extend more then 6 inches into the working space.

 

[BOB TINI]

I'm trying to find out if a 200a fused disconnect can be placed between 6" studs at 16"oc. All working clearances in front of DS are compliant.
This is an interior application to cut power to meter and panelboard.

 

[infinity]

This thread is nearly 5 years old and this question has already been asked in this thread so please respond here:

DISCONNECT SWITCH SIDE CLEARANCE

CAN YOU INSTALL AN INTERIOR 200A FUSED DISCONNECT SWITCH BETWEEN 2x6 STUDS 16"O.C. ? IF SO , IS THERE A MIN. CLEARANCE BETWEEN THE DS AND THE STUDS? THIS IS FOR POINT OF RESIDENTIAL SERVICE ENTRY AND HELPS ELIMINATE SE CABLE OR CONDUIT BEING RUN ON THE FRONT WALL OF THE RESIDENCE SO THAT THE SE...

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