Working area around large electrical equipment.

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Ataber

Member
Location
Rocklin CA
Hello all,

I'm trying to find a solution to a problem my technicians regularly face in the field. We service, and commission large utility scale solar inverters. They are typically installed on a metal platform that is secured to the ground on concrete pilings, then buried/covered with gravel so that the platform is at grade or close to grade. The issue is, some of our customers install the equipment above the grade, anywhere from 4-16 inches above grade. Now my technicians don't have a good working space to access the components inside of our equipment. UNLESS they use a small ladder/step stool. The problem with this, is they are now leaning into the equipment, as there is usually 1-5 inches on the "deck" of the platform in front of the inverter. This makes the job incredibly unsafe, as we have 1000v DC, and 345v AC inside of this machine.

I have been searching around in section 110.26 about working area, and most of it covers the height, the width, and the depth. Which isn't an issue EVER because these installs are outside. Is there anything in the code that discusses a platform, or a sentence that calls for a LEVEL working area in front of the equipment?

Any help would be greatly appreciated.

Thank you for your time,

-Auston

IMG_5755.jpg
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
I see the concrete base as being a violation of 110.26(A). It would have to stop flush with the face of the equipment or extend out to the required work space depth to not be a violation.
 

Carultch

Senior Member
Location
Massachusetts
I see the concrete base as being a violation of 110.26(A). It would have to stop flush with the face of the equipment or extend out to the required work space depth to not be a violation.

I would think there would be some margin on that. You often have to extend the slab enough beyond the footprint and anchor bolts of the equipment, for concrete structural properties with the edge distance. A small extension of a housekeeping slab up to 6" penetrating the workspace would be acceptable, even though the NEC doesn't explicitly say that it is. It presents no more hazard than a 6" deep raceway penetrating the workspace depth.
 

iwire

Moderator
Staff member
Location
Massachusetts
I would think there would be some margin on that. You often have to extend the slab enough beyond the footprint and anchor bolts of the equipment, for concrete structural properties with the edge distance. A small extension of a housekeeping slab up to 6" penetrating the workspace would be acceptable, even though the NEC doesn't explicitly say that it is. It presents no more hazard than a 6" deep raceway penetrating the workspace depth.

There is no margin
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
That was a change I was going to submit but didn't get to it. The house keeping pad should be permitted to extend 6".
 

ADub

Senior Member
Location
Midwest
Occupation
Estimator/Project Manager
When I do pads I either go 3" or less or 3' or more. No code specific reason.


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jim dungar

Moderator
Staff member
Location
Wisconsin
Occupation
PE (Retired) - Power Systems
You are correct it is steel but the code issue is the same.

What you are looking at is the steel framed concrete filled base of a invertor(?)+transformer skid assembly. It is not a housekeeping pad, it is an integral part of the manufacturer's equipment.
 

Tony S

Senior Member
What you are looking at is the steel framed concrete filled base of a invertor(?)+transformer skid assembly. It is not a housekeeping pad, it is an integral part of the manufacturer's equipment.

I’ve worked for 24 years in the cement manufacturing industry. As of yet I haven’t seen concrete you could directly bond a ground jumper to. It’s a fabricated skid unit.

Safe access is still the problem
 

jim dungar

Moderator
Staff member
Location
Wisconsin
Occupation
PE (Retired) - Power Systems
I still see it as a 110.26 violation.

Clearances appears to be adequate, what is missing is a suitable level (?) work platform, which is not a NEC requirement.
The possible violation is between the gravel and the top of the skid frame, not the electrical enclosure. This is not much different than working space for 'ceiling mounted HVAC' equipment which can only be accessed from some type of portable work platform.
 

iwire

Moderator
Staff member
Location
Massachusetts
Clearances appears to be adequate, what is missing is a suitable level (?) work platform, which is not a NEC requirement.

Clearances yes, but the work space is not NEC adequate, it must be unobstructed to the surface I am standing on.

So either that panel has to move out flush with the skid or they need to build a platform at the same eight as the skid.
 

Tony S

Senior Member
Clearances appears to be adequate, what is missing is a suitable level (?) work platform, which is not a NEC requirement.
The possible violation is between the gravel and the top of the skid frame, not the electrical enclosure. This is not much different than working space for 'ceiling mounted HVAC' equipment which can only be accessed from some type of portable work platform.

It isn’t any different.
But with proper design a safe permanent access platform could be provided at little extra cost.
Which I do believe is what we were discussing.
 
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