Dedicated equipment space

[Red Wiggler]

We have a disagreement here where I work concering "Working Space" and "Dedicated Equipment Space"...

I believe that an area behind a switchboard that will not require "maintenance", or "servicing" while energized should only need a minimum working space (30"). (Hinged doors should open 90 degrees)

Others argue this same area should be selected from Table 110.26(A)(1). Either a Condition 1 or Condition 2 because of the need to "test" voltage.

If necessary I believe you would be able to test voltage from the front.

What do you think?

 

[charlie b]

For starters, I think that "dedicated equipment space" has nothing to do with your question. Secondly, many types of switchboards do not require rear access, and can be placed right up against the wall. However, if you are talking about a switchboard design that gives you the ability to open the rear panels while the board is energized, and if there is anything live in that area, then I say you need the full working clearances given in 110.26. It does not matter that you can measure voltage from the front as well. If you can do it from the rear, then the rear needs working space. I think you are leaning too heavily on the word "require."

 

[petersonra]

I think you are leaning too heavily on the word "require."

A lot of people seem to interpret the word require in this case as meaning "might be useful at some point".

My personal opinion is that it is a good design practice to allow for plenty of working space in these kind of cases, but I am not sure it is a requirement.

 

[don_resqcapt19]

Look at 126(A)(1)(a). If the equipment meets that rule, then 30" is enough. If not, you need the full work space.

 

[charlie b]

A lot of people seem to interpret the word require in this case as meaning "might be useful at some point."

110.26 takes itself out of play, if a piece of equipment is not ?likely to require? any live work. Here are several possible interpretations of ?likely to require?:
? Well, I would never work on it live, so it is certainly not ?likely to require? live work, and so therefore I don?t need working clearance.
? Anything you can do live can also be done de-energized, so it certainly does not ?require? live work, and so therefore I don?t need working clearance.
? You can get voltage readings from the back, but you can also get them from the front, so the area in back is certainly not ?likely to require? live work, and so therefore I don?t need working clearance in back.
? Company rules prohibit live work, so nothing in this plant is ?likely to require? live work, and so therefore we don?t need working clearance for any of our panels.

Here is the interpretation that I suspect most AHJ?s would embrace:
? If you can open a panel door or remove an access cover, and if after doing so you can see energized parts, then I will consider that area to be ?likely to require? live work, and so therefore I will require you to maintain working clearance.

Here is my own interpretation:
? No matter what you tell me now about company rules or personal work habits, I know that companies get sold, and personnel changes take place from time to time, and I suspect that some future schmuck of a manager will tell some poor young naive novice of an electrician to get the job done right away, and that the company cannot afford the time and expense of turning the equipment off. It is in this sense that I treat all panels, switchboards, MCCs, enclosed breakers, and a host of other stuff as ?likely to require? live work (perhaps not today or even soon, but someday), and so therefore I design the room to include working clearance.

 

[petersonra]

No matter what you tell me now about company rules or personal work habits, I know that companies get sold, and personnel changes take place from time to time, and I suspect that some future schmuck of a manager will tell some poor young naive novice of an electrician to get the job done right away, and that the company cannot afford the time and expense of turning the equipment off. It is in this sense that I treat all panels, switchboards, MCCs, enclosed breakers, and a host of other stuff as ?likely to require? live work (perhaps not today or even soon, but someday), and so therefore I design the room to include working clearance.

I think it is a wise design choice. But, I lean toward it not being a code requirement.

 

[don_resqcapt19]

Charlie,
I tend to agree that is the intent of the rule, but the words "likely" and "require" make the rule very subjective.