NEC Required Access at Equipment. Is it ALL equipment.

[rcw retired EE]

NFPA 70 requires a 30" wide x 36" deep by 78" tall clear working space in front of electrical equipment operating at <150V to ground where it is "likely to require examination, adjustment, servicing, or maintenance while energized".. (The depth is 42" for 151V-600V).

We ran into problems trying to design this large of an access for Motor Operated Valves (MOV's) on steam lines and other piping. The motor controls are mounted in the valve motor assembly, along with the myriad limit switches, torque switches and accessories used to operate the valve. The problem is the valve location in pipe racks and pipe runs makes providing this space problematic.

How do you comply with this? Some options:
Have a policy of no work on the valve unless it is de-energized?
Place a disconnect immediately adjacent to the valve to make it easier to de-energize?
Spend the significant extra money to route the 16" steam line to a location where access is available? (Plus adding the steam traps and drains needed).
Provide "reasonable" access for connecting and repairing, but not the full 30" x 42" x 78" space?

These control enclosures are not a panel with a swing door and a well defined "front" access space. Most MOV controls are ultra compact and are crammed under a round cover with access to terminals from all directions. The motor and enclosure are usually mounted so we get to straddle the pipe to work on it.

Most installations that I've seen have OK access, a few are terrible, and a few meet the letter of the code. What is your experience.

 

[RonShap]

NFPA 70E and OSHA require you to consider equipment energized unless you have tested it and proved it is de-energized and locked out.
Most inspectors consider NEC Section 110.26 "likely to require examination, adjustment, servicing, or maintenance while energized" to be line voltage and required intervention regularly such as fused switches, etc. Generally I've seen controls being overlooked, but there isn't anything in black and white. You need to consult with the local authority having jurisdiction regarding how they interpret the requirement.

Ron

 

[racookpe1978]

Put the MOV and motor controller terminal boxes where needed with the best-available safe access (You should not have to straddle a pipe to get into the terminal box). Be able to isolate that terminal box (the MOV power supply) from a standard NEC-accessible small cut off box that might be on the floor or back away from the valve itself.

 

[jraef]

At a former employer, we had almost this exact same discussion, except with regard to motors buried deep inside of machines. As it was later determined, there is a subtlety to this that you may be missing:

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 comply with the dimensions of
110.26(A)(1), (A)(2), and (A)(3) or as required or permitted
elsewhere in this Code.

If there is no need to service the equipment WHILE ENERGIZED, then the clearance issues are not applicable. So if, for example, the equipment is a motor, and you cannot normally service the motor while energized (hence a LO/TO requirement), this does not apply. So I can only imagine that MOVs would follow that rule; you must disconnect and lock out the power prior to opening any live electrical areas of it.

Whether or not, in practice, someone chooses to VIOLATE that LO/TO rule whether out of disregard or necessity, that does not mean you must DESIGN the access space require for that.

"Will work for (the memory of) salami"

 

[rcw retired EE]

Thanks for the ideas. They are the same ones we have been discussing internally. We are writing a new design standard and included the 30" x 36" x 6'6" access area for MOV's. Of course, the piping and layout groups don't like that restriction and are looking for options.

 

[BJC]

Motor operated valves are electrically powered but not electrical equipment.
I seen, tested and set limits on MOVs in the most difficult places. Sometimes it took scafolding, ladders etc to access the valves. Teh people who design piping systems don't usually design to NFPA anything.
If it's a powerplant your working on the NEC doesn't necassarly apply.