Clearances to Manhole Access

[buddy91082]

Hello all.

I have a manhole with 600v conductors. Looking for clearance requirements above the manhole cover. NEC does not state clearances. Could not find clearances in OSHA. I will be installing a structure over the manhole and will be limiting clearance above the manhole.

Thanks.

 

[cuky2000]

Google "confined space". Below are a couple references from the NESC and OSHA:

NESC: 370-50. General. Electric enclosures intended for personnel entry and specifically fabricated for this purpose shall be of sufficient size to provide safe work space about electric equipment with live parts that is likely to require examination, adjustment, servicing, or maintenance while energized. They shall have sufficient size to permit ready installation or withdrawal of the conductors employed without damage to the conductors or to their insulation. /sub]]

Here is a Link that may help to start your search in this matter.
[sub]

https://www.ecmag.com/section/safety/i-feel-so-confined

[/sub]

 

[buddy91082]

Thanks!

 

[LowSpark]

This is more of an architectural question. If you are putting something on top of the manhole, you will need to be able to get into and out of the the manhole without having the person get hurt. The building code has all sorts of requirements for stair landings, ladders, etc.

 

[buddy91082]

Thanks LowSpark.

It is an existing manhole located outdoors. A "container" structure is being put in place 4'-0' above the manhole cover. So there will be access spaces around the manhole cover. I guess you can say access to the cover will be in a "void space" below the container structure. Someone would have to crawl in the void space to access the manhole cover. Not ideal but I cannot find anything that states this is not acceptable. Seems to leave it to opinions/interpretations rather than a direction on clearances.

 

[bacon4life]

If there is potential for a rescue situation, 4' would not be enough space to set up a confined space rescue tripod.

 

[tinfoil]

You may want to review your locality's Occupational Health and Safety Rules.

In my jurisdiction, anyone entering a manhole needs to be wearing a safety harness with a means of hauling/winching them out of the confined space.
A Ministry of Labor Inspector would issue a hefty fine (to the business) if they caught a worker in such a place and no rescue tripod in place.
You MIGHT get away with it if you added an approved anchor point/loop on the bottom of your container structure, directly over the manhole, capable of attaching a pulley and rope, in lieu of the rescue tripod.

I would not want to be on the crew that has to lift up a manhole cover with only 4' of clearance.
Sounds like a workplace strain injury waiting to happen.
The aforementioned anchor point/loop COULD be designed to assist n lifting the manhole cover too.

I would not design it the way that you are describing.

 

[FacEngrPE]

OSHA Confined space regulations state that a confined space rescue plan must be part of every confined space entry. Manholes almost always fit all of the definitions of a confined space. Recommend reading this guidance

https://www.osha.gov/SLTC/confinedspaces/

You will almost always wind up with this, just like bacon4life suggests.

(Credit

https://www.digdifferent.com/online...0_photos_of_proper_confined-space_entry_work)

I can see this installation creating an extended outage while waiting for the obstruction to be removed to allow setting a rescue hoist.
Fred