where equipment is required to have front and rear access (switchboards / switchgear) if you have double the required working space in front of the gear only one entrance / egress door is located in the "front" of the gear outside the working space. the question because the door is on the "front" side of the gear is double working space also required at the back of the gear or is it acceptable to have only 1x working space? (it was my thought that 2x would be required also on the working space behind the gear). just wanted to get your thoughts..
working space (2x)
- Thread starter Mike01
- Start date
- Status
- Location
- Lockport, IL
- Occupation
- Retired Electrical Engineer
I agree with you. Each working space has to be treated separately.
makes sense to me...
makes sense to me...
Thanks, we were having a discussion in our office and some were saying if you have 2x in front than you only need 1x in the rear of the equipment even if the only door is in the front my thought was it is the same hazard regardless, just because you have 2x in the front how does that make 1x at the back ok??
110.33(1)(b)Extra working space "It shall be located so that the edge of the entrance is not less than the minimum clear distance specified in table 110.34(A) for equipment operating at that voltage and in that condition" makes it clear to me.
makes sense to me...
Thanks, we were having a discussion in our office and some were saying if you have 2x in front than you only need 1x in the rear of the equipment even if the only door is in the front my thought was it is the same hazard regardless, just because you have 2x in the front how does that make 1x at the back ok??
110.33(1)(b)Extra working space "It shall be located so that the edge of the entrance is not less than the minimum clear distance specified in table 110.34(A) for equipment operating at that voltage and in that condition" makes it clear to me.
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- Location
- Lockport, IL
- Occupation
- Retired Electrical Engineer
There are some who would argue that thermographic surveying, a task that must be done live, would put you into the realm of 110.26 requirements.
That makes sense. It wouldn't do much good to do thermographic surveying with the power off
Steve
WastefulMiser
Senior Member
- Location
- ANSI World
I don't have the NEC in front of me ... but I was under the impression you only need 30" behind equipment with rear access. Something about parts requiring "adjustment", etc. only requires Condition 1-3 working clearances.
Now, I believe there should be two means of exiting behind the equipment 6' and longer and 1200A or greater.
Now, I believe there should be two means of exiting behind the equipment 6' and longer and 1200A or greater.
Pierre C Belarge
Senior Member
- Location
- Westchester County, New York
How many times have we seen equipment installed with the backside up against the wall?
There is no 'one size fits all", in regards to equipment.
One needs to review the applicable portion of 110.26, and read the installation instructions sent with the equipment from the manufacturer.
There is no 'one size fits all", in regards to equipment.
One needs to review the applicable portion of 110.26, and read the installation instructions sent with the equipment from the manufacturer.
WastefulMiser
Senior Member
- Location
- ANSI World
Pending the OP's application I do not see in the NEC 2008 where it requires 2X behind equipment that does not contain renewable and adjustable parts. Enlighten me. It seems purely subjective.
It may be good design practice to provide, but highly impractical ($$$) in some circumstance where space is limited. Architects despise power and control rooms.
- Location
- Massachusetts
There are many switchgears that have rear covers that are not required to be accessible
Pierre C Belarge
Senior Member
- Location
- Westchester County, New York
I am not sure if you have an issue with the comment I posted. In the post, I was not stating it is necessary at all times to have space on both the front and back of gear.
ohmhead
Senior Member
- Location
- ORLANDO FLA
Well this requires front and rear access kinda
But on most low voltage gear with screw covers on the back its kinda on the wall you never go back thur the back even when you test you do it from the front the gear is bigg enough inside to test busses hot .
But before you put it on that wall check your buss duck tap connections some need to be installed before you slide it in place or you cant get to the nuts and bolts .
Thats when you helper with long arms becomes your best friend !
But on most low voltage gear with screw covers on the back its kinda on the wall you never go back thur the back even when you test you do it from the front the gear is bigg enough inside to test busses hot .
But before you put it on that wall check your buss duck tap connections some need to be installed before you slide it in place or you cant get to the nuts and bolts .
Thats when you helper with long arms becomes your best friend !
Pierre C Belarge
Senior Member
- Location
- Westchester County, New York
Nice equipment!!!
I have inspected more and more of this type of installation. Yet, most installations are not of medium voltage brought to a building. The majority of work I see is either 480Y, or 208Y. Most of those systems do not require accessibility to fuses/terminations from the rear of the equipment, hence installation up against the wall.
I have inspected more and more of this type of installation. Yet, most installations are not of medium voltage brought to a building. The majority of work I see is either 480Y, or 208Y. Most of those systems do not require accessibility to fuses/terminations from the rear of the equipment, hence installation up against the wall.
30" working space
30" working space
the only place i can find the 30" requirement is in 120.26(A)(1)(a) and it refers to "dead front" construction where "rear access is required to work on non electrical parts" but even in 480V switchboard some require rear acess for conductor termination, infra red scanning (live parts exposed). 110.26(C)(2) talks about large equipment and that there shall be one entrance to and egress from "the required working space" in this cas the front and rear of the equipment (in my opinion I may be wrong would not be the first time and definatly not the last) then you would look at the two exceptions if there is a clear and unobstructed way of egress (again here some say one at each end or opposite wall due to the fact if you are working on the "middle section" and there is an incident the pat to the egress would be obstructed by the incident and the clear and unobstructed path would be the opposite wall) define "unobstructed" or double the working space if you provide double the space in front and only 30" behind the gear creates an obstruction to the egress??
30" working space
the only place i can find the 30" requirement is in 120.26(A)(1)(a) and it refers to "dead front" construction where "rear access is required to work on non electrical parts" but even in 480V switchboard some require rear acess for conductor termination, infra red scanning (live parts exposed). 110.26(C)(2) talks about large equipment and that there shall be one entrance to and egress from "the required working space" in this cas the front and rear of the equipment (in my opinion I may be wrong would not be the first time and definatly not the last) then you would look at the two exceptions if there is a clear and unobstructed way of egress (again here some say one at each end or opposite wall due to the fact if you are working on the "middle section" and there is an incident the pat to the egress would be obstructed by the incident and the clear and unobstructed path would be the opposite wall) define "unobstructed" or double the working space if you provide double the space in front and only 30" behind the gear creates an obstruction to the egress??
ohmhead
Senior Member
- Location
- ORLANDO FLA
Well Mike01 take a look at the switchgear in the back corner in this room you cant see it clearly but its the best i could fine for you sorry .
A example of clear space issues ,the inspector said if this was 2008 he would need a door in that back space . Your looking at the greenlee wire feeder and the ladder in that back space thats were the two are located.
This room is bigger its 50ft by 27 ft with two double doors you cant see now. If you like i can show the rest ?
thers two 4000amp buss switches back there each 48 x48 sq with 6 foot in front there closed in by 3 walls no way to get out but each one alone is not more than 6 foot long so he passed the job .
But said if it was 2008 he would not pass it !.
This is were the plans designed this and we had no choice on location .
A example of clear space issues ,the inspector said if this was 2008 he would need a door in that back space . Your looking at the greenlee wire feeder and the ladder in that back space thats were the two are located.
This room is bigger its 50ft by 27 ft with two double doors you cant see now. If you like i can show the rest ?
thers two 4000amp buss switches back there each 48 x48 sq with 6 foot in front there closed in by 3 walls no way to get out but each one alone is not more than 6 foot long so he passed the job .
But said if it was 2008 he would not pass it !.
This is were the plans designed this and we had no choice on location .
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