ACB drawing out space

[abrahamJP]

Hi,

Is there any standard or documents available to get an idea of approximate front space required
for drawing out of ACB (low voltage) like for example-for 1600A ACB ,750mm space is required
infront of switchgear.
Now I would like to know 5000A ACB, what is the minimum distance required.

Thanx in advance.

regards

Abraham

 

[waross]

That is a code issue. This is a world wide forum. Where in the world do you live??

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[abrahamJP]

I live in middle east,may be a remote place for you-but my question is beyond codes if acb depth is 450mm,what additonal
space I should allow for
1)safe working
2)is some arc/shock hazard etc come into this picture to take away precious space of
architects

regards

Abraham

 

[ScottyUK]

Identify the lift truck you need to use. A 1600A breaker can be manhandled by a couple of strong guys but not a 5000A breaker. You need room to maneuver it and operate it. Are two boards facing each other? There are a lot of considerations over and above code minimums.

 

[jraef]

I think though that the point Waross was trying to make is that the MINIMUM space requirements are often dictated by codes, so you must start there, and THEN accommodate any additional hardware requirements. In other words there is no meaningful simplistic number that can be assigned in the absence of those code requirements. Here in North America for example, the minimum number depends on a number of factors such as the voltage level to ground, the material conductivity of the opposing surface, etc. etc. If you apply an arbitrary number without taking those things into consideration, even if you THINK it should be acceptable, you may find yourself in violation of a code or law that applies in your jurisdiction, wherever that may be.

I have no idea what code that would be in your un-named "middle east" country, but my experience is that code requirements such as this tend to be very similar across the world, chiefly because they are modified over time due to investigations over accidents, and those reonsible will look to other codes to find what appears to work best.

"Will work for (the memory of) salami"

 

[ScottyUK]

Yeah, I got that jraef. Designing to code - i.e. using it as a design guide, as some do - can lead to code-compliant but totally unworkable solutions. Code is a minimum as you have already said, after that it needs to be workable too.

 

[davidbeach]

Back when I was designing those kinds of installations, I always figured that if the inspector ever had to get out a tape measure to check clearances that there was insufficient clearance, even if it met code.

 

[abrahamJP]

Thanks for all thoughtful replies-It helps to gain a partial understanding of subject.

My thinking was this code design was based on old acb standards-not either on considering new electronic trip units or "maximum power,minimum volume concepts" prevalent in switchgear industry.Still question remains- is codes considers the worst case of lv circuit breaker rated acbs,ie 6300A+other consideration I just learned from experienced people like you

regards

Abraham

 

[jraef]

There were some considerations given to a few aspects of working clearances when vacuum breaker technology developed to displace ACBs, mainly because rear access for bus connections was no longer necessary in some designs. But the working distances in front of gear always has to do with not creating hazards for anyone who happens to be in front of it doing tasks related to the gear.

"Will work for (the memory of) salami"

 

[rcw retired EE]

If you have ever had to postion a breaker truck in front of switchgear with a 4,000A breaker in tight quarters with the door swinging open partially in the way and a 10mm clearance from the control panel to the back of the truck you would know to add extra room. Manufacturer's drawings give the minimum space needed to pull out the breaker, but they do not usually give the distance needed to swing the breaker in a 90 degree turn with enough room to get behind the truck and roll it towards the switchgear. It is like parallel parking a car in a spot that is 100mm longer than your car. On paper the car will fit.

I add a meter + to the space given in manufacturer's literature.

 

[ScottyUK]

If you want rough figures, I'd allow an absolute minimum of two metres clear space in front of the gear assuming an average-sized lift truck. Three metres would be better, if you have the space to accommodate it. Get in to a switch house and try maneuvering a laden lift truck and see for yourself.

 

[Padlock01]

Normally the switchgear manufacturer will have guidelines on the withdrawal requirements for such a breaker. I normally allow a space of 2,5 metres in front of a HV switchboard with a incomer of 3000amp.
Yours in Safety.