Physical Damage Protection for Elec. Vehicle Charging Station in Ex. Parking Garages

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ChargedUp

Member
Location
Ohio
Per NEC 110.27(B), electrical equipment that can be exposed to damage must be protected by enclosures or guards.

For electrical vehicle charging stations and associated electrical equipment being installed in existing parking garages on elevated decks, my opinion is that bollard protection is an acceptable method.

However, IBC Section 1607.8.3 says vehicle "barriers" must resist a concentrated load of 6,000 lbs.

How can the NEC and IBC applicable code sections be applied together to determine best design practice?

Adding a bollard (or any type of guard for that matter) capable of resisting a horizontal force of 6,000 lbs in an existing parking garage will most likely affect the concrete deck integrity if actually hit with a force of 6,000 lbs. I.E. an anchored bollard/baseplate design, typical design seen in most garages.

My opinion is to install bollards with small, shallow anchors in front of the electrical equipment that acts as a deterrent and adds some protection to the electrical equipment when hit at slow speeds. These bollards would be designed to fail under a certain load condition as to not affect concrete deck integrity.

What are your thoughts?
 

MAC702

Senior Member
Location
Clark County, NV
What is the definition of a "vehicle barrier?" Does the protection of the electrical equipment need to meet the standards of a "vehicle barrier," which may be something far greater for preventing a vehicle from driving off an elevated surface, or something like that.
 

ChargedUp

Member
Location
Ohio
Based on what I found, vehicle barrier is more to prevent a vehicle from falling out of the parking garage, and all the IBC says is vehicle barrier. The NEC says equipment must be protected. So how do you interpret the two different codes to line up with one another and come up with a design that will provide protection to the public and also meet all applicable codes?
 

drcampbell

Senior Member
Location
The Motor City, Michigan USA
Occupation
Registered Professional Engineer
A short curb could be installed on the floor, far enough ahead of the charger that it would stop a tire before the vehicle body demolished the charger. I don't think that would compromise the deck's structural integrity, no matter how hard it was hit.

Or maybe a short stub of chain-link fence that extends well above eye level. It wouldn't physically stop a vehicle but would be a strong psychological barrier.
 

ChargedUp

Member
Location
Ohio
Thanks for the response. We also thought about that, and but in my opinion an electrical plan reviewer would prefer bollard over curb. What the electrical plan reviewer doesn't know (or maybe he does) is that the bollard is not designed to resist a 6,000 lb horizontal force.

The issue at hand is almost beyond plan review, and more about safety of public, and liability issues if someone was to crash into the equipment.
 

retirede

Senior Member
Location
Illinois
Thanks for the response. We also thought about that, and but in my opinion an electrical plan reviewer would prefer bollard over curb. What the electrical plan reviewer doesn't know (or maybe he does) is that the bollard is not designed to resist a 6,000 lb horizontal force.

The issue at hand is almost beyond plan review, and more about safety of public, and liability issues if someone was to crash into the equipment.

It seems to me that the 6000 lb horizontal force requirement needs to be supplemented with the specification of the height (distance from the mounting surface) at which the force is applied.

A given design that withstands 6000 lb applied 6” from the deck may fail if the 6000 lb is applied 3’ above the deck.

Perhaps it is implied that it must withstand 6000 lb at the full height of the bollard?
 

ChargedUp

Member
Location
Ohio
ASCE 7-10 section 4.5.3 says that the 6000 lb load on vehicle barrier systems shall be assumed to act at heights between 1'-6" and 2'-3".
 

MAC702

Senior Member
Location
Clark County, NV
Based on what I found, vehicle barrier is more to prevent a vehicle from falling out of the parking garage, and all the IBC says is vehicle barrier. The NEC says equipment must be protected. So how do you interpret the two different codes to line up with one another and come up with a design that will provide protection to the public and also meet all applicable codes?

How is the NEC saying that the equipment protection must meet the standards of the IBC's "vehicle barrier?" Does the IBC require a "vehicle barrier" at electrical equipment? If not, than only your AHJ needs to approve what is protective of the electrical equipment, per the NEC, and they should not be using the standard of a "vehicle barrier."
 

ChargedUp

Member
Location
Ohio
@ChargedUp
If bollard protection is acceptable in your opinion, why shouldn't it be in the opinion of the AHJ?

The opinion of the AHJ will always steer the direction that we need to go. For one particular site, the AHJ is indicating that bollard protection for electrical equipment must meet the "vehicle barrier" standards of the IBC.

So we took a deep dive to determine if our current practices meet NEC/IBC requirements for electrical equipment protection via bollards for all sites, not just ones that the AHJ raise a fuss about.
 

drcampbell

Senior Member
Location
The Motor City, Michigan USA
Occupation
Registered Professional Engineer
... the bollard is not designed to resist a 6,000 lb horizontal force.
The issue at hand is almost beyond plan review, and more about safety of public, and liability issues if someone was to crash into the equipment.

This started me thinking about pad-mounted transformers, which contain 15 kV on one side and are often adjacent to the parking lot, just a curb-hop away from a motor-vehicle crash.

It seems to me that it's possible to design a bollard that will both sustain a 6000-pound horizontal force and limit the amount of damage done to the deck by specifying large-enough baseplate (to reduce leverage) and fasteners with a small-enough diameter and a predictable pull-out force.
(full disclosure: I am an engineer, but not a structural engineer)
 

ChargedUp

Member
Location
Ohio
Totally agree its possible, but is it practical/feasible to install? The amount of anchors required will need to miss any existing reinforcement & stressing tendons as well. The baseplate will need to be around 18" diameter or 18" square. All the bollards with baseplates I've seen in garages have small plates with (4) anchors. That's not saying we SHOULD'NT reinvent the wheel and design something that will actually protect the electrical equipment rather than something that is more like warning signage than anything else. Just wanted to hear the Mikes Holt majority thoughts on a best practice...

So now that all the questions have been asked, what would be the majority vote?

Bollard w/ small baseplate (4 anchors) designed to fail under a given load to not affect deck integrity

or

Bollard with large baseplate (18" diameter) and (8) anchors designed to resist 6,000# horizontal force
 

gadfly56

Senior Member
Location
New Jersey
Occupation
Professional Engineer, Fire & Life Safety
Mounting Height

Mounting Height

Wouldn't it be possible to mount the breakable bits of the charger at a height above the hood/rear of the car but with the connector accessible for plugging into the vehicle? As I recall, you don't really "turn on" the charger, all the smarts are built into the connector, so you wouldn't need access to the body of the charger.
 

ChargedUp

Member
Location
Ohio
Wouldn't it be possible to mount the breakable bits of the charger at a height above the hood/rear of the car but with the connector accessible for plugging into the vehicle? As I recall, you don't really "turn on" the charger, all the smarts are built into the connector, so you wouldn't need access to the body of the charger.


Yes it would but that equipment is designed by others and I'm speaking more of the upstream equipment that actually supplies power to the chargers.
 

gadfly56

Senior Member
Location
New Jersey
Occupation
Professional Engineer, Fire & Life Safety
Yes it would but that equipment is designed by others and I'm speaking more of the upstream equipment that actually supplies power to the chargers.

OK, that wasn't clear to me from your original post. I know that space is usually at a premium in parking decks, but what about an energy absorbing crash barrier, like the barrels of sand/water or collapsible barriers you see on the highway?

QuadGuard_large.jpg

Impact react350II-1.jpg

There is a short Wiki on this here. I assume we're not dealing with highway speeds on a parking deck, so the systems can be more limited than for a 65 MPH highway.
 

Barbqranch

Senior Member
Location
Arcata, CA
Occupation
Plant maintenance electrician Semi-retired
This weekend I was driving by the local mall that has a Tesla charging station out front (IIRC 8 or 10 stations). They only had plastic bars, maybe 4 inches tall, to stop the cars.
 

MAC702

Senior Member
Location
Clark County, NV
This weekend I was driving by the local mall that has a Tesla charging station out front (IIRC 8 or 10 stations). They only had plastic bars, maybe 4 inches tall, to stop the cars.

Curious: Who pays for the power? Do you swipe your credit card when you plug in? Are we giving free power to those who drive electrics? I've no idea.
 
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