Ambulance Connected to Building Via Cord and Plug

[iwire]

That's exactly the argument the dealers and sales are trying to give us. I totally agree that the vehicle is not covered by the NEC, except for the fact that it is plugged in using a cord-and-plug connection, .

What words in 90.2 support that claim?

None.

 

[iwire]

The NEC ends at the outlet.

Does it? The NFPA seems less convinced of that

A few examples.

422.44 Cord-and-Plug-Connected Immersion Heaters. Electric heaters of the cord-and-plug-connected immersion type shall be constructed and installed so that current-carrying parts are effectively insulated from electrical con-tact with the substance in which they are immersed.

422.45 Stands for Cord-and-Plug-Connected Appli-ances. Each smoothing iron and other cord-and-plug-connected electrically heated appliance intended to be ap-plied to combustible material shall be equipped with an approved stand, which shall be permitted to be a separate piece of equipment or a part of the appliance.

422.46 Flatirons. Electrically heated smoothing irons shall be equipped with an identified temperature-limiting means.

422.47 Water Heater Controls. All storage or instantaneous-type water heaters shall be equipped with a temperature-limiting means in addition to its control ther-mostat to disconnect all ungrounded conductors. Such means shall comply with both of the following:

(1) Installed to sense maximum water temperature.

(2) Be either a trip-free, manually reset type or a type hav-ing a replacement element. Such water heaters shall be marked to require the installation of a temperature and pressure relief valve.

Exception No. 1: Storage water heaters that are identified as being suitable for use with a supply water temperature of 82°C (180°F) or above and a capacity of 60 kW or above.

422.34 ARTICLE 422 — APPLIANCES

 

[ActionDave]

Does it? The NFPA seems less convinced of that

A few examples.

Power hungry types that they are.

 

[iwire]

Power hungry types that they are.

Your view, mine is not the same.

 

[jvacierto]

people make all kinds of bad decisions when they buy stuff and don't get what actually meets their needs. That is not the fault of the designer. it is the fault of the guy that bought it for not buying what he actually needed.

if you were to break it up into 2 120V branch circuits inside the ambulance, how would you prevent them from plugging it into the same 8A invertor, or into two receptacles that are on the same circuit?

We have a small, 2 or 4 breaker load center in the ambulance, with one of the breakers being wired as a GFCI main breaker for the load center. We have considered breaking the power into (2) 120V circuits, and we do that when we have high amperage equipment that requires a separate feed (space heater, medical air compressor, etc.). But again, even when we do that, we run into the issue that the inverter transfer power to the shoreline and the inverter essentially goes away when the shoreline is plugged in.

 

[jvacierto]

My refrigerator or my relocatable power tap (power strip) does not comply with the NEC, they have their own UL standards to follow.

Similar for the ambulance.

The worst that will happen is the breaker will trip.

Ambulances have codes they need to follow. KKK, NFPA, and AMD are the main ones we have to adhere to, and both KKK and NFPA require the 125V outlets to be wired to the NEC.

 

[jvacierto]

Unless there were a way to limit the load on all 11 receptacles to stay below 20 amps the number of receptacles is irrelevant. I could easily overload a 20 amp circuit with a single duplex receptacle connected to it.

I replied earlier that we do have a load center in the ambulance with a main 20 amp breaker and sometimes a dedicated circuit for other equipment. But again, the issue is the inverter transfers power to the shoreline when it is plugged in, so depending on how we have the inverter wired, we may or may not be able to rely on the load center breakers.

 

[jvacierto]

The NEC ends at the outlet. Effectively your ambulance is simply end use equipment, like a appliance.
You rationale of 'it is plugged therefore the NEC applies' goes completely against many code sections, in particular 110.3(B) and 110.26. Is your ambulance Listed or Labeled? Do you maintain 30" of width in front of electrical equipment that needs servicing like your inverters.

I had written a reply earlier that ambulance codes, KKK and NFPA, reference the NEC for proper wiring and placement of receptacles, especially section 210 part III. Inverters obviously aren't required to meet codes other than UL and manufacturer codes, but the receptacles must meet NEC.

 

[jvacierto]

Yes.

The NEC does not apply to the ambulance regardless of it being connected to shore power

Same for watercraft or appliances.

Just because you wire up a listed appliance to a building does not mean the NEC applies to the internal wiring.

But ambulance codes like KKK and NFPA require the 125V system to meet NEC, so we do have to follow it. The ambulance industry isn't the same as the automotive industry, it's a special niche with both 12V and 125V systems, so we need to meet multiple codes.

 

[jvacierto]

Does it? The NFPA seems less convinced of that

A few examples.

Thank you, and like I have been replying, KKK, NFPA, and other ambulance codes specifically cite NEC as the code to follow for certain aspects of the 120V system, such as the receptacles and grounding. No matter how much people argue the NEC doesn't apply on its own, other codes do apply the NEC to the ambulance.

 

[jvacierto]

What words in 90.2 support that claim?

None.

It's not in the NEC, but KKK calls out the NEC for requirements. Please see attached sections KKK 3.7.8.2 and 3.7.8.3.

 

[jvacierto]

So can I but I think I would start with a bigger inverter. Then maybe seperate circuits for critical and noncritical use. The AC going out probably won't kill you.

We do offer bigger inverters, so that part is more of a sales issue. The main problem is the fact that customers are asking for more outlets than we are comfortable giving them. KKK and other ambulance codes don't offer any guidance in load calculations for the receptacles, but they refer to section 210, and I would rather be conservative in calculating receptacle loads than not. If a medical air compressor is being used on the AC for some medical reason and it goes out and kills a patient, I want to know we did everything we could in the design to prevent it from going out.

 

[iwire]

It's not in the NEC, but KKK calls out the NEC for requirements. Please see attached sections KKK 3.7.8.2 and 3.7.8.3.

Actully those sections support the consensus that the NEC does not apply except the sections specifically called out by the documents you posted.

I understand, your heart is in the right place, you are trying to make do a quality job.

But we can't make the NEC apply where it does not.

 

[mgookin]

Actully those sections support the consensus that the NEC does not apply except the sections specifically called out by the documents you posted.

I understand, your heart is in the right place, you are trying to make do a quality job.

But we can't make the NEC apply where it does not.

Let's assume the NEC does not apply since that debate seems to be derailing the fact the man wants to build a quality product.

With all these smart people on here, how can we help him build a better ambulance?

 

[iwire]

Let's assume the NEC does not apply since that debate seems to be derailing the fact the man wants to build a quality product.

hmy:

We are derailing the OPs thread by talking about the OPs question?

So my question is, am I being too strict in my application of the NEC to the cord-and-plug branch circuit feeding the ambulance?

As far as your own question about how we can help build a better ambulance I don't think we can. We are not signing the checks.

 

[mgookin]

hmy:

We are derailing the OPs thread by talking about the OPs question?

It seems like we're beating a dead horse on whether the NEC applies and detracting from the underlying objective of solving his problems.

 

[growler]

Both the other electrical engineer and I are definitely concerned with the onboard inverter or generator. We are already on the border of safety with the (11) 125V outlet maximum limit we have given to sales. However, our ambulance dealers want to put in as many as 15 outlets or more in the ambulances and unfortunately there is no receptacle limit called out in ambulance codes, such as KKK and NFPA. Sales is asking why we can't put in more outlets. Thus, we have to fall back on the NEC, since the inverter usually transfers to the building power when the shoreline is plugged in and we can argue we are trying to protect the cord-and-plug connection from overcurrent from the building.

So the problems is sales VS engineering.

The sales dept. wants more receptacles because that's more money (makes the customer happy) and engineering thinks that may cause problems. Sound more like a design issue than a code issue.

I would try to collect data from within the industry. There is competition, so what are the other guys doing and how have they solved the problem?

 

[mgookin]

So the problems is sales VS engineering.

The sales dept. wants more receptacles because that's more money (makes the customer happy) and engineering thinks that may cause problems. Sound more like a design issue than a code issue.

I would try to collect data from within the industry. There is competition, so what are the other guys doing and how have they solved the problem?

That's a very common problem across many industries.

Sales and marketing want to sell what does not exist, then the engineers need to make it happen. And if it doesn't work, who do you think gets blamed? OP gets thrown under the bus (no pun intended)

 

[growler]

That's a very common problem across many industries.

Sales and marketing want to sell what does not exist, then the engineers need to make it happen. And if it doesn't work, who do you think gets blamed? OP gets thrown under the bus (no pun intended)

The product may not exist, I'm not familiar with the ambulance industry. If the competition offers a model with what the customer is looking for and they have solved the problem that would put sales at a disadvantage.

If you are going to only sale yesterdays product then why do you need engineers? They are under the gun but that's the work they chose.

 

[petersonra]

But ambulance codes like KKK and NFPA require the 125V system to meet NEC, so we do have to follow it. The ambulance industry isn't the same as the automotive industry, it's a special niche with both 12V and 125V systems, so we need to meet multiple codes.

since the NEC says the ambulance is not covered by the NEC, you are following the ambulance code by completely ignoring the NEC inside the ambulance.