small gas generator for 2 story, total of 8 units apt building

[mshields]

Involved in the design of a small, 5000 square foot apt building. Emergency lighting has been to this point, via battery packs.

Recently, while under construction, they come to realization that they're going to need a generator to back up a sump pump. And since they're going to have to put one in, they'd like to do the emergency lighting via the generator as well.

To my knowledge, if we put the emergency lighting on the generator, we'll need two ATS's and because we're in Massachusetts, MI cable for the "Emergency" function.

My question is this; we do a lot of hospitals. In 517, if you have a demand load of 150kW or less, you can go with one less ATS. I don't believe there is any such provision in Article 700. But I wanted to double check. It seems absurd to have two ATS's on what will be perhaps a 20kW unit.

Thanks,

Mike

 

[dkidd]

It is ridiculous, but unless you come under 517, you need two transfer switches.

 

[JoeStillman]

Beware of manufacturers who sell small 1Ø generators. One in particular signals the ATS from the generator rather than vice-versa. Some of their ATS's are NOT SUITABLE for Life Safety. It has an intentional time delay of 10 seconds that cannot be disabled. This manufacturer has agreements with many many electrical contractors who think they are "dealers", but who cannot supply an ATS and generator that will comply with the NEC for Life Safety. You can get products of this brand that comply, but you need to go to one of their commercial dealers, even though this is residential and probably a very small generator.

As you can imagine, I learned this the hard way by not reading the fine print on a shop drawing. It didn't say anywhere that you couldn't turn the time delay off or that it wasn't suitable for Life Safety. All it says is "programmable, 10 seconds (minimum)". The trouble was, the contractor learned the hard way too, when the inspector flunked him for too long a delay. The contractor's excuse was "Hey, I have an approved shop drawing". Even though my one line had two ATS's, one labeled "Equipment" and one labeled "Life Safety".

 

[gadfly56]

Beware of manufacturers who sell small 1Ø generators. One in particular signals the ATS from the generator rather than vice-versa. Some of their ATS's are NOT SUITABLE for Life Safety. It has an intentional time delay of 10 seconds that cannot be disabled. This manufacturer has agreements with many many electrical contractors who think they are "dealers", but who cannot supply an ATS and generator that will comply with the NEC for Life Safety. You can get products of this brand that comply, but you need to go to one of their commercial dealers, even though this is residential and probably a very small generator.

As you can imagine, I learned this the hard way by not reading the fine print on a shop drawing. It didn't say anywhere that you couldn't turn the time delay off or that it wasn't suitable for Life Safety. All it says is "programmable, 10 seconds (minimum)". The trouble was, the contractor learned the hard way too, when the inspector flunked him for too long a delay. The contractor's excuse was "Hey, I have an approved shop drawing". Even though my one line had two ATS's, one labeled "Equipment" and one labeled "Life Safety".

I'm not sure that sump pumps are considered part of Life Safety and therefore fall under either Emergency or Required Systems.

 

[qcroanoke]

I'm not sure that sump pumps are considered part of Life Safety and therefore fall under either Emergency or Required Systems.

My thoughts as well.
Somebody with the authority to call it emergency system or optional standby is who I would be talking to.

 

[JoeStillman]

...And since they're going to have to put one in, they'd like to do the emergency lighting via the generator as well.

Exactly the same scenario that led to my learning experience as well.

 

[iwire]

Involved in the design of a small, 5000 square foot apt building. Emergency lighting has been to this point, via battery packs.

Recently, while under construction, they come to realization that they're going to need a generator to back up a sump pump. And since they're going to have to put one in, they'd like to do the emergency lighting via the generator as well.

To my knowledge, if we put the emergency lighting on the generator, we'll need two ATS's and because we're in Massachusetts, MI cable for the "Emergency" function.

My question is this; we do a lot of hospitals. In 517, if you have a demand load of 150kW or less, you can go with one less ATS. I don't believe there is any such provision in Article 700. But I wanted to double check. It seems absurd to have two ATS's on what will be perhaps a 20kW unit.

Thanks,

Mike

I agree, two transfer switches needed.

Also the generator, the emergency transfer switch and the emergency electrical panelboards will need to be in their own 2 hour rated space(s) to meet MA requirements.