Who's been doing side work?

[ishium 80439]

This was kind of a toss up between putting this here and in the NEC forum. Kind of randomly I chose here as my part in this is more as an EC.

Looked at a job today where the HO had a generator installed. It is a 15KW w/ ATS. He bought it at Depot and had their recommended electricians wire it. Where to start?

~125' of 1" FMC w/ about 3/4 of outside (ie wet location). (15) 90 degree bends w/ no pull point. (3) #6 (H-H-N) and (1) #8 (G) plus 4 #14 (control). N and G were black the whole way. Breaker in the generator was a 70A. Generator feeds the main panel which is 200A rated. These are the highlights.

I told the HO that I would right up a proposal to fix this and site the code violations as I think there is clear recourse against the installing EC. W/O citing the articles (I'm feeling kind of lazy and don't feel like breaking the book out at the moment) I have 1) Too many 90's; 2) FMC in a wet location; 3) N and G not continuously marked; 4) Conductors undersized for the breaker size. I haven't calculated conduit fill yet but it "looks" OK.

Here is my question. It seems obvious to me that a 15KW generator protected at 70A is too small to run a 200A service. But the more I thought about it it seems that the only way to truly determine that is do a house calculation and see what the calculated load is. I guess we could probable also look at history from the POCO but I don't think that would count as one guy living alone is going to draw a whole lot less than if a family moves in there. It seems that this is a case where theory wins over reality.

So am I missing something or is a trip to article 220 the only way to show that this is a questionable installation?

 

[iwire]

What year NEC was the job done under?

 

[ishium 80439]

I'm not exactly sure. We are currnetly on the '08 but this could have been done under the '05. I'm not exactly sure how long ago this work was done however I would be surprised (based on visuals and other context clues) if it were done before the '05.

 

[iwire]

Before the 08 an optional generator with ATS was not required to be sized for the entire load.

Also in the 2002 and /or the 2005 FMC could be run in wet locations.

6 AWG can be used with a 70 amp breaker based on 240.4(B) but the load would have to be under 65 amps.

The (15) 90 degree bends w/ no pull point is a violation.

 

[electricalperson]

was this FMC part of a prewired generator transfer switch?

 

[K8MHZ]

I'm not exactly sure. We are currnetly on the '08 but this could have been done under the '05. I'm not exactly sure how long ago this work was done however I would be surprised (based on visuals and other context clues) if it were done before the '05.

We have this thing called 'selective loading' now that I believe allows the entire panel to be powered but having the load controlled by the HO.

The OCPD would be sized to protect the conductors under any circumstance. If so, the installation should be kosher.

 

[ishium 80439]

The FMC was definately not part of a prewired switch.

This particular installation would still violate the '05 in my opinion for a few reasons I did not state before. 1) Where attached to ATS the fitting was not weather proof allowing water to enter there (fitting was on the side of the cabinet, not underneath) and 2) the FMC is in contact with the ground in several locations in lengths over 10', also it is against a foundation that is on the down side of a hill- ie water running down the hill with the FMC as a stop before it can reach the foundation.

Point taken about 240.4(B).

The crux of the question. It appears that I may incorrect in my understanding. I always thought telling HO's "Just be careful not to turn too much on when the generator is running" was a poor idea as I've seen people yes me to death only to discover they are running everything they would ordinarily. So is it the case that we must rely on the CB in the generator to police the power usage? In the past I've always installed a sub-panel w/ preselected loads for an installation similiar to this.

 

[nakulak]

are you sure that the ec did not have the data necessary to size the feeder (220.87)

 

[brantmacga]

Before the 08 an optional generator with ATS was not required to be sized for the entire load.

Hang on Bob, I missed this.

Are you saying we can no longer install a generator serving an entire service that is sized smaller than the service?

I've done 20kw generators on 200A transfer switches; none under the '08, but you're saying this isn't allowed anymore?

If so, I'm embarrassed to say I missed that.

 

[ceb58]

hang on bob, i missed this.

Are you saying we can no longer install a generator serving an entire service that is sized smaller than the service?

I've done 20kw generators on 200a transfer switches; none under the '08, but you're saying this isn't allowed anymore?

If so, i'm embarrassed to say i missed that.

702.5 b 1&2

 

[brantmacga]

702.5 b 1&2

i'll be dadgummed.

 

[bigjohn67]

Generator Load

Generator Load

As long as the ATS is sized for 200 amps you are ok.
The generator does not have to be sized for this load as when the generator begins to "strain" the frequency will drop causing the ATS to switch back releasing the load.
Most packages sold at HD are load sheading packages.
In a load sheading package, the ats monitors the frequancy, not the amperage.
Either this will happen or the breaker in the generator will trip.
The customer will have to manage the load. More than likely if they install a natural gas generator, they have gas for water heater and cooking, so these are not a load factor.
The largest load will be the AC condenser, which these days rarely runs over 40 amps.
Suggest to the customer to install CFL lamps, even if they do not, I doubt that during a power loose they will generate more than 60 amps of load with the a/c running.

Besides, if they are selling/installing a generac unit, such as HD, the installer must be Generac certified or Generac will void the warranty.

 

[brantmacga]

As long as the ATS is sized for 200 amps you are ok. . . . .

Well that's how we always installed them, but after reading the '08 code, I don't see it as being allowed anymore.

All of the following is highlighted as a new text for the '08;

702.5(B)(2) Automatic Transfer Equipment
Where automatic transfer equipment is used, an optional standby system shall comply with (2)(a) or (2)(b).


(a) Full load. The standby souce shall be capable of supplying the full load that is transferred by the automatic transfer equipment.

(b) Load Management. Where a system is employed that will automaically manage the connected load, the standby source shall have a capacity sufficient to supply the maximum load that will be connected by the load management system.

for (a), the generator is going to have to be capable of supplying enough current for the maximum load of the service if you're transferring everything. I see that as a 20kw generator not being sufficient for a potential 30kw+ load.

and I don't think the OCPD in the generator will meet the requirements of (b).

 

[LarryFine]

It's easy enough to interrupt the HVAC's 24v to the compressor unit (summer) or heat strips (winter) when the generator starts.

The homeowner can manually shed other loads if they want to turn the HVAC back on during power outages.

 

[ishium 80439]

Besides, if they are selling/installing a generac unit, such as HD, the installer must be Generac certified or Generac will void the warranty.

I don't know that Generac would certify 15 90deg bends in a run of Greenfield that is in direct contact with the ground in multiple locations for several feet.

My point being that I'm not sure how much that certification means in this circumstance.

It seems that 702.5 may hold the answer. I only have the '05 in front of me. The '08 is in the truck. I will have to read them side by side and find out when this installation was done.

 

[brantmacga]

Besides, if they are selling/installing a generac unit, such as HD, the installer must be Generac certified or Generac will void the warranty.

Not true.


I get my generac equipment from a generac dealer/installer, and it does not void the warranty if I install it.

I'm also in the generac rebate program, so they know i'm installing them.

 

[mikeames]

for (a), the generator is going to have to be capable of supplying enough current for the maximum load of the service if you're transferring everything.

The code does not say maximum load of the service, it says

The standby souce shall be capable of supplying the full load that is transferred

Which could be 5 amps or 500 amps. If at any one time there is only a calculated load of 15kw then a 20kw generator would be fine.

 

[brantmacga]

The code does not say maximum load of the service, it says



Which could be 5 amps or 500 amps. If at any one time there is only a calculated load of 15kw then a 20kw generator would be fine.

I see it as having to be capable of serving the highest load possible.


Lets say when the power goes out, everything is running, and it transfers a load of 29kw, but the genny is only 25kw; it no longer meets the requirement.

 

[roger]

I see it as having to be capable of serving the highest load possible.


Lets say when the power goes out, everything is running, and it transfers a load of 29kw, but the genny is only 25kw; it no longer meets the requirement.

You are correct.

Using a manual transfer switch changes the rules and lets the user decide what is served.

Roger

 

[ishium 80439]

I found out that the generator was installed under the '02 NEC.

I still think that the FMC is a violation because of it's use (ie in contact w/ the ground and entering the side of a cabinet that is installed outside).

What is the verdict on the sizing of the generator. It seems that we have one camp saying it is OK because the end user can selectively shed loads and one camp saying that since it is an automatic transfer switch it can't be used because there may be a too high a load at the time of power loss.

As I wrote before it just doesn't seem right to have an under sized generator but I'm willing to learn if my interpretation is incorrect.