NEC Code for Protecting Transfer Switch

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Another C10

Another C10

Electrical Contractor 1987 - present
Location
Southern Cal
Occupation
Electrician NEC 2020
Bare with me on this,

I have a Generator Vendor that said he usually intercepts the load side of the utility meter to supply voltage to his transfer switch, granted upstream of the main breaker might I add, to feed either a 100A-200A transfer switch ( depending ) which then in return refeeds through the main breaker of the metered panel to the various branches of the distribution panel, I told him that's illegal, mentioning there would be no way to ever disconnect the supply utility voltage at the Transfer Switch.

Thanks to you folks I've been more in tuned to searching the code book regarding these kinds of disputes, just got my latest 2020 book.

I found Articles 405.13 .... mentioning over current protection then I went to 240.21 ( B) Load side of feeder protection and ended at 240.21 (B) (2)

My question to the code experts is, is there a better code reference relating to this vendors mentioned technique of intercepting a utility voltage before the distribution. Keep in mind, I only feed a transfer switch with a properly sized breaker to feed a separate sub panel for the intended selected branch circuits.

Hope I didn't get too lengthy, just wanted to create a full visual.
 
tom baker said:
If he/she is installing a service entrance rated transfer switch then that is allowed
Click to expand...
I'll look that up , I'd think it would have to be a type of all in one meter section with Transfer switch included. This is a separate transfer switch that needs a utility supply , Generac 1000001165.
 
If this is legal, I cant imagine that utility is ok with their power reference being utilized at a second distant location before the service main.
 
You can tell your vendors that there is no circumstance where a non SUSE rated switch can be connected to service conductors. This is an NEC and UL requirement and has been for decades.
Article 405? and Article 240 are not relevant to this.
 
Their claim was that the thermal breaker of the Transfer switch was sufficient. I said no not legal. actually very dangerous as well.
 
Forgive my ignorance on the variety of transfer switches, Its basically automatic that detects when utility voltage is present or not allowing the generator to kick in. They use the Generac 1000001165.
 
I guess I was under the impression that the only place electricians are not legally allowed to intercept a utility source is within the meter section, the bussing down stream of the meter after the main is fair game.
 
Well, I've looked into the service rated ATS and my question then would be if servicing how would one ever replace any elements within the enclosure involving a line voltage without pulling the meter or having utilities turn off the property transformer.
 
A service entrance rated ATS will always have line voltage within (just like a service disconnect) unless you pull the meter, which in most cases means getting the utility involved.
 
Resized_20191105_201247.jpg

# 10000011659 Generac


Is there a code reference allowing a raw utility feed to go to a personal piece of property like an ATS before hitting a Meter Main.
 
Another C10 said:
View attachment 2551977

# 10000011659 Generac


Is there a code reference allowing a raw utility feed to go to a personal piece of property like an ATS before hitting a Meter Main.
Click to expand...
This switch is rated SUSE as shown right on the label. It can be installed after a meter and be used as the service disconnect.
You mention a meter/main. That presents other issues as then the ATS must be installed after the main as you can't modify the meter/main internally. If you have a meter/main then you don't need a SUSE rated ATS.
Now if that meter/main also has all the branch circuits in it that you are trying to put on the genset then you will have to redesign the service.
 
Rough Diagram showing my concern for liability

Didn't bother with neutrals or other obvious elements missingUntitled.jpg
 
In reading your posts I get the sense that you or your vendors are saying to install the ATS in between the meter and the main of a factory built meter/main combo device. This can't be done in a code compliant manner for a number of reasons regardless whether the ATS is service rated or not for a number of NEC and listing issues.
We just had a very similar thread to this not long ago (also California). Maybe someone will find it and put a link.
 
Another C10 said:
Rough Diagram showing my concern for liability

Didn't bother with neutrals or other obvious elements missingView attachment 2551978
Click to expand...
Ok, this is what I thought you are saying as I said in my post #18 that I posted before I saw this post. You can't do this and be compliant with the NEC or listing requirements. You mention that neutrals are not shown-I get that, but that is a big part of the code and listing issues with trying to do this.
For starters that meter/main will have a permanent factory neutral bond and you will end up with neutral bonding downstream the the ATS main ( that is now the service disconnect).
 
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