Gen Disco

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SeanB

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Hey everyone! I used to be a member of this board few years back. Been a journeyman for 6 years in Texas, recently relocated to New Hampshire :-? (I know I know).

So anyway, getting ready to install my first generator set. 16kw, LP on a 200 amp service (No Central AC here in New England!!).

Quick question about disconnecting means at generator. WOuld the generator's on board circuit breaker satisfy the NEC requirement for disconnecting means? (within sight).

The gen is going in the back of a house away from sight. I will be using a service entrance type ATS (NEMA 3R) which houses a disconnecting means. I am sure I need a disco where the gen is goin but..... theres one on board (have to open the hood!).

Sorry for the long post, we never did generators for homes in south texas. I worked on some 3 phase stuff years ago. Thanks for the input. (I may have a few more questions :) )
 
SeanB said:
Quick question about disconnecting means at generator. WOuld the generator's on board circuit breaker satisfy the NEC requirement for disconnecting means? (within sight).
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445.18 Disconnecting Means Required for Generators.
Generators shall be equipped with disconnect(s), lockable in the open position, by means of which the generator and all protective devices and control apparatus are able to be disconnected entirely from the circuits supplied by the generator except where both of the following conditions apply:
(1) The driving means for the generator can be readily shut down.
(2) The generator is not arranged to operate in parallel with another generator or other source of voltage.

I'd bet your genny meets these 2 conditions. Please note that "lockable in the open position" is an 08 change.

Welcome back.:)
 
Ok. Thats what I read it as. But What I want to be sure is that I dont violate the "in sight" of rule.

Since The genny will be around the corner from the service entrance, and my transfer switch will now probably be in the basement. The transfer switch has to have a disconnecting means in the basement only? SO my service entrance will be left alone, except for the sign that says

"18KW Standby system located S.W corner of property" or something like that.

I am up on the whole floating Neutral, SDS, thing :cool: I think I have my bearings straight on that. I just think its odd that there is no disconneting means at the service. I mean from the meter enclosure you would not be able to tell I had backup system (except for the sign). And the code does not specify font size, or anything for the sign. Does NFPA specify anything about it?

Sorry for all the questions, I think I read too much on the forum about generator neutrals and such :mad:
 
Well the current 200A service panel is in the basement. And from what I see that is where I can put a Nema1 ATS, while having the generator at the back of the property (out of sight from meter, and out of sight from front of house).
 
I guess what I want to know is "in sight of" WHAT should the ATS be? (In sight of utility service entrance? in sight of main service OCPD?)
 
SeanB said:
Ok. Thats what I read it as. But What I want to be sure is that I dont violate the "in sight" of rule.

Since The genny will be around the corner from the service entrance, and my transfer switch will now probably be in the basement. The transfer switch has to have a disconnecting means in the basement only? SO my service entrance will be left alone, except for the sign that says

"18KW Standby system located S.W corner of property" or something like that.

I am up on the whole floating Neutral, SDS, thing :cool: I think I have my bearings straight on that. I just think its odd that there is no disconneting means at the service. I mean from the meter enclosure you would not be able to tell I had backup system (except for the sign). And the code does not specify font size, or anything for the sign. Does NFPA specify anything about it?

Sorry for all the questions, I think I read too much on the forum about generator neutrals and such :mad:
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I am not exactly quoting code or anything, but as a guy who has installed several generators as large as 500kw, I never did get the line of sight thing. I did one generator(the 500kw), where the generator was on the roof of a high rise, the ATS sat in an electrical room only another ATS for a second generator, and the MDP and Transformer sat in a piece of switchgear outside of the structure 3 stories down. That passed the inspectors gaze. What I am getting at is no matter what the configuration or all the gear and where it has been placed, I have never had an issue with an inspector.:D
 
Ok, thats what I thought :-?

They dont do things here in New England like we do in Texas:cool:



I saw a relatively new gas station with NMSE coming right up from the asphalt feeding a large meter can, no conduit, no cement pole blocking someones bumper from BZZZZZT!
I was like WTF?!!

And they acted like they (NH state board) werent sure we texas boys were up to speed on quality craftsmanship:D Anyway I am having a good time fitting in with them yanks. Thanks a lot for the tips
 
SeanB said:
I guess what I want to know is "in sight of" WHAT should the ATS be? (In sight of utility service entrance? in sight of main service OCPD?)
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Sean, where are you reading " in site of " ? Article 445.18 requires a generator be equiped with a disconnect, with an exception that if the driving means can be shut down ( engine ), such as an emergency shut of switch/button.
 
I had a contract crew throw the line of site at me one day (regarding the service disconnect and industrial control panels). This is not in the code book is it?
 
Cody K said:
I had a contract crew throw the line of site at me one day (regarding the service disconnect and industrial control panels). This is not in the code book is it?
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Yes it is. The disconnecting means for an industrial control panel is required to be with-in site of the panel as per 409.30/430.102.
Rick
 
Generators are not that hard to work with as long as we understand a few rules that would cover other types of installations and can combined these rules together.

With the installation of a generator we will now have two different sets of conductors that are entering a building, one the service and the other feeders. This means that we will have two different set of rules that are very similar to deal with. There is also the desire to be able to have these conductors to switch back and forth automatically which imposes another problem.

Let?s first install the service and then come back and add in the back up generator and this usually makes the installation a little easier for most to understand.
The service disconnecting means and overcurrent protection must comply with the rules in 230.70 through 230.95. For the most part we have most of this done for us in a dwelling installation simply due to the equipment we buy to install.

The first rule is that the disconnect must be located outside or inside nearest the entry of a building, be readily accessible, have no more than six disconnects in which the six must be grouped together, simultaneously open all ungrounded conductors, indicate whether it is in the open or closed, have the proper rating, and is limited to eight things that can be connected on the supply side of the disconnect. All this is outlined in 230.70 through 230.82.
Second we must install overcurrent for this service which is outlined in 230.90 through 95. Overcurrent must be in every ungrounded conductor and must be an integral part of the disconnect or be located immediately adjacent and it must protect all circuits and devices with six exceptions.

A generator installed outside will have feeders that supply the building and these feeders must comply with Article 225 and once they come to the building they must comply with 225.30 through 225.39. These rules almost mirror the rules outlined for services with the exception of overcurrent devices. A disconnect must be installed either outside or inside nearest the point of entry and the disconnect must be suitable as service equipment.

In 702.11 permission is given to disregard the disconnect outlined in 225.30 if the disconnect required in 445.18 is readily accessible and located within sight of the building. If the disconnect at the generator is behind a closed door or cover it is still readily accessible but wouldn?t be within sight so then it wouldn?t fulfill the requirements on 225.30.

The transfer switch such a troublesome little item. If the transfer switch is installed on the load side of the required disconnects in 230 and 225 then there are no problems except sometimes we forget the bonding process so just keep the grounded and grounding separate and every thing is okay. This transfer switch can be located just about any where we would like to install it.

If the transfer switch is installed on the line side of either or both of the disconnects required in 230 and 225 then it is a whole different ball game. Now the transfer switch itself is required to be suitable as service equipment. To meet this requirement I look at page 332 of the 2007 UL White Book and see what criteria that this switch must meet in order to be suitable as service equipment.
In order to be suitable as service equipment the transfer switch must have means externally accessible to open both sources of power from the premises wiring.
The transfer switch when used as the service disconnect must also adhere to all the requirements outlined for service equipment such as overcurrent and bonding.
If the transfer switch is being installed on the line side of the feeders but on the load side of the service it would still have to be suitable as service equipment but would not be required to have overcurrent either as an integral part or be located immediately adjacent to the switch as this is not a requirement for feeders.

If this transfer switch is an automatic transfer and is being installed under the rules of the 2008 code cycle then the generator must be sized to carry the load imposed by the automatic transfer 702.5(B)(2). This will sure put the curb on a 16KW generator being installed on a 200 amp service with the use of full service automatic transfer, want it?
As a code enforcement official should I go out to inspect the installation of a generator with a 200 amp automatic transfer under the 2008 code, unless the generator is sized to meet the load that can be carried by the service entrance conductors there better be a load calculation present at the transfer switch or on the inspection request form or a documented means of load management or I will be making a return trip. Oh yes it will be a paid return trip.

In short what this means is without some type of load management a 200 amp service installed using either 2/0 copper service conductors I would be looking for a 42KW generator and if 4/0 aluminum I would be looking for a 43.5KW generator if a automatic transfer switch be installed for the entire service.
 
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