Query: Auto Transfer Switches

[jhc]

Many home generator sets, particularly Generac, in 10kw & up categories, according to catalogs, come with automatic transfer switches. Most also seem designed (without having one to examine), to feed individual circuits rather than the entire panel. Questions:
1. Can such auto switches be modified to feed entire panel by removing all smaller breakers and substituting 2 100 amp/240 breakers to be the only two coming off the bar if genset is powerful enough? (I realize homeowner would have to be "selective" to avoid genset overload in such case.)
2. Are such switches inserted BETWEEN main house feed and panels, or does an electronic sensor merely kill genset when utility power is restored? NEC code?? Question also relates to physical size of home feed lines that would seem to be too large to even install in the transfer switch boxes (according to photos & no listed sizes).

[ August 05, 2005, 07:27 PM: Message edited by: jhc ]

 

[augie47]

Re: Query: Auto Transfer Switches

There are a number of Generac installations in this area. The installations vary from small units for a limited number of circuits selected from an existing panel, to mid size units which automatically transfer selected loads in a sub-panel, to "whole house" which transfer the entire
house panel. A majority automatically transfer the loads from utility to generator as needed, and the reverse as needed, as well as automatically test run the unit, charge the batteries, etc.
There are a number of rather detailed and potentially dangerous items that need to be addressed in each installation; proper sizing of the unit, proper grounding, proper overcurrent protection, prevention from "back feeds" to utility lines, proper start up of the unit to check voltages, frequency, etc, to name a few.
Having seen the evil result from some DYI installations, I would strongly suggest you contact an authorized Generac dealer and/or a electrical contractor to assist you.

 

[charlie tuna]

Re: Query: Auto Transfer Switches

jhc,
a normal transfer switch in commercial buildings will feed the building's critical panels and equipment. these panels and equipment are listed as emergency power and the transfer switch is designed and sized to feed these loads. in a residence, there loads are not separated and to maintain the generator's size to a minimum they design a separate panel to allow the customer to connect loads that they consider emergency equipment and do not exceed the design full load rating of the generator set. a home owner can have the entire service back up power supplied by a generator set but it will be very large and expensive. the generac units are set up as a package unit for the average residence which makes it affordable to install back up power for equipment the owner deems necessary to function..

 

[charlie b]

Re: Query: Auto Transfer Switches

I am going to put this thread on hold, for the time being.

jhc: If you wish to have this thread re-opened, please send me a Private Message. If you don't know how, look at the FAQ thread, for there is a description of the PM process there.

What I need to know is what you are "retired" from. If you were not an electrician, then we cannot help you perform electrical work at your own home. From the nature of the question, it occurs to me that this might be the case. If that is true, then you would still be welcome to use this Forum to learn whatever you want to learn. But we cannot offer advice or assistance on performing electrical installation work at your own home. Our concern is that you may get only the answer to the question that you ask, and get no answer to the thousand other questions that you should have asked, but did not know that you needed to ask. The thousand of other questions are the ones that electricians, electrical engineers, and other professionals in the electrical industry would have known about, and would have understood the answers to, as part of their years of training.

If my concerns are unfounded, then please let me know.