Meter socket transfer switch NEC OK?

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  #1  
Old 06-12-15, 06:52 AM
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Meter socket transfer switch NEC OK?

This seems like a simple and inexpensive way to safely add a transfer switch for temporary generator power. So I'm wondering why I've only seen similar products online and never in a store or catalog. Are they not allowed anywhere?

For the old manual one pictured an electrician unclamps the meter and plugs this switch in between. Then wire an inlet box to the knock-out.
There are newer automatic switches I found with Google but they really don't appear to offer any advantage when used with a manual-start generator.

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Old 06-12-15, 07:19 AM
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I see you are in MI. If you are in a Consumers Power area, they offer a couple generator compatible meter sockets like that one.

https://www.consumersenergy.com/content.aspx?id=1225

You can also install a variety of auto or manual transfer switches after the meter if you use the standard meter socket.

The NEC sort of doesn't matter when it comes to meter sockets, because each power company has a distribution standard which trumps the NEC. They also usually have approved lists, and in many cases (such as Consumers) the power company usually owns the socket.
 
  #3  
Old 06-15-15, 06:32 AM
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Why are the meter socket/transfer switch units shown in the link always so huge? They're giant panels full of dead air. My service is underground and comes up to a standard small meter socket via 3" rigid. Right under the socket, next to the rigid, is a tight "S" bend in the SER cable directly through the wall and into the top of the distribution panel. If I were to mount one of those commercial-looking boxes on my existing conduit the meter-reader might need a ladder to read the meter!
 
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Old 06-15-15, 07:22 AM
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The size of the box is usually based on the minimum safe bending radius of the maximum allowed conductor size for the lugs included. There is also minimum required clearance between hots, neutrals and the grounded cabinet for the operation of the switchgear itself and for the meter jaws. The box needs to be able to contain a full amperage arc for the size of the service which is much, much more powerful than you think it would be.

The box should be set so that the center of the meter socket is as close to 5' from the finished grade as practical, although in some cases they do allow taller. You may have option of exiting the back of the cabinet to enter the house or mounting it to the side and using an LB or a big "U" shape of conduit and an LB fitting to enter the house at the right location. There might be other ways to reroute the service entrance to accommodate the switch gear.
 
  #5  
Old 06-15-15, 08:54 AM
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Thanks Ben. I think this one is a non-starter if Consumers will only allow those enormous enclosures. I'll have to try to find space for a new length of SER cable to reach to a transfer switch indoors.

The device I pictured appears to be a nice piece of engineering and "efficient" if nothing else.
 
  #6  
Old 06-15-15, 09:15 AM
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There are often a lot of options you might not be thinking of that a contractor might come up with looking at the site. We might be able to make some suggestions if you post photos of the area. Getting a bid or two wouldn't be a bad idea either. The switchgear can usually be located in a basement or garage. Only the meter is required to be on the exterior of the house. Depending on the configuration a disconnect switch might also be required in some cases. Moving the meter is sometimes an option, but that gets expensive with underground service. I'll see if I can find my link to the full service standard that lists all of the possible configurations and approved meter sockets.
 
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