Metermain & Line-Side Tap

[shortcircuit2]

The job has an existing 200amp underground metermain that is bused so no line side tap can be added ahead of the 200amp main for a 70amp solar backfeed.

Do any of the manufacturers make an all in one 200amp metermain with provisions for lineside taps?

 

[SolarPro]

I'd check out Milbank. They offer a load tap connector for their 200 A meter sockets:

[Kansas City, MO] PV installations utilizing a line-side utility interconnection now have an option for making that connection directly inside the meter enclosure. Milbank, manufacturer of a wide variety of electrical products including meter sockets, has introduced a meter base load-side connector for use in its 200 A meter sockets. The assembly (manufacturer part number K4977-INT) replaces the load-side nut assembly with a UL-listed double-lug assembly. This allows for a connection of up to 100 A on the load side of the meter socket in addition to the existing 200 A service feeders. The load-side connector eliminates the need for splicing conductors or setting additional enclosures and avoids Code violations associated with altering listed equipment.
Milbank Manufacturing / 877.483.5314 / milbankmfg.com

And they make meter mains:

http://www.milbankmfg.com/Products/MeterMainBreaker/index.asp

 

[shortcircuit2]

There is no way to tap ahead of the main breaker in the metermain because it is bused from the meter load side to the line side of the main breaker in the existing piece of equipment.

We are considering adding a 200amp main at the inside panel and tapping ahead of that breaker with the 70amp solar backfeed.

 

[SolarPro]

Gotcha. I thought maybe you were looking to replace the existing equipment.

If the inside panel is located on the load side of the main breaker, aren't you are subject to the 120% rule regardless? How do you make a supply-side connection on the load-side of a main breaker?

 

[shortcircuit2]

Thanks for the feedback Solarpro. Yes we were thinking of replacing the metermain...but it has the main on the left and meter on the right, and most new equipment I have searched has the meter on the left and main on the right...so changing the meter main is difficult.

So we are considering the breaker in the subpanel as I layed out before...but as you have pointed out it is subject to the 120% rule still. There would only be a problem if someone tapped the feeder later on. I will run it by the AHJ and hope he will allow it.

 

[SolarPro]

Sure. I see what you're proposing.

It never hurts to ask. You might also propose adding a warning label so that no one adds a tap later. You're right. That's the only way anything is ever overloaded.

Let us know if it works.

 

[c_picard]

The conductors in your scenario would be subject to the 120% rule also.

Replace the meter main with a 4 space meter main, and backfeed there?
Seems like less work than replacing the loadcenter.

 

[So Cal]

Siemens makes a "solar ready" 200A all in one OH or UG. It has a line side tap breaker spot built in, but it has the meter on the left and main breaker on the right, plus, I just looked it up and it's set up for max 60A solar breaker.

If the existing load calcs allow, you can replace the 200A main breaker with 150, then the 120% works out. I don't know your situation, but on a residence that has gas heating and gas water heating this almost always works.

 

[shortcircuit2]

It was such a difficult setup with the existing meter-main that a decision was made to replace the main 200amp load center with a new Square-D 200amp 42 circuit panel with 225amp bussing. Now the 70amp solar backfeed breaker works with the 120% rule 705.12(D)(2) with regard to the panel bus.

The conductors between the meter-main and the panel are near impossible to tap due to the fact they they go under a slab in conduit and right into the back of the panel in the basement.

The AHJ is comfortable with the arrangement and the property owner is happy to get a new panel.