Multiple Line-Side Taps

[pcanning87]

I'm looking at a site that has a pretty typical existing line-side tap, with 600A tapped on the line-side of a 3000A hot-sequenced switchgear/meter. I'm potentially trying to add up to 1600A of PV as a Phase 2 addition.

1) Assuming there is room in the gear, my Plan A would be to install a second line-side tap. I don't believe there's a any Code issue with this?

2) If there is no room in the existing switchgear, I don't believe I can add a tap-box in front of the switchgear because the existing 600A tap would become a tap of a tap, which is a violation?

3a) I'm thinking I can add a new main switchgear in front of the existing gear. Say a 5000A bus with a 3000A main, a 3000A branch feeding the existing switchgear and a 1600A branch feeding the new PV system. I'm not sure if this would strictly meet 705.12(D)(2)(3)(b)&(d).

Do you guys see Code issues with either the new main or tap box methods? I'm also seeing the possibility for utility restrictions on service size, configuration, and metering locations.

Thanks.

 

[Smart $]

1) Given the simplicity of your description, I can't say there is any Code issue with this option either.

2) As long as 3000A service conductors continue through to switchgear, there is no tap of a tap. Besides, there is no rule which says you can't tap a tap on the line side of the service disconnecting means. The 'can't tap a tap rule' only applies to feeders and branch circuits.

3) If you add new main switchgear in front of existing and tie in after this new gear, it is not a line side connection... so load-side connection rules would apply.

 

[jaggedben]

(3) could potentially be problematic on two issues. One is that it would have to be possible to use the existing switchgear as load side equipment, i.e. separate EGC and grounded conductor. 2 is that your existing tap would fall under 705.12(D)(1&2) and I'm not sure that works. It does seem that you could qualify it under 705.12 (D)(2)(c), I don't see issues with b and d unless you are leaving something out, and note that you only have meet one of (a) through (d).

I'd tend to think that reusing the existing tap location is your best option, assuming you could use the existing tap hardware or get other suitable hardware. Someone already did the hard work of getting an AHJ to approve a tap on this gear, you'd be going to the AHJ and saying I want to redo the same method with bigger/more lugs. Then split the conductors again to both sources. Or do a second tap like you said.