Type of OCPD & disconnect for line side tap

Status
Not open for further replies.

ggunn

PE (Electrical), NABCEP certified
Location
Austin, TX, USA
Occupation
Electrical Engineer - Photovoltaic Systems
So basically their rule is 'do it like the drawing because we are not smart enough to read the code and determine with our own minds if it meets code.' I'm glad I'm not dealing with that. :slaphead:

So what do you do when you have a meter main combo with slots for multiple service disconnecting breakers? Or do those not exist in your area?

It's not that bad. I have had some success arguing points of code when my designs did not conform exactly with their drawings, just not on the point of a bladed disco vs. a breaker for a PV system disconnecting means. I have not yet encountered a meter main combo around here, but I have encountered MLO panels fed directly from a meter with no OCPD. San Antonio says we cannot land a PV breaker in a MLO MDP, period. We either have to install a main breaker in the MDP or make a line side connection in a separate tap box.

Austin won't allow it either, but they will allow a bladed fused disco to feed a MLO MDP busbar, and if there are 6 breakers there already, they do not count the PV disco as a seventh handle. I have not tried to fly that design in San Antonio, but since they consider the PV interconnection in a line side connection to be a service disconnect (Austin doesn't), I'd bet they won't allow it.
 

jaggedben

Senior Member
Location
Northern California
Occupation
Solar and Energy Storage Installer
...San Antonio says we cannot land a PV breaker in a MLO MDP, period. We either have to install a main breaker in the MDP or make a line side connection in a separate tap box....

That's what would tick me off. A completely illogical and unsupportable (by code) policy, which turns what should be the easiest type of interconnection into a huge hassle and additional expense. Requiring a bladed lockable disconnect somewhere does not raise my hackles as compared to requiring modification or replacment of existing equipment that's already ideally set up for interconnection.

I guess if you don't have meter/main combos it may not seem quite as unjust.

As for sixth vs. seventh handles, I think it depends if you're adding a new set of service conductors or not. But at least there are parts of Article 230 that can be referenced on that matter.
 

ggunn

PE (Electrical), NABCEP certified
Location
Austin, TX, USA
Occupation
Electrical Engineer - Photovoltaic Systems
That's what would tick me off. A completely illogical and unsupportable (by code) policy, which turns what should be the easiest type of interconnection into a huge hassle and additional expense. Requiring a bladed lockable disconnect somewhere does not raise my hackles as compared to requiring modification or replacment of existing equipment that's already ideally set up for interconnection.

I guess if you don't have meter/main combos it may not seem quite as unjust.

As for sixth vs. seventh handles, I think it depends if you're adding a new set of service conductors or not. But at least there are parts of Article 230 that can be referenced on that matter.

I pick my battles and I try not to tilt at windmills. The rules are what they are and I deal with them. We build so many systems that it is often counterproductive to fight over fine points in the NEC, even if it means we have to work a little harder to get a system to pass inspection. Some places we have to do things that make a system cost more to the customer, but as long as the rules are applied with equanimity it doesn't put us at a competitive disadvantage.
 

GoldDigger

Moderator
Staff member
Location
Placerville, CA, USA
Occupation
Retired PV System Designer
I think that most AHJs can apply the rules with equanimity. Some will apply them with rancor, some with diffidence.
But they should all apply the rules equitably too.
 

jaggedben

Senior Member
Location
Northern California
Occupation
Solar and Energy Storage Installer
I pick my battles and I try not to tilt at windmills. The rules are what they are and I deal with them. We build so many systems that it is often counterproductive to fight over fine points in the NEC, even if it means we have to work a little harder to get a system to pass inspection. Some places we have to do things that make a system cost more to the customer, but as long as the rules are applied with equanimity it doesn't put us at a competitive disadvantage.

If I couldn't do supply-side connections with breakers then in each of the last several months I'd have probably had to tell a dozen or so customers that we needed a change order for a service panel replacement, costing them between two to four grand on top of the original solar contract. (Most of these contracts cost between 10 and 30 grand, so not a rounding error.) That's how common MLO meter/mains are around here. I'd much rather argue with AHJs for a bit than give all that bad news to my customers. If I did have an AHJ pulling that nonsense, I'd recommend to the customers to complain to their elected officials. :happyyes: That's a lot of money for a shirt pocket rule.
 

ggunn

PE (Electrical), NABCEP certified
Location
Austin, TX, USA
Occupation
Electrical Engineer - Photovoltaic Systems
I'd much rather argue with AHJs for a bit than give all that bad news to my customers.
Oh, I argued with them, all right, but it got me nowhere.

In San Antonio there are many, many residences with MLO MDP's (even new construction) and for every one of them we have to either upgrade the service with at least adding a main breaker, or we have to install a tap box (and break the ground, drive an auxiliary ground, tie the G to N in the tap box, etc.) between the meter and the MDP. We get plenty of work there, anyway.
 
Status
Not open for further replies.
Top