PFC cap banks and correct wiring practices?

[herding_cats]

I just started contracting for a new company that does a lot of power factor correction cap banks with harmonic filters, etc. They sent me the data sheets from the manufacturers and install guidelines. What I saw was a major red flag:

Most of these cap banks were installed using the main service lugs either at main breaker or main disconnect because the MDPs were already filled with breakers. In some of these installs, there were connecting #6 wire to the main lugs, like on 400A service, then feeding them out to a disconnect, then to the cap bank. I know of nothing about the connections of cap banks in NEC guidelines, but I sure as hell know about ampacity and branch circuits. I talked to one of the electricians that works for the company that produces these cap banks, and he basically said “we have to do what we need to get them installed” and “cap banks are not considered a load”.

If there is room at the MDP then they do connect to a breaker. If not, they jump on the main lugs or even install “flag” terminals on the main lugs.

If anyone knows about this please respond.

See the cap bank manufacturer rep here:

www.C3Greenenergy.com

 

[texie]

OMG. You are working for another of many vendors selling snake oil. Your post indicates you are installing cap banks and they have their place in certain situations. But that is not what I'm seeing on their website. Regardless, you are correct about questioning how they are connected. Even if they are listed for connection on the line side (doubtful) you will not encounter lugs in the field that would allow just placing a different size conductor in the same lug of a service.
While I did not dig deep on their website I would be curious of what exactly standard these products are to listed by an NRTL. Do you know if they have any ligament NRTL listing?

 

[herding_cats]

Look. I am an expert in mechanical engineering and have a deep understanding of PFC. There are many applications where PFC is important or even critical. My application is working on a 460v/12vdc charging rectifier with a PF of .28. What I am asking here is not advice on PFC cap banks, but more so for NEC code on main lug connections. I do not buy snake oil, and I can identify it clearly.

I will find out about NRTL listing. But it doesn't have anything to do with best wiring practices, or main lug connections.

 

[don_resqcapt19]

Assuming by "main" you mean service disconnect(s), the capacitor disconnect will become a service disconnect. This can be legal as long as there are no more than six service disconnects, including the PFC disconnect, the connection for the PFC conductors is made in a code compliant way on the line side of the service disconnect(s) and the PFC disconnect has overcurrent protection that does not exceed the ampacity of the conductors that supply the PFC disconnect.

 

[herding_cats]

Thats the real issue here the ampacity of conductors. But are cap banks considered a load?

There are all kinds of connection points these guys have been making to install these:

adding lugs to existing mains to run smaller service wire to disconnects, then to cap banks

Using "flag" terminals added to service mains, service disconnects,

modifying main lugs so they can accept another set of wires, usually smaller ampacity conductors (major red flag on this)

 

[ptonsparky]

They pass current. The customer just isn't billed for it. Protect them however the mfg suggests. Tap rules could come into play and allow for some distance with smaller conductors. How that is done is the problem.

 

[herding_cats]

Thanks ptonsparky. section 240.?? on tap rules I believe. OUTSIDE the building on MD of service.

 

[ptonsparky]

240.21(b)(5) Outside Taps for Feeders
The taps would need to be on the load side of the Service Equipment.

 

[kwired]

Don mostly covered the tap to the service side - there is no tap rule there. The taps are service conductors and you are creating a service with multiple service disconnecting means. Can be perfectly code compliant if you terminate properly and comply with anything else that may come up in art 230 like a disconnected rated suitable for use as service equipment, grouping requirements, number of disconnects allowed, etc.

Obviously can not slip the 6 AWG in same lug port as the original service conductor is in as mentioned in OP.