How to connect MCCB to control transformer?

[LMAO]

I have a molded case circuit breaker feeding a VFD and control power transformer in my VFD cabinet. VFDs and breakers are different sizes, anywhere from 60A to 500A at 480V. My question is: what is the best way to tap off load side of breaker to control power transformer? For example, in my 100HP VFD cables are 2/O which are terminated in 200A breaker, so far so good. But I also need to connect 2 control power transformer cables which are 14AWG in load side of the breaker to feed a single phase 480:120V control transformer. We are currently using a certain brand of breaker which comes with quick disconnects (see picture) that I can terminate my female disconnects. But I am considering using a different type of breaker that does not have the option of quick disconnects for smaller wires. In this case, what is the best way to connect the small 14AWG wires to breaker? it is a UL508 enclosure.
thanks

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[petersonra]

Many breakers these days have what are called distribution lugs that you can get that have multiple holes just for this problem. Depending on the wire size it is not a perfect solution.

Some manufacturers have lugs that have tapped holes in them for this purpose as well.

The most common non-code solution is to either jam the #14 into the lug with the big wire or drill and tap the lug yourself.

I have been known to add a ring lug for control wires under the bolts that hold the CB lug in place. This does not always work depending on the lug and bolt configuration.

Panduit makes a compression splice that can be used to connect a #12 and a 3/0. Just strip the big wire back a little, splic in the #12 and then insulate it and stick the big wire into the CB lug.

A Polaris tap will work too.

However, I have generally been able to avoid having to use some kind of splice by selecting the right CB.

 

[Jraef]

LEGALLY, per UL-508, you must use a breaker lug that has a LISTED Control Power Tap (like what you showed), or tap off of the device that the CB is feeding, in your case the VFD, IF those lugs are listed for the purpose, or use a Power Terminal Block (PTB). The tricky part about the PTB is making sure it doesn't mess you up on the SCCR. Many of them, Polaris for example, do NOT have an SCCR, which means you will be limited to 10kA as the "courtesy" listing of an untested PTB.

Now, if you are putting together your own VFD control panel with components that have not been listed together (as evidenced by you thinking of changing breakers), you are likely limiting yourself and your customers to a 5kA SCCR anyway, so that Polaris block issue would be moot.

 

[LMAO]

Many breakers these days have what are called distribution lugs that you can get that have multiple holes just for this problem. Depending on the wire size it is not a perfect solution.

Some manufacturers have lugs that have tapped holes in them for this purpose as well.

The most common non-code solution is to either jam the #14 into the lug with the big wire or drill and tap the lug yourself.

I have been known to add a ring lug for control wires under the bolts that hold the CB lug in place. This does not always work depending on the lug and bolt configuration.

Panduit makes a compression splice that can be used to connect a #12 and a 3/0. Just strip the big wire back a little, splic in the #12 and then insulate it and stick the big wire into the CB lug.

A Polaris tap will work too.

However, I have generally been able to avoid having to use some kind of splice by selecting the right CB.

LEGALLY, per UL-508, you must use a breaker lug that has a LISTED Control Power Tap (like what you showed), or tap off of the device that the CB is feeding, in your case the VFD, IF those lugs are listed for the purpose, or use a Power Terminal Block (PTB). The tricky part about the PTB is making sure it doesn't mess you up on the SCCR. Many of them, Polaris for example, do NOT have an SCCR, which means you will be limited to 10kA as the "courtesy" listing of an untested PTB.

Now, if you are putting together your own VFD control panel with components that have not been listed together (as evidenced by you thinking of changing breakers), you are likely limiting yourself and your customers to a 5kA SCCR anyway, so that Polaris block issue would be moot.

This pretty much means I cannot use the breaker without the transformer connectors.
Thanks.

 

[don_resqcapt19]

Does the breaker manufacturer have a field modification kit that would let you add terminals suitable for the purpose?

 

[petersonra]

Now, if you are putting together your own VFD control panel with components that have not been listed together (as evidenced by you thinking of changing breakers), you are likely limiting yourself and your customers to a 5kA SCCR anyway, so that Polaris block issue would be moot.

IIRC, polaris blocks are listed as connectors so don't require a SCCR. They are like crimp on lugs in that respect.

 

[Jraef]

IIRC, polaris blocks are listed as connectors so don't require a SCCR. They are like crimp on lugs in that respect.

No, NSi specifically says they are 10kA SCCR, which is the untested "courtesy" listing for PTBs (different than the 5kA for other power circuit devices though). There are some PTBs out there that have higher SCCR ratings though. Some are rated at up to 65kA without fuses ahead of them, you just have to look around a bit to find them. For a while, component mfrs were not paying attention to that issue, but a lot of panel builders got twisted up by that and demanded it, so a few suppliers have responded.