NEC 408.36(D) Main Breaker Holddown Requirements

[wb9vxy]

Here is what Eaton says on their website:
According to NEC 408.36(D) Plug-in-type overcurrent protection devices or
plug-in type main lug assemblies that are back-fed and used to terminate
field-installed ungrounded supply conductors shall be secured in place by
an additional fastener that requires other than a pull to release the device
from the mounting means on the panel. "Field-installed" is the key, if we as
the manufacturer use a back-fed breaker or main lug assembly in a panel a
hold-down kit is not necessary. If a customer back-feeds a plug-in breaker
or main lug assembly that they field install a hold-down kit is required.

So: If I do a lineside tap do I have to add a holddown?

If I replace the breaker in kind after a failure do I have to add a holddown?

If it change the breaker size (presently 100A breaker on a 125A solar ready panel
Will use the Enphase Transfer switch to integrate the battery and PV into the system to no
PV or Batt to the MSP. ) to 125A and do the line side tap to insert the Transfer switch
between the meter and the main do I have to add the holddown?

Seems to confusing to me.

Tnx

T3

 

[jaggedben]

First, why are you talking about upsizing a main breaker? Does the customer have increased load? You can't just do this without checking the service conductors to see if they are rated 125A.

As far as your question, the hold down is required if the conductors, not the breaker, are field installed. So it depends on the panel configuration, which you haven't described.

For example, if it's a meter main combo then the wires or busbars in between the meter socket and the main breaker are factory supplied. No hold down is necessary if the factory didn't supply one. If the factory did supply a hold down, put it back. In other words, after you change the breaker re-install everything else the way the factory did it.

If it's a separate meter socket and panel, then the conductors between them are field installed, so if you are landing the conductors on the terminals of a plug-on breaker then the hold-down is required.

You've stated some phrases which to me are contradictory. 'Solar Ready' to me means a meter main, because I've only seen meter/mains sold with that phrase. But generally you can't do 'line side tap' on meter/mains. And if you were doing a line side tap there'd be no need to change the existing main breaker. So I'm pretty unclear what you are doing.

 

[jap]

I've yet to purchase a factory assembled panel with a Main Breaker or Main Lug assembly that was not somehow fixed to the bussbars.

What Manufacturer does not do that?

JAP>

 

[jaggedben]

Lots of smaller side-by-side meter mains don't have a hold down, especially the 100 and 125A. Don't ask me why, but it's so.

 

[wb9vxy]

As part of the job I replaced an old Zinsco main panel that was equipped with a 125A main. Utility said I could replace the
panel with new if I kept the main the same size (due to gas meter clearance issues)

The new Eaton meter-main panel came with a 100A main breaker and a "solar ready" 125A rated bus.

My new installation is line side tap so we removed the wires between the meter and the main.
Meter goes to 125A breaker in the Enphase Enpower transfer switch mounted next to the new panel.
I believe this new breaker is now considered the Service Disconnect.
The battery, PV, and generator all connect in to appropriate ports on the transfer switch.
Switch is rated by Enphase for 200A in, 200A out, 80A PV, 80A Battery, 60A generator.

The output lugs of the transfer switch go to a new 125A main breaker in the new panel
There are only house loads on the this main panel, no PV or battery.

No one flagged the need for a breaker holddown when we did the installation over two years ago.

We recently submitted another, similar, job and the notes came back requiring a holddown on the main.

I am a little confused as to why Eaton's wiring doesn't require holddown but mine does. Not sure why field vs
factory makes a difference. In any event, we are adding holddowns when we do line side taps.

So, I am tracking down a holddown and will take an outage and install when it arrives.

 

[wb9vxy]

A little further information. The electrician the led the job picked this particular meter-main because it had
wires, not bus bars from the meter output to the input of the main breaker. He said he had used the panel before
when adding transfer switches and generators.

 

[jaggedben]

Whether Eaton used wires or not I think you're on thin ice modifying a meter/main like that. If it doesn't have a provision for a hold down on the new 125A breaker then even more so, unfortunately.

When you installed the meter/main two years ago as it came from the factory you had no obligation to install a hold down. When you field installed new conductors now you do. Eaton is correct about this.

 

[jaggedben]

Another problem is that meter main probably has a neutral busbar bonded to the case. But as I understand your description, you turned the panel part of it into a subpanel when you inserted the Enphase switch in between the meter and the panel part, making the Enphase switch the new service panel. So now you presumably have an illegal neutral to ground bond in an enclosure contain a sunpanel. That's why the meter main almost certainly has a label that says 'suitable only for use as service equipment.'

You should have installed a physically separate meter socket and main panel instead of a meter/main combo.