Bonding of fused disconnect?

[hitehm]

Please see the attached image. I'm trying to remember why the fused disco needs to have N+G bonded and a bare #6 GEC run from the fused disco to the main N/G terminal in the MSP. I assume this is all GEC system related and not EGC related since any ground fault in the disco enclosure would clear through the EGC like any other grounded enclosure. Firstly, doesn't bonding the N+G in the fused disco create 2 current paths for the unbalanced N current during normal operation, 1 through N and the other through the bare #6 from the disco to the MSP ground terminal? Also notice the MSA (meter socket adapter) for the solar interconnection has its own 40A solar breaker, so does the fused disco even need to be fused? Sorry, my CRS is bad on this and I'm not even sure I ever knew it to forget it!

 

[jaggedben]

The ConnectDer meter socket adapter only brings a neutral to the fused disconnect. Therefore to establish your EGC beyond the fuser disconnect you need to have a main bonding jumper. A ground fault would not clear through the EGC without the main bonding jumper.

The 40A breaker in the MSA is kind of weird; I think it's not intended to be treated as a service disconnecting means, it's more of a meter disconnect or something. It's hard to treat it as service disconnect when it's not in its own proper enclosure.

Recent related topic here:

PV Disconnect Grounding

I have a PV roof mount system using a supply side connection at the meter, Milbank. The conduit to the PV disconnect is not calling for a separate ground. The plans essentially call for the neutral to be the neutral and ground. I can not find a code to support this but engineer claims this is...

forums.mikeholt.com

 

[hitehm]

The ConnectDer meter socket adapter only brings a neutral to the fused disconnect. Therefore to establish your EGC beyond the fuser disconnect you need to have a main bonding jumper. A ground fault would not clear through the EGC without the main bonding jumper.

The 40A breaker in the MSA is kind of weird; I think it's not intended to be treated as a service disconnecting means, it's more of a meter disconnect or something. It's hard to treat it as service disconnect when it's not in its own proper enclosure.

Recent related topic here:

PV Disconnect Grounding

I have a PV roof mount system using a supply side connection at the meter, Milbank. The conduit to the PV disconnect is not calling for a separate ground. The plans essentially call for the neutral to be the neutral and ground. I can not find a code to support this but engineer claims this is...

forums.mikeholt.com

So isn't this establishing 2 normal N current paths, one through the N going to the meter socket and the other through the bare #6 GEC going to the N/G main bonding jumper terminal in the msp?

 

[wwhitney]

So isn't this establishing 2 normal N current paths, one through the N going to the meter socket and the other through the bare #6 GEC going to the N/G main bonding jumper terminal in the msp?

Yes, that always happens with more than one service disconnect on a single service. It's an unfortunate side effect of the required connections. Nothing you can do about it.

Cheers, Wayne

 

[hitehm]

Yes, that always happens with more than one service disconnect on a single service. It's an unfortunate side effect of the required connections. Nothing you can do about it.

Cheers, Wayne

I'm looking at the installation manual for the ConnectDER MSA and it clearly shows wiring for the EGC up to the meter adapter, which has an integral G to N bonding jumper (see pic clearly showing the green egc from the non-fused disco). It also has a factory installed solar breaker. So wired as instructed by the manufacturer, I don't understand why a N/G bond is needed in the fused disconnect and even more so, why a fused disconnect at all if the collar has the required OC protection? Th collar essentially works like the Siemens "Solar-Ready" panels that have a dedicated line-side slot for the solar breaker. The wiring in the diagram seems to be ignoring all the simplified built-in functions of the collar. Is there a code requirement I'm missing here?

 

[wwhitney]

I'm looking at the installation manual for the ConnectDER MSA and it clearly shows wiring for the EGC up to the meter adapter, which has an integral G to N bonding jumper (see pic clearly showing the green egc from the non-fused disco). It also has a factory installed solar breaker.

Are you sure it has an integral G-N jumper? Is the breaker in it user accessible?

If it has an integral G-N jumper, then I would be inclined to say that you shouldn't have another G-N jumper downstream. What does the manual say?

Cheers, Wayne

 

[jaggedben]

Ok, looking again, I take it back. The manual (latest version) seems to treat the N terminals in the MSA as a main bonding jumper. (The line side diagram on pg 8 confused me. See pgs 42 and 47 instead.) I also think you could probably do it either way. That is, treat the breaker in the MSA as a service disconnect and bring an EGC from the MSA, and not bond in the fused disconnect. (Note, then you don't actually need the disconnect, or at least don't need it to be fused). Or, treat the MSA breaker as a meter disconnect and treat the fused disconnect as the service disconnect, like I said before. The drawing in the OP is the second option. But it does not agree with pgs 42 and 47 of the manual.

To go back to discussions we used to have before the code made things a bit clearer, to be safe..
Either bring both a neutral and an EGC from the MSA, and don't bond later.
OR
Bring only a neutral, and do bond to ground in the disconnect.