Grounding Everything, Circuit for Specific Equipment

[solace396]

I'm gonna try to organize this best I can.

The equipment being supplied is a coffee bean roaster:

208/3∅
FLA ~8A
LARGEST MOTOR 2.3 HP @ 6.9 FLA

We have 120/240 Source feeding a Rotary Phase Converter:

MAX kVA 10
VOLTS 240
TYPE 2P
FLA 1∅ 48
LARGEST MOTOR 5HP

Which then is fed through a 6 kVA 240/208 Delta to Wye XFMR.

There is an abandoned water pipe in the basement being used as a grounding electrode for the service.

For the GEC from XFMR, since my ungrounded conductors are less than #2 I sized it as #8.

EGC load side just matching ungrounded.

Now what has got me confused is my EGC coming from panel to phase converter #10 based on #6 hot line side. But my supply side bonding jumper for the XFMR is to be a minimum of #8.

I'm using a magnetic contactor as disconnect for phase converter in 12x12 box, to an 8x8 box that supplies phase converter and manufactured leg control panel and fusible disconnect for XFMR.

My main question right now is, do I run EGC and SSBJ in tandem? Do I have to bond my SSBJ to every enclosure on the way to the XFMR like I'm doing with EGC? Or can I just weave it through the circuit directly to my XFMR?

 

[ptonsparky]

Your supply to the transformer uses an EG. Size it according to the fusing/cb ahead of it. It goes to the frame only.

 

[ptonsparky]

Your supply to the transformer uses an EG. Size it according to the fusing/cb ahead of it. It goes to the frame only.

NM. ignore this.

 

[solace396]

NM. ignore this.

It's what New Mexico doesn't require that I guess I need to look and see what their local code is.

Another question I have that abandoned water pipe comes up like 6 ft and dogs off after a 90. Can I cut that down to where it's just sticking up a foot out of the concrete?

 

[LarryFine]

I thing NM meant never mind, not New Mexico.

 

[ptonsparky]

NM = Never mind in this case, I didn't notice your location. oops.

Your #10 EG goes all the way thru to the case of the Xfmr. Bonding as needed.
The SSBJ is either at the transformer or at the secondary disconnect. Your choice.
250.30(2)

 

[Dsg319]

NM = Never mind in this case, I didn't notice your location. oops.

Your #10 EG goes all the way thru to the case of the Xfmr. Bonding as needed.
The SSBJ is either at the transformer or at the secondary disconnect. Your choice.
250.30(2)

SSBJ goes from your transformer to your first OCPD and is based on size on ungrounded conductors. From there on there is just an EGC based off of branch circuit breaker sizes.

I think what ptonsparky meant was your MBJ can be at either place. Transformer or disco.

 

[solace396]

SSBJ goes from your transformer to your first OCPD and is based on size on ungrounded conductors. From there on there is just an EGC based off of branch circuit breaker sizes.

I think what ptonsparky meant was your MBJ can be at either place. Transformer or disco.

Okay so in this situation are y'all saying I need secondary protection on the transformer? Because I currently have not configured in that secondary disconnect?

 

[ptonsparky]

SSBJ goes from your transformer to your first OCPD and is based on size on ungrounded conductors. From there on there is just an EGC based off of branch circuit breaker sizes.

I think what ptonsparky meant was your MBJ can be at either place. Transformer or disco.

Yes, thank you.

 

[ptonsparky]

Okay so in this situation are y'all saying I need secondary protection on the transformer? Because I currently have not configured in that secondary disconnect?

Yes.

ETA: see table 450.3(B) and 240.21

 

[solace396]

But I do understand what you're saying about the mbj and ssbj, would my EGC on the line side then count as my ssbj for the transformer and need to be sized up basically to the transformer rather than as an EGC for the line side of the phase converter?

 

[ptonsparky]

The primary side of the transformer has an EG sized to the protection ahead of it.
Once you hit a transformer you start over.

 

[solace396]

The primary side of the transformer has an EG sized to the protection ahead of it.
Once you hit a transformer you start over.

Okay just in this situation the line of my phase converter is sized #6 w/ #10 EG, the secondary of phase converter/primary transformer is sized #12 but code requires #8 minimum SSBJ.

Please clarify in this instance if the ssbj and egc on line side of transformer are the same conductor and needs to be sized accordingly.

And thank you for all your help greatly appreciate it and really helps.

 

[jaggedben]

Is the output of the rotary phase converter a separately derived system? I'm guessing yes.

 

[solace396]

Is the output of the rotary phase converter a separately derived system?

It's hard to say, it uses basically an induction generator and capacitors to manufacture the third leg, so technically that leg is separately derived.

 

[ptonsparky]

The RPC is not a separately derived system.
A SDS starts after the transformer.