Wiring Question - Pro/Tran2 Transfer Switch

[Steelart99]

I'm installing a Pro/Tran2 Transfer Switch (10 circuit) with my 6000xp Inverter. When I attached all the wires from the Transfer Switch into the Main Panel, there was also a ground wire and Neutral wire that got connected. The ground wire from the main panel is attached to the casing of the transfer switch, but the neutral just hangs out loose within the transfer switch casing (see pic below).

My main breaker panel does not have specific bus bars for ground or neutral, so both ground and neutral are mixed together on the bus bars within the main panel.

I also ran a separate ground and neutral (6 AWG) from the main breaker panel to inverter.
I will be running a set of hot wires from the inverter "Load" to the red/black wires in the transfer switch.

So, my question is: do I need to run a neutral back from the inverter to the transfer switch? It wouldn't seem so since the "neutral" and ground are already connected within the main panel and the ground is connected to the frame of the transfer switch.

 

[timselectric]

The problem is that the protran transfer panel isn't designed for this use.
It's designed to allow you to select between two sources for the individual loads.
It's not designed to have the same source form a loop between the two inputs.
Which is what you are doing when you connect the inverter input to the main panel.
The safest option is to cap the neutral in the protran and not connect it to anything. Luckily the 6kxp is using a common neutral setup. So you already have a neutral return path from the inverter to the main panel, for the loads.

 

[TM48]

I believe that neutral wire is used if you have installed any AFCI or GFCI in the Protran switch.

 

[Steelart99]

The problem is that the protran transfer panel isn't designed for this use.
It's designed to allow you to select between two sources for the individual loads.
It's not designed to have the same source form a loop between the two inputs.
Which is what you are doing when you connect the inverter input to the main panel.
The safest option is to cap the neutral in the protran and not connect it to anything. Luckily the 6kxp is using a common neutral setup. So you already have a neutral return path from the inverter to the main panel, for the loads.

I'm not sure I understand what you mean when you say "the same source form a loop between the two inputs". The Protran is designed to take generator input and the switching transfer is between the that input and grid input. I'd assumed that 6000xp source input to the Protran is identical to source input from a generator. Am I missing something?

1.) Thinking about it ... are you saying that because the 6000xp takes input from the grid, and could use that input as the output power source to the transfer switch (if solar and battery not available), that conceivably the transfer switch is essentially switching between the grid and the grid? I.e., "the same source?"

2.) So, the inverter is connected to the Protran at 240VAC. The Protran ground comes from the main panel connected to Protran casing. But, as best I could tell there was no neutral connection within the Protran from the main panel or inverter to support the 120VAC circuits. Except that the neutral/ground tie was within the main panel (about 18" away). Is the Protran using the ground as the "neutral?" This was kind of the impetus for my original question.

 

[timselectric]

that conceivably the transfer switch is essentially switching between the grid and the grid? I.e., "the same source?"

Yes
But, you should be fine as long as you don't use that neutral between the main panel and protran. This way you will avoid the loop with the N/G bond on both ends.

 

[TM48]

Is the Protran using the ground as the "neutral?

No it's not. All metallic boxes must be grounded. You only need the white neutral wire if you add AFCI or GFCI breakers in the Protran box. That's what the extra white white is for. It's in the instructions that came with the Protran. The circuits you are switching have a neutral from the original load center.

 

[timselectric]

That neutral is what you would normally connect the neutral of the auxiliary source to. But in this scenario, you should not use it.

 

[Steelart99]

Awesome input gentlemen. Thank you. I did have the proverbial "lightbulb" come on as I read your comments.

 

[Aspendell Fire Pits]

First - I am a DIYer - not a licensed electrician…

I am basically doing the same thing except my 6000 xp feeds a subpanel (unbonded N & G) first and then feeds to the Pro Tran through a 40 A breaker. Neutral and ground both run from inverter to subpanel & then from subpanel to main panel where my sole N-G bond is.

I grounded Protran housing to subpanel with the supplied green ground wire and will NOT use the supplied white neutral.

Pro Tran instructions call for four wires between generator outlet (in this case replaced by Inverter)) and Pro Tran - 2 Hots, 1 Neutral & 1 ground. The two hots from generator connect to Pro Tran Red & Black Gen inputs. The neutral and ground simply “pass through” the Protran to the main panel (other than boding the Protran housing). Since there are separate N & G from inverter (back-up power) to the main panel already, I assume they would replace the neutral and ground supplied with the Protran (other than the ground fro bonding Pro Tran housing). Does this make sense?

I do see the need for the Protran neutral to panel only if a GFCI breaker will be used in the protran (someone else mentioned this - is that correct?) One would have to wire nut every GFCI neutral to that single supplied neutral since there is not neutral bus in the Protran (seems a bit sketchy to me - e.g., what if I had all 10 GFCI for some weird reason??))

Here is my additional question - how does protran get away with quantity 20, 12 AWG + an 8 AWG neutral in a 1” FMC and use this for 20 amp circuits (all breaker positions in Pro Tran are rated for 20 amp). Should not the ampacity of the 12 AWG not be derated by 50% or more?? Side Note - Slots A & B are rated for 30 A breaker and use 10 AWG.

I’ve also seen threads of concern elsewhere about the 10 AWG wiring supplied for power input to the 50 amp Pro Tran. The responses have basically been “well, it’s UL listed & its a very short 10 AWG so it must be good.” Does that sound reasonable and does same apply for the 20 or so 12 AWG wiring on 20 amp circuits?

 

[TM48]

As far as the neutral white wire it is only a sense wire no real current flows on it and is there only for GFCI usage. The 12 AWG wire is fine for a 20 amp circuit. The ProTran only switches the hot. The original neutral wire in your main panel is still used for each circuit.

 

[Aspendell Fire Pits]

As far as the neutral white wire it is only a sense wire no real current flows on it and is there only for GFCI usage. The 12 AWG wire is fine for a 20 amp circuit. The ProTran only switches the hot. The original neutral wire in your main panel is still used for each circuit.

Are you saying the neutral is unnecessary in general (except for GFCI) OR in the specific cases listed here by me & OP where there is another (separate) neutral between the inverter & the Main Panel. You need a neutral between the back up source (GEN or Inverter) & main panel somewhere, no?

Also - 12 AWG is good for 20 amp circuit even with 20 of them jammed in 1" FMC?? What is point of doing a derating calc then? Is it not applicable here??

 

[TM48]

There should be neutral and ground wires in the pig tail to attach to the main load center.

 

[Steelart99]

As far as the neutral white wire it is only a sense wire no real current flows on it and is there only for GFCI usage. The 12 AWG wire is fine for a 20 amp circuit. The ProTran only switches the hot. The original neutral wire in your main panel is still used for each circuit.

"The original neutral wire in your main panel is still used for each circuit."
This is where my lightbulb lit up ...

 

[Aspendell Fire Pits]

Disclaimer again - not an electrician but this is how I understand things based on my DIY edumacation. Please correct me if I am completely off base here!!

Yes, but I interpret that original neutral as a completely different neutral than the one being discussed. That neutral I assume is the neutral that comes back to your main panel with each original circuit. Before install of the inverter & Xfer switch you had a hot (black) wire from each (single pole) breaker in your main panel to various loads (lights/outlets) and then a white neutral back to your main panel neutral bus. The neutral brings power back to the source and current definitely flows on that neutral wire. That bus is connected to yoru service neutral that complete the circuit with the grid. Current flows on your main neutral as well when you have an imbalance of current between your two legs. So unless you have all 240V loads or a perfectly balanced system I am pretty sure you will have a current carried on the neutral back to your power source (grid or inverter)

With the transfer panel in place, the hot wire to your loads is fed through the xfer switch EITHER from the original main panel breaker (Grid) OR from your generator/inverter (GEN). When the inverter is the source you need a neutral back to the source from the main panel to complete the circuit —> Xfer SW Hot/load/original circuit neutral/main panel neutral bus/NEW neutral from main panel to back up source (GEN/INV). The white wire in the Pro Trans harness goes from the main panel neutral bus back to the panel & the main question in this thread (I think?) is what does it get connected to??!! I say it gets connected to the neutral of your back up power source (inverter or gen). Your gen cord would have 4 wires - 2 hot, 1 N and a GND. The Gen cord netral connects to the Protran White (per Protrans instructions) & that completes the circuit back to Gen. In your (our) case, it is connected to the inverter neutral.

However, based on your original post you have a separate neutral (and GND) running directly from your inverter back to your main panel. This negates the need to route that neutral through the Pro trans and back to main panel using the supplied white wire. The Protrans neutral is replaced with the one you ran separately from inverter to main panel. As such, it could be tossed (in the absence of any GFCI circuits in your Xfer switch breaker array?)

Yes/No/Maybe??????

 

[timselectric]

Disclaimer again - not an electrician but this is how I understand things based on my DIY edumacation. Please correct me if I am completely off base here!!

Yes, but I interpret that original neutral as a completely different neutral than the one being discussed. That neutral I assume is the neutral that comes back to your main panel with each original circuit. Before install of the inverter & Xfer switch you had a hot (black) wire from each (single pole) breaker in your main panel to various loads (lights/outlets) and then a white neutral back to your main panel neutral bus. The neutral brings power back to the source and current definitely flows on that neutral wire. That bus is connected to yoru service neutral that complete the circuit with the grid. Current flows on your main neutral as well when you have an imbalance of current between your two legs. So unless you have all 240V loads or a perfectly balanced system I am pretty sure you will have a current carried on the neutral back to your power source (grid or inverter)

With the transfer panel in place, the hot wire to your loads is fed through the xfer switch EITHER from the original main panel breaker (Grid) OR from your generator/inverter (GEN). When the inverter is the source you need a neutral back to the source from the main panel to complete the circuit —> Xfer SW Hot/load/original circuit neutral/main panel neutral bus/NEW neutral from main panel to back up source (GEN/INV). The white wire in the Pro Trans harness goes from the main panel neutral bus back to the panel & the main question in this thread (I think?) is what does it get connected to??!! I say it gets connected to the neutral of your back up power source (inverter or gen). Your gen cord would have 4 wires - 2 hot, 1 N and a GND. The Gen cord netral connects to the Protran White (per Protrans instructions) & that completes the circuit back to Gen. In your (our) case, it is connected to the inverter neutral.

However, based on your original post you have a separate neutral (and GND) running directly from your inverter back to your main panel. This negates the need to route that neutral through the Pro trans and back to main panel using the supplied white wire. The Protrans neutral is replaced with the one you ran separately from inverter to main panel. As such, it could be tossed (in the absence of any GFCI circuits in your Xfer switch breaker array?)

Yes/No/Maybe??????

Yup
You've got it.

 

[Aspendell Fire Pits]

Thanks Tim! Any chance you could address the question on derating of the 20 12 AWG wires in 1” FMC (pasted below)

Much appreciated!

Here is my additional question - how does protran “get away with” quantity 20, 12 AWG + an 8 AWG neutral in a 1” FMC and use this for 20 amp circuits (all breaker positions in Pro Tran are rated for 20 amp). Should not the ampacity of the 12 AWG not be derated by 50% or more or am I not understanding how derating works?? Side Note - Slots A & B are rated for 30 A breaker and use 10 AWG.

I’ve also seen threads of concern elsewhere about the 10 AWG wiring supplied for power input to the 50 amp Pro Tran. The responses have basically been “well, it’s UL listed & its a very short 10 AWG so it must be good.” Does that sound reasonable and does same apply for the 20 or so 12 AWG wiring on 20 amp circuits? I can see how the wire being short limits voltage drop for high current, but overheating of wires is a “per unit length” thing - I.e., a won’t a short wire & a long wire will heat up the same when too much current is pushed through?

 

[timselectric]

Thanks Tim! Any chance you could address the question on derating of the 20 12 AWG wires in 1” FMC (pasted below)

Much appreciated!

Here is my additional question - how does protran “get away with” quantity 20, 12 AWG + an 8 AWG neutral in a 1” FMC and use this for 20 amp circuits (all breaker positions in Pro Tran are rated for 20 amp). Should not the ampacity of the 12 AWG not be derated by 50% or more or am I not understanding how derating works?? Side Note - Slots A & B are rated for 30 A breaker and use 10 AWG.

I’ve also seen threads of concern elsewhere about the 10 AWG wiring supplied for power input to the 50 amp Pro Tran. The responses have basically been “well, it’s UL listed & its a very short 10 AWG so it must be good.” Does that sound reasonable and does same apply for the 20 or so 12 AWG wiring on 20 amp circuits? I can see how the wire being short limits voltage drop for high current, but overheating of wires is a “per unit length” thing - I.e., a won’t a short wire & a long wire will heat up the same when too much current is pushed through?

Any length of conduit that is less than 24", is considered a "nipple", and doesn't require any derating. Basically it is short enough that heat won't build up exponentially. It's kind of a code loophole, and you are allowed to stuff it as full as you want. But common sense should always apply.

 

[Aspendell Fire Pits]

So I guess that explains why they don’t sell a longer harness! I’m getting the impression that my Pro trans transfer switch is a bit on the “shady” side with regard to sizing.

That presents me with a problem because I need to “extend” my wiring harness between the Xfer SW & my main panel. The “whip” on the Protrans is just under 48” and I need about 84” of length because I can’t put my Xfer switch close enough to my main panel (it would be located directly under a basement scuttle window). Not sure of that location would be legal directly under the window but my gut tells me it is not a good idea for “common sense” reasons.

My idea was to put a big junction box and wire nut extensions between Protrans harness & main panel. This would add an extra splice in every wire between xfer switch and panel (which I am not thrilled about). Another option would be replacing the entire harness completely with new wires & spade connectors but this is where I got into the issue with correct wire sizing…

Any suggestions to make do with what I have OR a better xfer switch that would give me the ability to make the full 84” run without jury rigging things!!

 

[timselectric]

The “whip” on the Protrans is just under 48”

That's a different situation than the nipple loophole.
That's a factory harness, that doesn't have to follow the NEC.
They just have to get it through the UL listing process.
Extending it would void the UL listing. But an inspector may not catch it, if they aren't familiar with the product.

 

[Aspendell Fire Pits]

uhh boy...makes complete sense(??!!)

That's another reason (aside from burning my house down) that I didn't want to replace the harness with my own.

Thank you for your help - really do appreciate it!

 

[bhbaker220]

If you don't have AC in from the panel or subpanel to the 6000XP, and you're only connecting the 6000XP to the manual transfer switch (not to a subpanel or panel), don't you need to connect the neutral between the 6000XP and the ProTran?

 

[timselectric]

If you don't have AC in from the panel or subpanel to the 6000XP, and you're only connecting the 6000XP to the manual transfer switch (not to a subpanel or panel), don't you need to connect the neutral between the 6000XP and the ProTran?

In that scenario, yes.

 

[Aspendell Fire Pits]

Would also need N-G bond "on" in inverter, yes??

 

[timselectric]

Would also need N-G bond "on" in inverter, yes??

No
The N/G bond already exists in the main service panel.
There can only be one.

 

[Aspendell Fire Pits]

Oh yeah…I was thinking his transfer switch was “standalone” & not connected to a main panel, which was a really dumb thing to think!!