Sub-panel Installation Questions

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Old 06-03-17, 10:27 PM
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Sub-panel Installation Questions

Hi guys,

I need some advice on how to install a generator transfer switch and sub-panel out on our shed that houses our water pump and water softener and water tank.

Currently, the water pump(240v) is connected via a wire that goes to a fixture switch in the shed near the pump, from the switch, it then goes back to a wire that goes directly into a 20amp breaker in the MAIN panel box that is mounted outside on a post.

I bought a 30amp generator transfer switch (model CSR302), and I would like to wire that in so I could power the well water pump during power outages.

But then, I also got into thinking that maybe I should also might as well install a sub-panel/breaker box in the shed just so I will have the ability to wire in some electrical outlets and lights if I decide to in the future.

My questions,

1st: Do I need to install a grounding rod for the breaker sub-panel / breaker box that I install in the shed? (looking from the sub-panel wiring diagram pinned thread, if I understand it correctly, I would need to put a grounding rod for my application)

2nd: The transfer switch I bought has a sticker that states "for connection of nonseparately derived(floating neutral) systems only. I tried reading up on it but can anybody explain it to me in relation to my application?

Location is in Florida btw.

Hoping to see all you guy's input. Thanks!

BG
 
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  #2  
Old 06-04-17, 07:08 AM
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Currently, the water pump(240v) is connected via a wire that goes to a fixture switch in the shed near the pump
Is this fixture switch double pole? If not, you should use double pole or a double pole disconnect switch (simple A/C disconnect switch is very cheap.) 240V uses 2 poles and regular light fixture switches are single pole. If only one pole is disconnected, the other pole is still sending live voltage down to the pump.

Do I need to install a grounding rod for the breaker sub-panel / breaker box that I install in the shed
?

I'm not 100% sure since the main panel is on the pole instead of in the building. I think it would be a good idea to have one even if not needed.

The transfer switch I bought has a sticker that states "for connection of nonseparately derived(floating neutral) systems only
Some generators have neutral tied to the chassis (ground) of the generator and some generators have neutral not tied to chassis (floating).
Most transfer switches only switches 2 hot wires and does not switch neutral and ground.

By code, neutral should be bonded at only one location (usually in the main panel) and if you connect generator with neutral bonded to the ground, now you end up with neutral to ground bond at 2 locations.
This is why they want floating neutral generator.

It is easy to modify the generator to floating neutral if your's isn't floating. Just open the panel and disconnect bonding wire between neutral and ground.
 
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Old 06-06-17, 09:19 PM
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Yes. Fixture switch is double pole.

That's what I was thinking but I just didn't know if too much grounding would be a bad thing in this case since I'm basically hooking a sub panel directly from the MAIN power box on a pole outside the house.
 
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Old 06-07-17, 09:23 PM
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So I'm just wondering, what would be the problem with this setup? (Ground wire not connected by subpanel but subpanel has its own ground rod?

Neutral is still only bonded at the main service panel...

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Old 06-07-17, 10:18 PM
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Ground wire not connected by subpanel but subpanel has its own ground rod?
Not sure what you mean by that but you need both a ground rod, GEC, and a ground wire, EGC from the supplying panel. GEC is for dissipating atmospheric charges. The EGC is a low resistance path to trip a breaker if there is short to a metal chassis or case.

The feed from the main panel and the feed from the house would go to the inputs of the transfer switch. The subpanel would go to the output of the transfer switch. This would allow you to choose either house power or generator power and keep the house power isolated from the generator power.

This is for a three pole transfer switch but what you are doing is the same except the neutral isn't switched.

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Old 06-08-17, 08:17 AM
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Sorry, it was late when I wrote that and brain was malfunctioning. I'm not sure I'm following.

The picture/diagram I modified, I erased the green wire(grounding conductor) that connects the Main Service panel to the Sub-panel, but the sub-panel still has it's own grounding rod to ground the sub-panel chassis.

I'm just trying to understand how this system would act differently from the original unmodified diagram, since I don't see ,for the life of me, and thus I feel like I'm missing something here.
 
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Old 06-08-17, 08:56 AM
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The grounding conductor back to the panel is to trip the breaker should a short occur. The rod will not do that.
 
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Old 06-08-17, 09:11 AM
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Took a while but NOW I do see what you all are saying. I knew I was missing something. Thanks!
 
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Old 06-10-17, 01:29 PM
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"It is easy to modify the generator to floating neutral if your's isn't floating. Just open the panel and disconnect bonding wire between neutral and ground."

So, I checked my Yamaha YG6600DE Generator to see if it is a bonded or unbonded neutral. I used my multimeter and checked for continuity between ground and neutral ports on the NEMA 14-30 - 240v twist lock plug. I had continuity between them. I also had continuity between ground to chassis(obviously), and then also have continuity between neutral @ 14-30 port TO chassis.

This tells me that I have a bonded neutral correct?

Now I opened up the generator panel and I don't see a bonding wire. Do I just remove the ground cable on the Nema 14-30 plug(then that would make it open neutral?)


NVM, I found where they bonded the neutral and ground. It was right inside(behind) the actual generator and not behind the panel. Was a short green wire connected to a stud with the neutral and then to generator chassis. Took the short wire out and now it's a floating neutral generator.
 

Last edited by bford17; 06-10-17 at 03:27 PM.
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Old 06-10-17, 06:43 PM
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Need expert advice.

So I finally, got done with wiring our well pump to the transfer switch. The problem is, I think I have an issue/problem/mistake so I need expert advice to check and see if I wired it correctly or not.

My main concern is the grounding, mainly since the well pump is sitting on a well tank, that is basically sitting on the soil/ground - thus is basically grounded in my mind like having a grounding rod connected directly to the pump.

All the diagrams that I've seen, I can only be grounded at the main service.

Experts please advice. Thanks.

Note: Wiring from main panel/breaker to shed/transfer switch was original wiring that I had to work with.

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Old 06-10-17, 08:27 PM
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But then, I also got into thinking that maybe I should also might as well install a sub-panel/breaker box in the shed just so I will have the ability to wire in some electrical outlets and lights if I decide to in the future.
You must have four wires from the main panel to install a subpanel. You can't use a bare ground for neutral which your diagram shows. You seem to be using xx-2 cable. It must be xx-3 Uf cable or four wires in conduit.
 

Last edited by ray2047; 06-10-17 at 09:05 PM.
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Old 06-10-17, 09:21 PM
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I ended up not installing a sub-panel from the Main Service Panel. The main panel in the diagram I just made is the Main Service Panel on a post outside the house then it goes to the transfer switch.

Yeah that's what I thought I should have but apparently the previous owners did not put the correct wiring to to begin with. I was already alarmed about the wiring(i immediately thought they used the wrong wire that I'm gonna have to deal with) when I saw that wire they used but since I needed to do this now just so we can be ready to for the hurricane season.

As it sits, that's pretty much the same connections it had before I installed the transfer switch(besides the fact that I can now plug a generator when absolutely needed).

I guess, I'll have to replace and pull new wiring out to the shed to correct it.

I know it varies by location but how much would you guys say it would be to get an electrician to pull the current wiring out and replace it with 10ga 3 UF about 25 ft. I just I'm hesitant to do the wire pulling myself since wire to pump needs to be done pretty much without a hitch that same time since its our main source of water for the whole house. Other minor reasons is I don't have to a fish tape(I can always buy one), never done it and might encounter unforeseen issues - which is probably most likely since I have a feeling that the previous people that did this, did so half-assed.
 

Last edited by bford17; 06-10-17 at 10:20 PM.
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Old 06-10-17, 10:23 PM
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The hardest part in running a new line is digging the trench. You shouldn't need an electrician if you want to do it yourself. If there is conduit there you may be able to reuse it. If you go with the first option, a new ditch and cable, you can wire everything up without touching the pump then just transfer the pump power connection. You would not need a disconnect switch at the pump as a breaker in the sub panel would serve that purpose. With everything set the pump would only be down for how long it took to move the pump cable from the current switch to the breaker.
 
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Old 06-10-17, 10:37 PM
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Well, what I was thinking was using the same conduit that they have buried that houses the current wire that I want to replace.

I just don't understand how they have it layed out because coming from the main panel, it seems that it goes into a large pvc conduit, but then when I look at the end of it, at the well/shed, it comes out of a flexible conduit that's buried. I don't know if its all 1/2" flexible conduit or they just added it down the line along with a pvc conduit, or what.

One thing I just thought of is that I could possibly tie the new 10ga 3 wire + ground uf and use the old wiring to pull it...I don't know if that would work though. Really, I'm just afraid of not having water at the house because I couldnt finish trying to pull new wiring out to the shed.

And yes, you're right about that! If I did go with digging/running a new conduit and pull new correct wires, then I could technically have everything running and pretty much not have downtime transferring the wiring to the pump.

I've actually thought about that too since I really did want to install correct wiring so I could install my sub-panel @ the shed and run a couple lights and a 120v outlet, along with the well pump.

Hardest thing for me I guess is figuring out the connections for conduits to breakers and such...I had to run to home depot multiple times because I didn't know much about conduit/subpanel connectors.
 
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Old 06-10-17, 11:55 PM
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from the main panel, it seems that it goes into a large pvc conduit, but then when I look at the end of it, at the well/shed, it comes out of a flexible conduit that's buried. I don't know if its all 1/2" flexible conduit
" conduit will handle four #10 THWN but I would not try using 10-3 UF cable. First though you need to do some digging to see what you really have.
 
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