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-   -   Wiring main panel without dying (http://www.diychatroom.com/f18/wiring-main-panel-without-dying-163717/)

Maxian 11-17-2012 04:43 PM

Wiring main panel without dying
 
Hello all,
I'm wiring a spa and have a few questions regarding the main panel.
I was under the impression that the neutral and ground wires have to be separate ?
The spa sub panel has two bars in it. A large one the GFI breaker is hooked to and a smaller one in corner.
I looked in my main panel today and notice that the grounds and neutrals are on the same bar.
I suppose there is no reason to use separate bars in the sub panel because they will just end up in the same place at the main panel.
Correct ?
I'm running 3 #6's and an #8 ground.
Spa is a 3 wire hookup ( hot x2 and ground )
Am I missing something regarding this ?
Can somebody please explain the correct way to wire the main panel and the sub panel with GFI by the hot tub.
Maybe point me to someplace with pictures.

P.S.
If I shut the main breaker off, is the panel "cold" except where the main breaker is "fed"??

Thanks :)

jrclen 11-17-2012 05:08 PM

The grounds and the neutrals can be on the same terminal bars in the main panel.

Grounds and neutrals must be separated in the spa disconnect. Are you sure there is no neutral in the spa?

Yes the main panel will be dead except for the conductors feeding the main circuit breaker when the main is turned off.

This site may help you.

http://www.spadepot.com/spacyclopedi...FYs7Mgodz2UALw

rjniles 11-17-2012 05:59 PM

IMHO Wiring a spa is not a great place to start your DIY electrical work. Hire a pro.

Stubbie 11-17-2012 06:50 PM

1 Attachment(s)
Quote:

Originally Posted by Maxian (Post 1054531)
Hello all,
I'm wiring a spa and have a few questions regarding the main panel.
I was under the impression that the neutral and ground wires have to be separate ?
The spa sub panel has two bars in it. A large one the GFI breaker is hooked to and a smaller one in corner.
I looked in my main panel today and notice that the grounds and neutrals are on the same bar.
I suppose there is no reason to use separate bars in the sub panel because they will just end up in the same place at the main panel.
Correct ?
I'm running 3 #6's and an #8 ground.
Spa is a 3 wire hookup ( hot x2 and ground )
Am I missing something regarding this ?
Can somebody please explain the correct way to wire the main panel and the sub panel with GFI by the hot tub.
Maybe point me to someplace with pictures.
P.S.
If I shut the main breaker off, is the panel "cold" except where the main breaker is "fed"??

Thanks :)

Spa installs are quite common here so I made this drawing in order to be a guide to a safe installation ... see if it helps and then ask your question after looking at the drawing.

To answer a few questions ... in the main panel where the 1st means of whole house disconnect from the utility exists your neutral and grounds are landed to the same neutral bus. At the spa panel you keep them electrically separated. You still need a neutral ran to the SPA disconnect even if the spa is 240 volts

Maxian 11-17-2012 09:57 PM

Maybe I'm just not getting it, but why are we separating the ground and neutral only at the spa panel ?
So the ground bar is "bonded" to spa panel, so what ?
We have a metal ground bar screwed to a metal sub panel, screwed to a stucco wall. I don't see how this
is accomplishing anything.
I'm not being rude, I just don't get it.
Thank you

Missouri Bound 11-17-2012 10:16 PM

Code requires that the neutral and ground must be seperated at a sub panel. Your spa panel is effectively a sub panel.

darren 11-17-2012 10:42 PM

Since you asked there is no ground at your spa, you have a bond with two hots and a neutral. Under normal operation there is no current on your bond only on the hots and the neutrals.

If you were to tie the neutral and bond together at your spa panel this will allow the bond conductor to carry current, which it is not designed to do. The bond is there to carry fault current only and thus is sized smaller then your other wires.

At your main panel the neutral gets grounded(that is why the neutral is called the grounded conductor) so in that panel it does not matter where the bond and neutrals end up since they are basically the same point in the panel. In every service the neutral gets grounded at the first panel or disconnect and every where after that the bond and neutral are seperate.

Stubbie 11-17-2012 11:54 PM

3 Attachment(s)
Quote:

Originally Posted by Maxian (Post 1054783)
Maybe I'm just not getting it, but why are we separating the ground and neutral only at the spa panel ?
So the ground bar is "bonded" to spa panel, so what ?
We have a metal ground bar screwed to a metal sub panel, screwed to a stucco wall. I don't see how this
is accomplishing anything.
I'm not being rude, I just don't get it.
Thank you

It's likely because you are thinking earth/ground which has nothing to do with separating neutral and ground at your spa-panel. 'Ground' in your case is more correctly called equipment grounding and bonding. The green insulated wire in the diagram is the EGC (equipment grounding conductor). this is non current carrying wire intentionally installed to bond all metal likely to be energized during a fault to metal to the 'effective ground fault path'. It never carries current in normal operation of your premise electrical system. However it does carry the current when a fault to bonded metal occurs. If you were to bond the egc to the neutral anywhere but the main panel (service equipment) then you would be providing for a parallel path for neutral current as it returns to the main panel and then back to the center tap of the utility transformer. Current does not go to earth as many people think ... it seeks its source. If we bond the egc to the neutral at the spa-panel two things will happen the neutral current will pretty much split between the egc and the neutral and any metal that is bonded by the egc will be energized. The only time we want current on the egc and metal enclosures is when there is a fault to metal like a hot bare wire touching the metal of the spa panel. If this were to happen then the fault current transfers to the egc and the egc will complete a circuit with the transformer via the utiltiy neutral due to the bonding of neutral and ground at the main panel. Remember the only way back to the source (transformer) that is low impedance and resistance for ground fault current is the utility neutral. This no load completed circuit for the fault current allows massive amperage to flow on the fault circuit and trips out the circuit breaker. Study a few of these drawings below and hopefully you will understand that we only bond neutral (a current carrying wire that is part of an energized 120 volt circuit) with the egc at the main panel where there is only one path back to the source.

Also if you bond the neutral to the ground in your spa panel the gfci will immediately trip ....

Billy_Bob 11-18-2012 10:11 AM

Quote:

Originally Posted by Maxian (Post 1054783)
Maybe I'm just not getting it, but why are we separating the ground and neutral only at the spa panel ?
So the ground bar is "bonded" to spa panel, so what ?...

Electrical codes take ALL SITUATIONS which might possibly happen into consideration.

Or worded differently, in the past there have been electrical problems, which in turn, have caused people to be electrocuted. And modern electrical codes incorporate clever wiring designs and devices which prevent these things from happening in the future!

One of those problems from the past is that wires get cut or will stop working due to a poor connection. People drill holes in walls or dig or saw and cut wires. And wire connections work themselves loose or corrode when not properly installed and maintained.

And when just ONE CERTAIN WIRE (like a combo ground/neutral wire) is cut or loses its connection, then you have BIG trouble!

What would happen to a metal "grounded" case in that situation? (Becomes hot!)

Best to follow the code. All the rules are there for a reason. They are to protect you and your family...


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