electrical subpanel question

B

brackishdude

Member
This is for my new-to-me swimming pool pumphouse, but I believe addresses a few points applicable to folks running a new subpanel for their reefs. Just replace the word pool with tank everytime you see it below. It works. I swear.

I am replacing the simple on/off switch for the pool pump with a timer, and had to open the subpanel to run a neutral and ground out to the adjacent timer since the old switch was just a light switch wired into the hot for the pump circuit.

I discovered that the subpanel was wired with ground and neutral on a common bus, which, after consulting the internet, I discovered is not appropriate for a subpanel. The subpanel feeds several other devices/lights/etc already wired in inappropriately.

The problem is that the main feed only has the two hots and a neutral, no ground. It enters the pool pumphouse housed in a metallic pipe with metal fittings and comes underground from the house.

If I establish electrical continuity between the subpanel housing and the pipe as it enters the ground, can I just put in a new bus, screw it into the housing, and wire into it all of the ground wires currently on the neutral bus ? i.e. does the ground bus on the sub panel have to be in continuity with the ground wires of the main panel?

Thanks. Goooooooo reefs!!!
 
there is nothing wrong with neutral and ground being bonded on the same bus this is common practice in many installations. The ground is being provided by the metalic conduit as it should be securly bonded to the panel housing. If you wish to add another panel you can either run the ground back to the main panel or install a new ground by instlalling a ground rod.
 
and sorry to answer the rest of your question yes you can install a ground bus bar in the panel if there is one supported for you model and ground it like stated above with either a ground rod or use the existing conduit if the conduit is metal and is continuos back to the other panel then the panels will be of the same ground potential as the are "bonded" via the conduit. Hope this helps
 
IMO you should pound in a new ground rod for the pump house. For the cost you then have the peace of mind knowing it is 100% correct. It may be acceptable to rely on the conduit but would leave some doubt in the back of my mind.

I don't know the NEC well enough to quote but I didn't think you could run the ground and neutral to a common bus...

Tim
 
http://www.mikeholt.com/mojonewsarc...ding-versus-Bonding-Part-5-of-12~20050304.php


"What if there's no equipment grounding (bonding) conductor run to the building or structure disconnecting means? In such a case, you can bond the disconnecting means to the circuit grounded conductor (neutral). But this is only permitted only where there's no continuous metallic path between buildings and structures, and ground-fault protection of equipment isn't installed."
 
<a href=showthread.php?s=&postid=9537560#post9537560 target=_blank>Originally posted</a> by MC Lighting
there is nothing wrong with neutral and ground being bonded on the same bus this is common practice in many installations. The ground is being provided by the metalic conduit as it should be securly bonded to the panel housing. If you wish to add another panel you can either run the ground back to the main panel or install a new ground by instlalling a ground rod.
Click to expand...

NO!

YOU CAN NOT BOND NEUTRAL TO GROUND IN A SUBPANEL!!!!!!!! YOU MUST RUN A GROUND FEEDER TO THE MAIN PANEL AND ISOLATE NUETRAL FROM GROUND THE ENTIRE DISTANCE!

Some types of conduit can be used as the earth ground, if they are properly bonded. Some local codes prohibit this!
 
really then I guess the comercial electrical install that I just did that was passed by an electrical engineer and the city inspector is wrong?
 
<a href=showthread.php?s=&postid=9537582#post9537582 target=_blank>Originally posted</a> by MC Lighting
and sorry to answer the rest of your question yes you can install a ground bus bar in the panel if there is one supported for you model and ground it like stated above with either a ground rod or use the existing conduit if the conduit is metal and is continuos back to the other panel then the panels will be of the same ground potential as the are "bonded" via the conduit. Hope this helps
Click to expand...

If the building where the sub panel is located, is detached from the building where the main panel is located, then a ground rod should be set and attached only to the ground bar. This is a MUST (even if the conduit is bonded AND a ground feeder is run to the main panel). Notice again, that NUETRAL is NOT to be bonded to GROUND.

Bean
 
<a href=showthread.php?s=&postid=9541226#post9541226 target=_blank>Originally posted</a> by MC Lighting
really then I guess the comercial electrical install that I just did that was passed by an electrical engineer and the city inspector is wrong?
Click to expand...

I have no idea what "was passed" but what you said is not correct.

You can not bond neutral to ground in a subpanel. We can certainly get the NEC out if you wish.
 
i don't disagree that a ground rod should be driven it is a safety net you cannot beat and as stated is a cheap $38 insurance policy.
 
<a href=showthread.php?s=&postid=9541282#post9541282 target=_blank>Originally posted</a> by MC Lighting
i don't disagree that a ground rod should be driven it is a safety net you cannot beat and as stated is a cheap $38 insurance policy.
Click to expand...

It is required, not an option :) Actually, I beleive the new code states (2) ground rods need to be installed at detached locations. I would have to look that one up though.
 
ahhh wait I see where you and I are getting mixed up your assuming in the sub panel and I am assuming in the main panel the way I read his original post is sounded like the main panel and sub panel were one since many people call them subpanels if their is a main disconnect located at the meter probably should clarify main panel and sub panel.
 
<a href=showthread.php?s=&postid=9541306#post9541306 target=_blank>Originally posted</a> by MC Lighting
all I am asking is you are telling me that a city inspector, a electrical engineer and an C10 electrician are wrong?
Click to expand...

It happens every day... all day :) Give me 10 inspectors and 1) subsection of code, I can give you 10 different interpretations!

Honestly... without knowing the details of the wiring, I have no idea what your setup is and why or how it is approved. I do know that the NEC requires that sub panels have isolated ground and nuetral buses.
 
Lets step back here...

Thre are instances when the neutral and ground can be bonded at the sub panel. In those cases, NO OTHER metal or material capable of carrying current can connect the two buildings. THE PANELS MUST NOT BE IN THE SAME BUILDING. You will find the other criteria and relevant information in 250.32/B2 If the criteria are met, the neutral can be bonded and ground rods at the outbuilding must be set. We tend to not count any of these cases, because they are usually not a good idea. Instead we only look at scenarios where the sub-panel is fed by a EGC and therefore the neutral MUST be isolated.

Here is the PROBLEM (and why MOST inspectors and localities will NOT ALLOW IT). If the neutral becomes OPEN, then the grounding path back to the main panel will become the current carrying conductor. (In the OPS case, this would be the conduit). bad news to say the least. Ground rods are not effective means of protection. Yes they are a good idea, but should NOT be counted on to save your life. It is also not a good idea to have more than 1 grounding reference in a system.

In the case of the OP. The CONDUIT is a METAL PATH back to the MAIN PANEL (or building that houses the main panel) and therefore the NEUTRAL MUST BE ISOLATED. PERIOD!

Sometimes even things that "pass" code are not good ideas.

If you want to discuss "how many" certified and qualified people it takes to notice a mistake... we can have that discussion also.
Your setup may very well meet code.

Sorry to be so BOLD but 99% of the time subpanel NUETRALS should not be bonded to GROUND. The other 1% of the time, it is NOT a good idea.
 
:D
I thought I knew a little about neutrals and grounds. thanks for the confirmation Bean!

Tim
 
<a href=showthread.php?s=&postid=9541659#post9541659 target=_blank>Originally posted</a> by BeanAnimal
Lets step back here...

Thre are instances when the neutral and ground can be bonded at the sub panel. In those cases, NO OTHER metal or material capable of carrying current can connect the two buildings. THE PANELS MUST NOT BE IN THE SAME BUILDING. You will find the other criteria and relevant information in 250.32/B2 If the criteria are met, the neutral can be bonded and ground rods at the outbuilding must be set. We tend to not count any of these cases, because they are usually not a good idea. Instead we only look at scenarios where the sub-panel is fed by a EGC and therefore the neutral MUST be isolated.

Here is the PROBLEM (and why MOST inspectors and localities will NOT ALLOW IT). If the neutral becomes OPEN, then the grounding path back to the main panel will become the current carrying conductor. (In the OPS case, this would be the conduit). bad news to say the least. Ground rods are not effective means of protection. Yes they are a good idea, but should NOT be counted on to save your life. It is also not a good idea to have more than 1 grounding reference in a system.

In the case of the OP. The CONDUIT is a METAL PATH back to the MAIN PANEL (or building that houses the main panel) and therefore the NEUTRAL MUST BE ISOLATED. PERIOD!

Sometimes even things that "pass" code are not good ideas.

If you want to discuss "how many" certified and qualified people it takes to notice a mistake... we can have that discussion also.
Your setup may very well meet code.

Sorry to be so BOLD but 99% of the time subpanel NUETRALS should not be bonded to GROUND. The other 1% of the time, it is NOT a good idea.
Click to expand...



Bean,

Everything that you have stated is correct.

Inspectors make mistakes also but this is a common electrical installation that happens all the time. Most inspectors would catch this mistake.

Sub panels are not to have ground and neutral tied together.

Nuff said ?
 
<a href=showthread.php?s=&postid=9541390#post9541390 target=_blank>Originally posted</a> by MC Lighting
ahhh wait I see where you and I are getting mixed up your assuming in the sub panel and I am assuming in the main panel the way I read his original post is sounded like the main panel and sub panel were one since many people call them subpanels if their is a main disconnect located at the meter probably should clarify main panel and sub panel.
Click to expand...

No propblem at all.. and again, sorry if I sounded short. I just hate to see anybody get hurt or killed. The bonded neutral subject comes up quite a bit and there is a lot of very bad advice out there. It is safe to say that the only place you should ever bond neutral to ground, is in the main panel (or outby the main panel at the main disconnect). Sub panels, in almost all cases must (or would be better off) with an isolated neutral and ground :)
 
yup exactly See Bean this is why you and I debate well, thats the problem with the internet sometimes it is hard to understand a subtle detail. Yes lets keep people alive that would be a good idea....
 
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