I've built a pool house 160 feet from the main house. I ran #2 Aluminum 4 wire (2 hots, 1 common, 1 ground)from the main to the pool house on a 100 amp breaker. The pool house subpanel has a solid bar connecting the common to the ground bar. The main house is grounded. Should I add a ground the subpanel box or rely on the subpanel being grounded back to the main house?
Ground Rods
- Thread starter intoo
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- Massachusetts
Re: Ground Rods
1) You must connect to or install a grounding electrode at this remote building.
2)You can not connect the grounded conductor to the grounding conductor from the main panel at this remote panel.
You might be able to abandon the grounding conductor from the main panel and just use the grounded conductor for both the neutral and grounding duties.
To do this there can not be any metallic paths between the two buildings that are bonded to the electrodes, like a water pipe.
1) You must connect to or install a grounding electrode at this remote building.
2)You can not connect the grounded conductor to the grounding conductor from the main panel at this remote panel.
You might be able to abandon the grounding conductor from the main panel and just use the grounded conductor for both the neutral and grounding duties.
To do this there can not be any metallic paths between the two buildings that are bonded to the electrodes, like a water pipe.
Re: Ground Rods
I read a different article that said I could avoid grounding the subpanel if I connected to an "isolated nuetral/common" in the subpanel. I don't know what that means, assuming that all subpanel boxes have the common and ground bars internally connected.
If I understand your advise, I didn't need to run 4 wire? I do have a water line between the two buildings in 1" schedule 40 PVC. Does this affect the option?
Thanks for reponding.
I read a different article that said I could avoid grounding the subpanel if I connected to an "isolated nuetral/common" in the subpanel. I don't know what that means, assuming that all subpanel boxes have the common and ground bars internally connected.
If I understand your advise, I didn't need to run 4 wire? I do have a water line between the two buildings in 1" schedule 40 PVC. Does this affect the option?
Thanks for reponding.
Re: Ground Rods
250.32. If you DO NOT have any metalic pathways between the two structures, you can use 3-wire, bond the grounded conductor to a ground electrode. Basically just like a service. However if you have any metallic pathways, you must use 4-wire and NOT bond the grounded conductor.
IMO the safest way is to assume there is a metalic pathway and use a 4-wire setup.
250.32. If you DO NOT have any metalic pathways between the two structures, you can use 3-wire, bond the grounded conductor to a ground electrode. Basically just like a service. However if you have any metallic pathways, you must use 4-wire and NOT bond the grounded conductor.
IMO the safest way is to assume there is a metalic pathway and use a 4-wire setup.
T
taylorp
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Re: Ground Rods
intoo:
I almost always plan on running 4 conductors in a situation like this because of the unknown parallel paths that might exist between one building and another. You should remove the solid bar connecting the common (neutral) to the ground bar. Attach your insulated neutral to the neutral buss (common), attach your "ground" (EGC) wire to the ground bar, making sure that your ground bar is bonded to your subpanel. Now you need to run an GEC (grounding electrode conductor) sized according to Table 250.66 from your ground bar to your grounding electrode selected from 250.52 and installed at your new pool house. See 250.32(B)(1) which describes what you should do since you already have the 4 conductors.
intoo:
I almost always plan on running 4 conductors in a situation like this because of the unknown parallel paths that might exist between one building and another. You should remove the solid bar connecting the common (neutral) to the ground bar. Attach your insulated neutral to the neutral buss (common), attach your "ground" (EGC) wire to the ground bar, making sure that your ground bar is bonded to your subpanel. Now you need to run an GEC (grounding electrode conductor) sized according to Table 250.66 from your ground bar to your grounding electrode selected from 250.52 and installed at your new pool house. See 250.32(B)(1) which describes what you should do since you already have the 4 conductors.
Re: Ground Rods
Thanks to all that have responded. With regard to parallel paths, I did install a SECOND conduit from the house to the pool house in the same ditch 4 feet underground. The second conduit contains a coaxial cable and telephone line. Also, from the pool house, I'm wiring an outside hot tub having a 60 amp designated GFCI breaker about 12 feet from the pool house (if this matters). If the second conduit line constitutes a parallel path, my plan is as follows.
I connect all four wires at the main house panel.
I isolate the common bar in the subpanel.
I install a properly sized ground rod at the subpanel to the grounding bar.
Is this acceptable?
Again, thanks for your assistance.
Thanks to all that have responded. With regard to parallel paths, I did install a SECOND conduit from the house to the pool house in the same ditch 4 feet underground. The second conduit contains a coaxial cable and telephone line. Also, from the pool house, I'm wiring an outside hot tub having a 60 amp designated GFCI breaker about 12 feet from the pool house (if this matters). If the second conduit line constitutes a parallel path, my plan is as follows.
I connect all four wires at the main house panel.
I isolate the common bar in the subpanel.
I install a properly sized ground rod at the subpanel to the grounding bar.
Is this acceptable?
Again, thanks for your assistance.
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