Using MTW-THHN-THWN-2 for direct burial
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Re: Using MTW-THHN-THWN-2 for direct burial
Normally you would not use these wire types for direct burial.
However, if it is okay to use a direct-buried bare copper wire in your situation, (which I assume it is). - then what would be wrong with using a green-insulated wire. If the dirt ruins the insulation & the insulation falls off, you then have a bare copper wire.
What do others think?
Normally you would not use these wire types for direct burial.
However, if it is okay to use a direct-buried bare copper wire in your situation, (which I assume it is). - then what would be wrong with using a green-insulated wire. If the dirt ruins the insulation & the insulation falls off, you then have a bare copper wire.
What do others think?
Re: Using MTW-THHN-THWN-2 for direct burial
Bare copper wire can only be used in soils that will not corrode it. Some soils have a source of sulfur and sulfur metabolizing bacteria that generate sulfuric acid. I have not lived in such an area where the topsoil was affected but there are some well waters here in Ohio that have this problem. In these instances all water heater warranties are void. If you want metal plumbing to not be eaten you need an acid neutralizer which is a tank that is filled with crushed marble and your well water goes through it.
You can also have the same problem on farms because of bacteria that metabolize urea to form carbon dioxide and ammonia. Ammonia readily corrodes copper and steel hence the requirement for insulated equipment grounding conductors and neutrals on farms.
However. the bare copper wire might actually be a good idea under other circumstances where procuring a good ground is difficult. To be efrective as a supplementary grounding electrode the raceway that supplies the underground wiring needs to be nonmetallic.
[ April 17, 2005, 03:38 AM: Message edited by: mc5w ]
Bare copper wire can only be used in soils that will not corrode it. Some soils have a source of sulfur and sulfur metabolizing bacteria that generate sulfuric acid. I have not lived in such an area where the topsoil was affected but there are some well waters here in Ohio that have this problem. In these instances all water heater warranties are void. If you want metal plumbing to not be eaten you need an acid neutralizer which is a tank that is filled with crushed marble and your well water goes through it.
You can also have the same problem on farms because of bacteria that metabolize urea to form carbon dioxide and ammonia. Ammonia readily corrodes copper and steel hence the requirement for insulated equipment grounding conductors and neutrals on farms.
However. the bare copper wire might actually be a good idea under other circumstances where procuring a good ground is difficult. To be efrective as a supplementary grounding electrode the raceway that supplies the underground wiring needs to be nonmetallic.
[ April 17, 2005, 03:38 AM: Message edited by: mc5w ]
aelectricalman
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Re: Using MTW-THHN-THWN-2 for direct burial
You can only use it for direct burial if it is listed for Direct burial. THWN is not listed for direct burial. It is listed for damp area locations. Hope this helps alittle.
You can only use it for direct burial if it is listed for Direct burial. THWN is not listed for direct burial. It is listed for damp area locations. Hope this helps alittle.
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