Answer for USA, Canada and countries running a 60 Hz supply service.
There are a lot of different rules that apply to your question. Generally, when buried on residential property, conduit may be buried as little as 12 inches, measured from the TOP of the conduit to the SURFACE of the soil at its shallowest point.
When buried on commercial or industrial property the general rule is 18 inches, but that can vary depending on the voltage involved, what type conduit is used, and what the surface material is.
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As always, if you are in doubt about what to do, the best advice anyone should give you is to call a licensed electrician to advise what work is needed.
Before you do any work yourself,
on electrical circuits, equipment or appliances,
always use a test meter to ensure the circuit is, in fact, de-energized.
IF YOU ARE NOT ALREADY SURE YOU CAN DO THIS JOB
SAFELY AND COMPETENTLY
REFER THIS WORK TO QUALIFIED PROFESSIONALS.
To determine if you can fit six 350 MCM wires in a 3-inch conduit, you need to refer to the NEC (National Electrical Code) conduit fill tables. Generally, a 3-inch conduit can accommodate a limited number of large conductors, and 350 MCM wires may exceed the maximum fill capacity. It's essential to check the specific conduit fill calculations and local codes to ensure compliance and safety.
Yes, you can put UF (Underground Feeder) cable inside PVC conduit, but it is not typically necessary since UF cable is designed for direct burial. If you choose to use conduit, ensure that it is properly sized and that the installation complies with local electrical codes. Additionally, remember that the conduit must be sealed at both ends to protect against moisture ingress.
This depends on how many wires you need to put through the conduit. Typically you would figure out what size wire you need to handle a given load, and then find the smallest conduit you could possibly put those wires in. I'd actually need to know what type of conduit, also. Size your wire first, then your conduit. If you don't know how to size your wire, call an electrician. If you do it wrong you will start a fire. Once you've got your wire size, NEC Table C1 for EMT or C2 for PVC should head you in the right direction. ----If you do not understand the work well enough to accomplish it yourself properly and safely, don't try it. Consult a professional electrician, as they are proficient enough to do it properly and safely. When working on electrical circuits and equipment, make sure to de-energize the circuit you will be working on. Then test the circuit with a definitive means to make sure it is off (multimeter with metal tipped leads, voltage tester with metal tipped leads, etc., not a non-contact tester, which is non-definitive.)
NM-B (non-metallic sheathed cable) is not approved for use in conduit for exterior applications. It is designed for indoor use in dry locations and should not be exposed to moisture or adverse weather conditions. If you need to run electrical wiring outdoors, you should use a type of cable specifically rated for wet locations, such as UF (underground feeder) cable or use individual conductors in appropriate conduit. Always check local codes and regulations for specific requirements.
What kind of wire? If it's a power wire, why is the place wired with conduit? Commercial buildings must put all power wiring in conduit, so if you're planning to run romex in a commercial building, the answer would be "no", it's not permissible. If it's data wire, note that there may be some "crossover" interference if the data wire follows a power wire for very much distance. It's usually not a problem to cross a conduit and tie to it, but it's generally recommended that you not tie data cable to conduit.
If your septic line is deep enough, you can.
No, electrical wiring should not be placed on the ground in a crawlspace. It should be properly installed and secured to walls or studs to prevent damage and reduce safety hazards. Wiring on the ground can be exposed to moisture, debris, and pests, which can lead to potential electrical issues.
as deep as they need to go
Yes, it is generally not recommended to put Romex wiring inside conduit as it can cause overheating and potential safety hazards. Romex wiring is typically designed for use without conduit.
It is easy to put a 2-inch long piece of conduit that is less than half an inch in any cross-sectional measure into a half-inch conduit.
to prevent live conduit in case of short circuit
How deep do they put telephone poles in the ground
The usual formula is this; for every foot above ground you put 1/2 foot in the ground.
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Yes, you can put UF (Underground Feeder) cable inside PVC conduit, but it is not typically necessary since UF cable is designed for direct burial. If you choose to use conduit, ensure that it is properly sized and that the installation complies with local electrical codes. Additionally, remember that the conduit must be sealed at both ends to protect against moisture ingress.
Before it hits the ground
No, each conduit should only contain wires from the same circuit. Mixing circuits in a conduit can lead to interference and safety hazards. It is always best practice to keep conductors of the same circuit together to prevent potential issues.