Identifying The Source of Electrical Hazards
How to Prevent a Potential Problem with a Circuit that is not Properly Grounded: The terminations to the outlet and the connections of the power cord should be positively identified and verified. The 4 wire 240 volt outlet should have a ground wire attached to it and if the outlet box is metal or has a ground screw terminal then there should be a ground wire attached there as well ending up with a bond of all ground wires within the outlet box.
Potential Problem with Electric Clothes Dryer or Circuit
Electrical Question: I wired a 4 prong outlet for my electric dryer service which is 30 Amp 240 Volt.
- I still must have a grounding problem because when the metal vent pipe touches another metal pipe in the basement it sparks. However, everything is attached correctly and the dryer is new.
- One thing I’m unclear about is that the dryer outlet is 4 prong which did not have an external connection for it to be grounded it to the junction box which is required.
- Could this be where the ground needs to be in addition to the ground on the dryer?
Background: Frank, a Homeowner from Ithaca, N.Y.
Thanks for your electrical wiring question Frank.
How to Prevent a Potential Problem with a Circuit that is not Properly Grounded
- This is a very dangerous situation, the circuit should be shut off right away. There should never be any sparking occurring around any electrical equipment as you are describing.
- The terminations to the outlet and the connections of the power cord should be positively identified and verified.
- The 4 wire 240 volt outlet should have a ground wire attached to it and if the outlet box is metal or has a ground screw terminal then there should be a ground wire attached there as well ending up with a bond of all ground wires within the outlet box.
- If after all of this is verified you continue to experience anything abnormal then I would turn off the circuit and notify whoever you purchased the dryer from or contact the manufacturer right away. If it is found that the dryer is OK then you have a stray voltage source in your basement that needs to be identified right away.
- This may be due to the lack of or problems with the ground system within the electrical wiring for the home. The ground system should be inspected and verified.
- Careful attention should be given to the separation between the ground and neutrals as required for circuits which are fed from the main electrical panel.
- It is always best to have a qualified licensed electrician provide an inspection of your home electrical system and make any necessary repairs to avoid any electrical hazards to you or your family.
- NOTE: All home electrical circuits must have a separate ground wire, and in cases where a neutral wire is required for 240 volt circuits such as the dryer and electric range, a separate insulated neutral wire must be included for what is known as a 4-wire circuit.
More about Home Electrical Circuits and Grounding:
Electrical Grounding Methods and Requirements
Listing of electrical codes for grounding with examples of electrical grounding codes for home electrical wiring.
Electric Clothes Dryer Circuit
3-Wire and 4-Wire Configurations for Clothes Dryers
See an electric dryer installation with a typical 220 Volt electric power cord wiring system. You may find yourself with either a 3-wire or 4-wire electric dryer, or a 3-wire or 4-wire outlet. Lets look a how the electric dryer is wired and what to do if your cord does not match the plug.
Be Careful and Be Safe - Never Work on Energized Circuits!
Consult your Local Building Department about Permits and Inspections for all Electric Wiring Projects.
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