Is wiring a 240 volt heater from a sub panel different from wiring it to the main panel?


Since the neutral and ground are isolated in a sub panel, is wiring a 240 volt heater from a sub panel different from wiring it to the main panel?

No, as long as you land the ground wire on the ground bus of course -- but that's a caveat when wiring anything to a subpanel. (I'd run it using /3 NM so that there's a neutral run to the heater in case it's needed for outlets on a baseboard setup or something like that...and in that case, you also have to remember to land the neutral wire on the neutral bus, but again, that's just like any other circuit.)

The hots hook up just like any other 220V circuit.

February 18, 2016 02:06 AM

I'll add this as well: 240V doesn't rely on the neutral anyway. Although some loads require running 2 hots and a neutral, it isn't there to get 240. Like the last answer said though, it's all wired the exact same way.

Isolation of the neutral and ground is just to prevent any power from running the...

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Better trying to run a 240 Volt appliance on 120, than the other way around. You better change it to a 240 Volt circuit ASAP. For one thing, water heaters (240 V - I've never seen a 120 volt outside of a camper or small trailer) require two Ungrounded conductors, generally with a GROUNDING conductor. On a 120 Volt circuit, you have one Ungrounded (hot) conductor, and one GroundED conductor (hopefully with a Grounding, or more correctly, an Equipment Grounding Conductor). The Ampacity required to run a 240 V appliance at 120 V is twice what is required for 240 V. (Using a 30 Ampere Load as an example, that would be a 7,200 Watt appliance. To provide 7,200 Watts to a 120 V appliance requires 60 Amps.) The wiring and the overcurrent protection are not going to allow the heater to pull its full load, or if it does, either the conductors or the breaker will have to give; hope that it is the breaker. You will need a...

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Answer for USA, Canada and countries running a 60Hz supply serviceLIFE SAFETY WARNING! [disclaimer]

Electricity is dangerous!

You can be injured or killed!

Improper installations can cause fire, injury and death!

Should you be doing this yourself?)

This is one of those questions - if you know this little, you shouldn't be doing what you are planning...

No disrespect intended, but this is SO basic that it suggests you have not studied the subject at all!

There are many good reference books and course books to study from.

Don't do it!
If you do this work yourself, always turn off the power
at the breaker box/fuse panel BEFORE you attempt to do any work
always use a meter or voltage indicator
to insure the circuit is, in fact, de-energized.IF YOU ARE NOT ALREADY SURE YOU CAN DO THIS JOB

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There is no need to rewire the internal of the heater!

Just bring in the electrical supply to the heater, it can be either 120 or 240 volts.

If the heater you have is like the picture associated with your post, then all then have to do is change the supplied plug from 240 to 120. It comes pre set for 240. That plug is inside the cabinet.

If any other brand, then you need to change the wires at the transformer of the heater. All heaters need to be supplied with primary voltage: 120 or 240. Then the control system is supplied with secondary voltage out of the transformer. The secondary voltage is no more than 28 volts. and these wires are normally colored as blue or yellow.

Secondary power is already wired within the heater. NO need to change where they are. You will only need to deal with the Primary wiring.

There are many varieties of transformers that transform high primary voltage to a low secondary voltage of 28 volts. and these transformers...

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Yes, kinda figured Romex was installed. Thanks for the confirmations.

You would have the following 2 choices:

1) Install a lower wattage heater such as a 5kW. This size heater only requires a 30 amp double pole breaker using 240 volts and 10 AWG Copper conductors of which you already have in place. You would just need to de-install the existing receptacle and extend the 2 hots and 1 equipment ground up to the ceiling area and then transition over to Greenfield flex conduit to allow for heater swivel adjustment. All ceiling mounted heaters are hard-wired. I've never come across a cord & plugged unit on a ceiling mount unit.

Farenheat is a quality brand and so is Comfort Zone. They both manufacture a 5kW heater. Both heaters have good customer reviews as well. I've installed a couple of the Farenheat models and my customers were happy with the product and performance.

See links shown...

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What to look for in the breaker box

Unless your home is very old and has never had its electrical service updated, it has 240-volt service from the street and into the main service panel as well.

Nearly every service panel has two 120-volt wires and one neutral wire running to it from the utility company. Each wire powers one “bus” (copper vertical leg) inside the main service panel. That’s why you usually see two columns of breakers (or fuses) when you open your service panel door. The common 120-volt circuits that power everything from your lava lamp to your vacuum cleaner are powered from one of those two buses. The standard 15- or 20-amp circuit breakers work by clipping onto one of the buses. Then the circuit’s hot (red or black) feed wire is clamped to the circuit breaker, while the neutral (white) wire and bare copper ground wire are clamped to the common neutral bar.

The way you get a 240-volt circuit is simple. A “double-pole” circuit breaker is...

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Before circuit breakers, mankind had fuses. They are single-use current interrupter with a component that melts if the current traveling through a circuit grows to excessive levels; thus, the fuse is used up and the electrical circuit remains protected and intact.

So, what do fuses do exactly? Well, fuses are usually just thin pieces of wire enclosed in heat-resistant glass or some other type of material. These fuses are plugged into the circuit and act as a conduit for the electricity flowing through it. You can think of fuses as a bridge that allows current to travel across the circuit. The wire (or other component) in the fuse is designed to tolerate a certain level of current. When the current flowing through the circuit experiences a surge, the wire melts or disintegrates, creating a gap that the current cannot cross. Going back to the bridge metaphor, the bridge has a weight limit. A surge of current is like a really heavy truck that caused the bridge to collapse....

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Electricity is responsible for running pumps and motors, ignites gas heaters, and operates controls. When major renovation or installation of electrical circuits is required, call a professional electrician and subcontract the job. When troubleshooting short circuits or other specialized electrical problems, an electrician will solve and repair it faster than you can, so again, call a professional and let him do his job.

Water technician and electrician is required to make basic electrical connections, troubleshoot underwater lights that won't work, switch appliances from 110 volt to 220 volt, and so on. Understanding the basic concepts of how electricity works, is controlled, and is conducted, will keep you both safe and profitable.

Electrical Terms

Electrical Terms definitions are as below

Amperage (amps) is the term used to describe the actual...

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When troubleshooting electrical problems in a house, you can avoid watts of frustration by learning or reviewing things about your electrical system. When you have learned enough, you'll be ready to go to the page for Troubleshooting these problems in your own home. Disclaimer.

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Electricity flows to your lights and appliances from the power company through your panel, its breakers, out on your circuits and back. Here is a schematic picture of all the major parts of your home electrical system.

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Getting electrical signals from point A to point B is pretty standard thing...Put a piece of copper wire between A and B and the job is done. A century of development has left us with increased specialization in wiring, connection devices, and everything in between point A and B. "Mil-Spec" or military specification, has become the buzz-word in motorsport electrical harness construction. Actually motorsport wiring has developed it's own specialized connectors but it's still largely constructed from aerospace components.

Perhaps "Race-Spec" will become the new buzz-word....Probably not with the trillions of dollars spent on drones, F22's, and commercial aircraft.

This is not a definitive guide on building wiring harnesses as this could encompass two wheels, four wheels or no wheels. It does give you a perspective on motorsports ecu wiring and provides access to further literature for you to study and make your own decisions. We build ecu wiring...

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So you are wanting to convert volts, amps, and watts. This is a rather simple conversion you can do with a calculator, you don’t need any special devices, but there are some devices out there that will convert volts, amps, and watts for you. Every electrical device in your home should have it’s voltage and amperage or voltage and watts printed on it. If not you will need to use a multimeter to find the voltage and amperage or voltage and watts.

But for those electrical devices in your home that have volts and amps or volts and watts printed you can convert amps to watts or convert watts to amps depending on what measurement you want.

If your electrical device in your home has the voltage and amperage printed on it you can convert this to watts by multiplying the voltage and amperage.

Voltage * Amperage = Wattage

So if you have a laptop that has 20 volt 4.5 amp printed on the power supply then that power supply is capable of using 90 watts.


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