Paralleling wiring to supply water heater, stove... ?

Thread Starter

Externet

Joined Nov 29, 2005
2,232
Hi.
Can two paralleled AWG#14 'romex' wires be installed instead of one AWG#10 'romex' to feed a water heater or an electric stove from a 30 Ampere breaker ?
What is the AWG# equivalent paralleling two AWG#12; or two AWG#14 ?
 

MisterBill2

Joined Jan 23, 2018
18,934
Powering a single load from separate breakers is a sure way to be able to overload the single powered connection remaining powered. So I would power them both trough one breaker.
Doubling conductors is claimed to increase the current capacity two copper wire sizes, so that two #14 wires would be good for 30 amps and two #12 wires would be good for 40 amps. That works for identical wires in a conduit, I am not sure how well it would be accepted if it is done with two conductor "duplex" cable.
For an electric water heater it might be possible to power each heater element from a separate breaker as an acceptable alternative. BUT it will require changing connections inside the heater. That is simple but not obvious how it is done.
 

nsaspook

Joined Aug 27, 2009
13,418
Powering a single load from separate breakers is a sure way to be able to overload the single powered connection remaining powered. So I would power them both trough one breaker.
Doubling conductors is claimed to increase the current capacity two copper wire sizes, so that two #14 wires would be good for 30 amps and two #12 wires would be good for 40 amps. That works for identical wires in a conduit, I am not sure how well it would be accepted if it is done with two conductor "duplex" cable.
For an electric water heater it might be possible to power each heater element from a separate breaker as an acceptable alternative. BUT it will require changing connections inside the heater. That is simple but not obvious how it is done.
Note that I said they must trip together (mechanically or electrically ganged), so if any single wire is overloaded, all breakers, as a unit, trip.
 

WBahn

Joined Mar 31, 2012
30,234
Powering a single load from separate breakers is a sure way to be able to overload the single powered connection remaining powered. So I would power them both trough one breaker.
Doubling conductors is claimed to increase the current capacity two copper wire sizes, so that two #14 wires would be good for 30 amps and two #12 wires would be good for 40 amps. That works for identical wires in a conduit, I am not sure how well it would be accepted if it is done with two conductor "duplex" cable.
For an electric water heater it might be possible to power each heater element from a separate breaker as an acceptable alternative. BUT it will require changing connections inside the heater. That is simple but not obvious how it is done.
I believe each wire must have a separate breaker, but they should be ganged so that if one trips, it trips the other.

If you put both on the same breaker, then if one of the wires breaks or otherwise becomes disconnected, you have a wire conducting far more than it is rated for, but within the limits of the breaker supposedly protecting it.
 

WBahn

Joined Mar 31, 2012
30,234
Hi.
Can two paralleled AWG#14 'romex' wires be installed instead of one AWG#10 'romex' to feed a water heater or an electric stove from a 30 Ampere breaker ?
What is the AWG# equivalent paralleling two AWG#12; or two AWG#14 ?
If you are in a position to install two wires in parallel, why aren't you in a position to install the proper gauge wire in the first place?

If it's just because that's what you have on hand, I don't consider that a very good reason.
 

nsaspook

Joined Aug 27, 2009
13,418
If you are in a position to install two wires in parallel, why aren't you in a position to install the proper gauge wire in the first place?

If it's just because that's what you have on hand, I don't consider that a very good reason.
There are good reasons for that as it depends on the circumstances. In a house, no way IMO but in industry, where you might have thousand foot rolls of X gauge and none of Y gauge , it can be a good choice to use what you've got if it meets code.

We been in that "that's what you have on hand" on a ship a few times. We once moved a very big AC unit (salt water condenser cooling that we took apart on the other side of the ship and reassembled inside) to our transmitter room because equipment was over-heating in the IO near the Persian gulf. The electricians ran double cables from the nearest main ships power terminal and ganged breakers for the AC electrical feed.
 
Last edited:

MisterBill2

Joined Jan 23, 2018
18,934
If you are in a position to install two wires in parallel, why aren't you in a position to install the proper gauge wire in the first place?

If it's just because that's what you have on hand, I don't consider that a very good reason.
The current price for copper wire is above three times what I paid not that long ago. PLUS some price gouging is also going on. My suggestion will not work for a stove, but for a water heater separating the 1500 watt elements to separate feed circuits can work and be legal and safe. Splitting a stove load is more difficult.
And dual breakers cost a lot more.
 

BobTPH

Joined Jun 5, 2013
9,120
In a typical US distribution panel, adjacent breakers are on opposite phases, so the typical ganged breaker (designed for 220V circuits) would not work unless the panel is modified. Can you get a ganged breaker that skips one slot?
 

MisterBill2

Joined Jan 23, 2018
18,934
In a typical US distribution panel, adjacent breakers are on opposite phases, so the typical ganged breaker (designed for 220V circuits) would not work unless the panel is modified. Can you get a ganged breaker that skips one slot?
I have not come across such a ganged breaker, except for three phase breakers that are normally only used in three phase panels. Those breakers are rather expensive.
 
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