40 Amp Breaker For A Water Heater

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So, are you looking for information related to 40 Amp breaker for a water heater?

Well, in this post, I would be walking you through some of the frequently asked questions related to 40 Amp and water heater in order to help you make an informed buying decision.

Moreover, I’ll also try to cover questions related to the topic so that you can have a better understanding of the 40 amp breaker.

So, without any further ado, let’s begin…

Can I replace a 30A breaker with a 40A breaker for a new water heater?

To be honest, one of the most frequently asked questions by our clients whenever they upgrade to a new tankless water heater from a tank-styled counterpart is whether they can replace a 30A breaker with a 40A breaker or NOT.

Trust me, today, I’m gonna end this age-old debate so that henceforth you can do the needful without any confusion.

To be honest, it’s isn’t possible to replace a 30A breaker with a 40A breaker in general, and in case of doing such a thing, you may expose yourself and your family to unprecedented danger including fire.

In layman’s terms, 10 gauge wire requires at most a 30A breaker, whereas 8 gauge requires at most a 40A breaker.

It’s possible the builder ran #8 wire to the water heater, in a bit of forward-thinking future-proofing, but it’s more likely they only ran #10, and thus stuck a 30A breaker on.

In fact, you can’t put a 40A breaker on the #10 wire and as said earlier refrain from even trying to do such a thing because it may lead to a fire.

On the other hand, if you’re sure that there is (at least) #8 wire all the way from the breaker to the water heater then your works become easy as in this case, you can replace the 30A with a 40A breaker.

But, before expediting the process, you need to make sure that the size of the wire throughout the circuit is the same.

Never try to replace a 30A breaker with a 40A counterpart in case the size of wire throughout the circuit isn’t uniform.

Again, I’m reiterating don’t even dare to commit the mistake of under-sizing your tankless heater as it impacts your home adversely.

If you’re a first-time buyer of an electric tankless water heater, then you might not be aware of the fact that these on-demand heaters need a huge amount of energy, and failing to provide them the required energy can lead to their underperformance.

The problem with a 40A (8.8kW) device is that it provides a low flow for the whole house and so even filling a tub will consume a lot of time.

Well, a 30A breker protects your system by preventing excessive current from flowing into the system.

But, that isn’t the case with a 40A breaker as it raises the ceiling on the allowed current.

In simple words, if you’ve installed a 40A breaker than it will lead to excessive current flowing through the wiring than it can accommodate resulting into malfunctioning and in the worst case, even fire may breakout.

However, if the wire is in open air and NOT enclosed in the wall with insulation or bundled with other wires then the scenario is completely different.

In such scenario, its temperature would be within safe limits at 40A with 10 AWG copper.

But, at the same time, if someone comes and put insulation around the wire in the open space then definitely, it would be nightmare for you.

Not only that but also you would be wasting more energy by creating extra heat in the wire.

Well, the US electrical code is kind of strange. It allows you to put a 60A breaker (4 times the heat generated in the wire) on a normally 30A 10 AWG circuit if it is a dedicated welder circuit, since welders have limited duty cycles.

The primary purpose of any breaker is to protect the cable from short circuits and overheating to prevent any unprecedented events including fire breakout.

Many of the first-time buyers aren’t aware of the fact that the rating of a cable isn’t based only on its size or gauge but also on the individual installation conditions along each individual part of its run.

Cables installed through batts or insulation on a part of the run have a lower current rating for the same gauge than cables installed in free air or, underground or possibly, in conduit.

Do you know that cables that are installed through roof spaces often end up having a lower current rating than the ones that are installed a house?

The reason being higher ambient temperature in a roof.

Moreover, the total length of the cable run is also a factor, longer runs can require you to go one or more gauges heavier (due to VD/A/ft) but this does not increase the current carrying capacity at all in that case.

What are 40 amp breakers used for?

So, now you know that you can’t use a 40A breaker to serve water heaters and electric dryers so you might be inquisitive to know where you can use it, right?

Well, a 40 amp breaker could be a PERFECT choice for electric ranges and trust me, it will NEVER offend you and will definitely match up to your expectation.

Which gauge wiring is used for a 40A breaker?

Both 8-gauge and 6-gauge wiring can be used for a 40A breaker.

Wrapping Up | 40 Amp Breaker For A Water Heater

First and foremost, I would like to thank you for being with us till the end.

I hope your quest for information related to 40 Amp breaker for a water heater would’ve ended by now.

Secondly, I would like to bring to your notice that I along with my core team have put loads and loads of efforts in coming up with this idiosyncratic superlative piece of information.

And, in case, you liked our effort then please do share this piece of information with the like-minded people and the ones who are in need for it.

After all, sharing is caring, isn’t it?

Cutting long-story-short, the answer to can I replace a 30A breaker with a 40A breaker for a new water heater is a BIG NO…

And, I request you to NEVER try such things as it could be quite dangerous at times.

That’s all, as of now:):)

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