Tankless water heater?
#21
(04-13-2017, 11:31 AM)tvguy Wrote:
(04-12-2017, 10:51 PM)chuck white Wrote:
(04-12-2017, 01:57 PM)tvguy Wrote:
(04-12-2017, 01:04 PM)chuck white Wrote:
(04-12-2017, 12:21 PM)tvguy Wrote:  The one I would need would require two 40 amp circuits. # 8 wire is good for 40 amps but unless the code has changed if you run a multi wire cable is has to be #6 wire times two.
If your service to your home is only a 100 amp system you would have to have an entire service change, probably 3000 bucks or so.

Look what you are saving per year below versus the cost of installation and do the math Smiling



 The U.S. Department of Energy estimates gas-fired tankless heaters save an average of $108 in energy costs per year over their traditional tank counterparts, while electric tankless heaters save $44 per year. ... Rewiring your house can easily add as much as $5,000 to the cost of installing a tankless water heater.May 28, 2009


? why #6 wire, is that for a Romex style?
Yes. You have to up the wire size when the wire is in a muti wire cable , AKA romex. But if you use conduit or flex you can pulls # 8 wire and put it on a 40 amp breaker.
I always thought it was a stupid rule.

I have used 12 AWG romex on 20 amp breakers,
and 10 Awg on 30 amps, was that wrong ?
That's correct.  

I don't remember exactly why but I know it used to be OK to run # 8 wire for a range and put it on a 50 amp breaker but you couldn't do the same for a hot tub. Maybe it's in the Oregon specialty code.

Maybe if you called the hot tub a water heater you could get by with it. Big Grin

I use the same rule of thumb, dropped two AWG for a 10 amp increase, So, 8 AWG was for 40 amps and 6 AWG was 50 amps.

But there is something I recently learned, about using a smaller AWG wire, if it's an internal wire to a sub panel that is connected to the main panel.
I haven't located the exact rule, but you can get by with short wires that are enclosed.
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#22
(04-13-2017, 01:05 PM)chuck white Wrote:
(04-13-2017, 11:31 AM)tvguy Wrote:
(04-12-2017, 10:51 PM)chuck white Wrote:
(04-12-2017, 01:57 PM)tvguy Wrote:
(04-12-2017, 01:04 PM)chuck white Wrote: ? why #6 wire, is that for a Romex style?
Yes. You have to up the wire size when the wire is in a muti wire cable , AKA romex. But if you use conduit or flex you can pulls # 8 wire and put it on a 40 amp breaker.
I always thought it was a stupid rule.

I have used 12 AWG romex on 20 amp breakers,
and 10 Awg on 30 amps, was that wrong ?
That's correct.  

I don't remember exactly why but I know it used to be OK to run # 8 wire for a range and put it on a 50 amp breaker but you couldn't do the same for a hot tub. Maybe it's in the Oregon specialty code.

Maybe if you called the hot tub a water heater you could get by with it. Big Grin

I use the same rule of thumb, dropped two AWG for a 10 amp increase, So, 8 AWG was for 40 amps and 6 AWG was 50 amps.

But there is something I recently learned, about using a smaller AWG wire, if it's an internal wire to a sub panel that is connected to the main panel.
I haven't located the exact rule, but you can get by with short wires that are enclosed.

It gets extremely complicated. The ampacity of the wire depends on the type on insulation and the temperature ratings.
Also the device the wires are terminated on matter. For instance in some cases you can use a smaller wire size IF your over current protection is fuses rather than circuit breakers.
Reply
#23
(04-13-2017, 01:12 PM)tvguy Wrote:
(04-13-2017, 01:05 PM)chuck white Wrote:
(04-13-2017, 11:31 AM)tvguy Wrote:
(04-12-2017, 10:51 PM)chuck white Wrote:
(04-12-2017, 01:57 PM)tvguy Wrote: Yes. You have to up the wire size when the wire is in a muti wire cable , AKA romex. But if you use conduit or flex you can pulls # 8 wire and put it on a 40 amp breaker.
I always thought it was a stupid rule.

I have used 12 AWG romex on 20 amp breakers,
and 10 Awg on 30 amps, was that wrong ?
That's correct.  

I don't remember exactly why but I know it used to be OK to run # 8 wire for a range and put it on a 50 amp breaker but you couldn't do the same for a hot tub. Maybe it's in the Oregon specialty code.

Maybe if you called the hot tub a water heater you could get by with it. Big Grin

I use the same rule of thumb, dropped two AWG for a 10 amp increase, So, 8 AWG was for 40 amps and 6 AWG was 50 amps.

But there is something I recently learned, about using a smaller AWG wire, if it's an internal wire to a sub panel that is connected to the main panel.
I haven't located the exact rule, but you can get by with short wires that are enclosed.

It gets extremely complicated. The ampacity of the wire depends on the type on insulation and the temperature ratings.
Also the device the wires are terminated on matter. For instance in some cases you can use a smaller wire size IF your over current protection is fuses rather than circuit breakers.

My house uses to be on fuses, but the insurances wanted breakers, so I installed them years ago. You just remind me, the oven  still has a fuse between the breaker and the oven. I installed the new breaker box next to the old fuse box The wires from the oven made it up to the fuse, so that was a good place to splice in from the breaker.
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#24
(04-13-2017, 10:46 PM)chuck white Wrote:
(04-13-2017, 01:12 PM)tvguy Wrote:
(04-13-2017, 01:05 PM)chuck white Wrote:
(04-13-2017, 11:31 AM)tvguy Wrote:
(04-12-2017, 10:51 PM)chuck white Wrote: I have used 12 AWG romex on 20 amp breakers,
and 10 Awg on 30 amps, was that wrong ?
That's correct.  

I don't remember exactly why but I know it used to be OK to run # 8 wire for a range and put it on a 50 amp breaker but you couldn't do the same for a hot tub. Maybe it's in the Oregon specialty code.

Maybe if you called the hot tub a water heater you could get by with it. Big Grin

I use the same rule of thumb, dropped two AWG for a 10 amp increase, So, 8 AWG was for 40 amps and 6 AWG was 50 amps.

But there is something I recently learned, about using a smaller AWG wire, if it's an internal wire to a sub panel that is connected to the main panel.
I haven't located the exact rule, but you can get by with short wires that are enclosed.

It gets extremely complicated. The ampacity of the wire depends on the type on insulation and the temperature ratings.
Also the device the wires are terminated on matter. For instance in some cases you can use a smaller wire size IF your over current protection is fuses rather than circuit breakers.

My house uses to be on fuses, but the insurances wanted breakers, so I installed them years ago. You just remind me, the oven  still has a fuse between the breaker and the oven. I installed the new breaker box next to the old fuse box The wires from the oven made it up to the fuse, so that was a good place to splice in from the breaker.

I one wired some three phase equipment at a beer distribution place. I used a fused disconnect we had available and because it was already fed from a circuit breaker I didn't need fuses. So I cut some copper pipe and put it in where the fuses went.
And I wrote on them 4000 amps LOL.
A couple of years later one of our guys saw it. took a picture and brought it in to the shop to show EVERYONE Razz
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