What AWG for 7.5kw - 36amp heater?
 

Hello,

I would like to install a Dayton, ceiling mounted, electric heater in
my 2 1/2 car garage/woodshop.

The heater runs on 208 or 240volts - 36.5amps - 7,500watts and puts out
25,600BTUs.

What size awg wire would I need for this heater?

The wire will run from the main panel and hard wired to the heater.

Any advice will be greatly appreciated!!!

Thanks,
Roy

What AWG for 7.5kw - 36amp heater?
 

If you're running cable, you'll need 6\2g or if you're running conduit and
THHN you can use #8


"Roy Fek" wrote in message
ups.com...
Hello,

I would like to install a Dayton, ceiling mounted, electric heater in
my 2 1/2 car garage/woodshop.

The heater runs on 208 or 240volts - 36.5amps - 7,500watts and puts out
25,600BTUs.

What size awg wire would I need for this heater?

The wire will run from the main panel and hard wired to the heater.

Any advice will be greatly appreciated!!!

Thanks,
Roy

What AWG for 7.5kw - 36amp heater?
 

In article , RBM wrote:
If you're running cable, you'll need 6\2g or if you're running conduit and
THHN you can use #8


"Roy Fek" wrote in message
oups.com...
Hello,

I would like to install a Dayton, ceiling mounted, electric heater in
my 2 1/2 car garage/woodshop.

The heater runs on 208 or 240volts - 36.5amps - 7,500watts and puts out
25,600BTUs.

What size awg wire would I need for this heater?

The wire will run from the main panel and hard wired to the heater.

As I remember, 10 AWG is good for 30 amps with me remembering a bit of
talk for 25 in some cases, 12 is good for 20 amps, 14 is good for 15
amps...

Sounds to me that 8 AWG is the minimum size for likely next step up of
40 amps...

Checking Google...

http://amasci.com/tesla/microtc.html despite unlikely URL shows a page
that appears to be one of a local government website showing wire size
rules that appear to me to be usual/nationwide-USA. First paragraph shows
intent to comply with NEC.

The above page indicates 8 AWG sufficient for 40 amps.

However, I remember from some recent past reference to some NEC tidbit
that a continuous load should not have current draw exceed 80% of circuit
ampacity. I consider a heater to be considered more a continuous load
than an intermittent one. 36.5 amps exceeds 80% of 40 amps but is less
than 80% of next step up of 50 amps, which requires 6 AWG wire according
to the above page in the likely event that the above heater gets to be
considered a continuous load.

--
- Don Klipstein )

What AWG for 7.5kw - 36amp heater?
 

Roy Fek wrote:
Hello,

I would like to install a Dayton, ceiling mounted, electric heater in
my 2 1/2 car garage/woodshop.

The heater runs on 208 or 240volts - 36.5amps - 7,500watts and puts out
25,600BTUs.

What size awg wire would I need for this heater?

The wire will run from the main panel and hard wired to the heater.

It 'sounds' like #8AWG.
But?
Wiring distance is not given. Is it a separate free standing
garage/woodshop building? Or attached to house?
Questions?
Voltage drop/wiring distance?
Is/will there be other electrical wiring to that woodshop/garage area?
If so is it a separate service or are outlets, garage lights, shop
tools etc. also wired to other fuses/circuit breakers on the same main
panel? Cos there are some rules about having 'mixed' services in same
building?

What AWG for 7.5kw - 36amp heater?
 

A #8 NM cable is good for 40 amps, which is not large enough for a heater
that draws 36.5 amps



"Don Klipstein" wrote in message
...
In article , RBM wrote:
If you're running cable, you'll need 6\2g or if you're running conduit and
THHN you can use #8


"Roy Fek" wrote in message
roups.com...
Hello,

I would like to install a Dayton, ceiling mounted, electric heater in
my 2 1/2 car garage/woodshop.

The heater runs on 208 or 240volts - 36.5amps - 7,500watts and puts out
25,600BTUs.

What size awg wire would I need for this heater?

The wire will run from the main panel and hard wired to the heater.

As I remember, 10 AWG is good for 30 amps with me remembering a bit of
talk for 25 in some cases, 12 is good for 20 amps, 14 is good for 15
amps...

Sounds to me that 8 AWG is the minimum size for likely next step up of
40 amps...

Checking Google...

http://amasci.com/tesla/microtc.html despite unlikely URL shows a page
that appears to be one of a local government website showing wire size
rules that appear to me to be usual/nationwide-USA. First paragraph shows
intent to comply with NEC.

The above page indicates 8 AWG sufficient for 40 amps.

However, I remember from some recent past reference to some NEC tidbit
that a continuous load should not have current draw exceed 80% of circuit
ampacity. I consider a heater to be considered more a continuous load
than an intermittent one. 36.5 amps exceeds 80% of 40 amps but is less
than 80% of next step up of 50 amps, which requires 6 AWG wire according
to the above page in the likely event that the above heater gets to be
considered a continuous load.

--
- Don Klipstein )

What AWG for 7.5kw - 36amp heater?
 

What neck of the woods do you live in? Depending on you elec cost, that
sounds like a lot of amps and $$$. Have you considered gas or oil
heat? Is it feasible for your garage?

What AWG for 7.5kw - 36amp heater?
 

Mikepier wrote:
What neck of the woods do you live in? Depending on you elec cost, that
sounds like a lot of amps and $$$. Have you considered gas or oil
heat? Is it feasible for your garage?


My workshop is an attached garage and I live in the Seattle area so
winters aren't all that bad here. Although, you wouldn't know that by
looking outside today! 6 inches of snow and and a low of 18* tonight,
this RARELY happens.

The distance from the main panel to the heater would be approx. 20-25
feet.
I have room in my 200 amp panel for a 50amp 2 pole circuit to power the
unit. This panel also powers the other lights/outlets in the garage as
well as the rest of the house.

I got an estimate of $3,000 to have a Reznor type natural gas heater
install, this includes the unit and piping gas to the garage. Since the
gas meter is on the opposite corner of the house, they would have to
pipe it over to the garage.

I talk to my gas/electric utility company about costs and this is what
they said. For $100 in natural gas, I would spend $156 in electricity
for the same amount of "power". So I realize that gas is a cheaper
fuel.
Electricity costs me 8.6 cents per kilowatt hour. So to run a 7.5kw
heater will cost me $0.65 an hour to run. I'll run the heater 1-2 hours
per day, which maybe 4-5 times a week. This is how much I run my
23,000btu kerosene heater now. So in a month I'll pay between $13-26 a
month for electric heat.
The unit it self will cost me approx. $500 and I will hang the heater
and run the wire myself. I just need a qualified electrician to hook
the wire to the panel, maybe $100.

So I can spend approx. $600 to have the electric heater installed or
$3000 to go with gas.
That's why I considering electric heat. If I were in the shop all the
time, say 40 hours/week, then I would go with gas.

Roy

What AWG for 7.5kw - 36amp heater?
 

"Roy Fek" wrote in message

Electricity costs me 8.6 cents per kilowatt hour. So to run a 7.5kw
heater will cost me $0.65 an hour to run. I'll run the heater 1-2 hours
per day, which maybe 4-5 times a week. This is how much I run my
23,000btu kerosene heater now. So in a month I'll pay between $13-26 a
month for electric heat.

Your electric is about half what I'm paying in CT. In your case, the
payback for gas is much too long to consider it.

What AWG for 7.5kw - 36amp heater?
 

RBM (remove this) wrote:

A #8 NM cable is good for 40 amps, which is not large enough for a heater
that draws 36.5 amps

I believe the OP said that the heater was 208/240 volt. Most
residences do not have 208 volt service. For 7.5 kW, the 36.5 amp draw
should be for a 208 volt service. For a 240 volt service, 31.2 amps.
125% of 31.2 = 39 amps. He could use a 40 amp circuit in that case,
assuming no motor. Either way, I would strongly recommend using copper
wire, in fact, his local electric code may require copper wire to
heating units. A separate disconnect should not be required since the
panelboard is in sight of the heating unit.

What AWG for 7.5kw - 36amp heater?
 

Your right, I just looked at his amperage draw and assumed it was for 240
volt


"volts500" wrote in message
oups.com...
RBM (remove this) wrote:

A #8 NM cable is good for 40 amps, which is not large enough for a heater
that draws 36.5 amps

I believe the OP said that the heater was 208/240 volt. Most
residences do not have 208 volt service. For 7.5 kW, the 36.5 amp draw
should be for a 208 volt service. For a 240 volt service, 31.2 amps.
125% of 31.2 = 39 amps. He could use a 40 amp circuit in that case,
assuming no motor. Either way, I would strongly recommend using copper
wire, in fact, his local electric code may require copper wire to
heating units. A separate disconnect should not be required since the
panelboard is in sight of the heating unit.