Breakers for KPA1500?

Neither Tony or I suggested making a 120v circuit from the two wire 240v
line using the ground as the neutral.  Yes you can run three conductor
Romex and have a 120v and 240v outlet but I do not see this as a good plan
as it could easily exceed 20 amps on one leg. Upgrading to higher amperage
circuit and you'll exceed the amperage rating for a standard 120v outlet.
Two separate circuits are much easier to manage.

John KK9A


Don Wilhelm W3FPR wrote:

Tony,

While it is possible and safe to use only two wires plug safety ground
(Green Wire Ground) for a 240 volt receptacle or 240 volt only device
(in-home air conditioner, dryer, etc), it is quite unsafe to split off
for a 120 volt supply using one hot and ground - in that case (such as a
range that has a 120 volt outlet on it or a 120 volt fan) you MUST run 3
conductors plus ground.
The ground wire should never carry current.
An inspector would never approve it, and if you value your insurance
coverage, don't try it - it will be found after the fire!

73,
Don W3FPR

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[Mark Goldberg]

Let's put this in monetary terms. 100 ft of 12/2 with ground is $56 at Home
Depot. 100 ft of 10/3 with ground is $138.

If you pay an electrician to do the work, the difference won't be 10% of
the bill.

If you do it yourself, following code and getting it signed off by an
electrician and inspected of course so your insurance won't deny coverage,
and you value your time, and there is a chance you may want extra 120 V in
the future, it will save hours of replacing it later.

I would go with the 10/3 with ground, but that's just me.

When you sell your house and the next owner wants to put something else
there, you may get more for the property. For example, the previous owner
of our house installed a 20A RV power outlet. And yes, it came from one
side of a 20A 240V feed with a neutral and ground. That was worth hundreds
more to us.

I would still put in 20A breakers. They protect the wires and if all you
need is 20A for the load, it seems sensible to be more protective. I have
heard of inspectors seeing 20A breakers and AWG10 wire and questioning it,
but it seems you could explain it was done for an extra safety factor, etc.
Breakers are quick to change.

Good luck with whatever you do.

73,

Mark
W7MLG
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[Jim Brown-10]

On 7/10/2018 9:13 AM, [hidden email] wrote:
> Yes you can run three conductor
> Romex and have a 120v and 240v outlet but I do not see this as a good plan
> as it could easily exceed 20 amps on one leg. Upgrading to higher amperage
> circuit and you'll exceed the amperage rating for a standard 120v outlet.
> Two separate circuits are much easier to manage.

It's hard to imagine how 20A on a 240V circuit split to 120V outlets
(with neutral) could be exceeded in a single operator ham station
running legal power, and powering only ham gear from that circuit. Let's
say that the power amp is drawing 15A keydown. That's 3.6kW, and you
still have 5A at 120V on each of the two legs. Now, let's say that you
have an Astron 14.4V supply running on one of those outlets powering a
tranceiver, even two or three tranceivers, only one of them TX at a
time. I find it hard to believe that the Astron draws more than 3A,
probably less. Add an old big iron computer to the other leg, maybe 1A
on that leg. Indeed, a second power amp could be running off that
circuit as long as only one is in TX mode at a time!

73, Jim K9YC

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