Ummm, not exactly following your description but ... NA electrical
codes require the two phase conductors [240V between them], after
passing through the breaker(s), to go directly to the equipment. The
center-tap of your distribution transformer secondary [neutral] is
bonded to earth ground at your service entrance. The earth ground
becomes the "green wire" [it may be uninsulated and thus the "copper"
wire] and should be bonded to the enclosure of the equipment. It's the
safety ground and that's all that should power a 240V equipment. Ugly
things can happen if the neutral gets involved or used as a ground.
If that's what you're describing, exactly, it's probably good. How long
a run from the outlet to the KPA500? I'd also make sure the outlet is
wired properly. If it's an old dryer plug, an electrician with a
license might be in order.
For 120V, the neutral forms one side of the circuit, however the safety
ground [green wire] still should be bonded to the equipment enclosure.
Under no circumstances should you connect the green wire to the neutral
ANYWHERE but the bond in your service entrance.
73,
Fred K6DGW
Sparks NV
Washoe County DM09dn
On 7/11/2016 1:42 PM, Matt Murphy wrote:
Hello, I am thinking of connecting my KPA500 to a 240V outlet that is close
to the shack that has a NEMA 10-30 receptacle. I'm soliciting advice on
how to proceed.
As background, I am looking into this because the lights dim a bit when the
amp is keyed down. It's a bit distracting and while I don't think the
circuit is actually overloaded, it's definitely close to the limit.
I was thinking of making a cable by modifying an IEC power cord (with C13
connector) by connecting the two wires to the two hots of a NEMA 10-30
plug, and ignoring the neutral plug AND ignoring the ground wire in the IEC
power cord.
A few questions about this approach:
- Is it the correct way to wire the connectors together?
- Is it dangerous in any way?
- Is there anything that can be done to reduce/mitigate the danger (if any)
other than having an electrician install a currently-up-to-code 240V
circuit in the shack?
- With respect to safety, assuming it is safe for the KPA500 would it be
safe to run other amplifiers that require 240V? How would I determine
this? It seems that clothes dryers that are connected via a NEMA 10-30
connector typically have the neutral pin connected to the chassis.
Based on my research, the NEMA 10-30 connector was used widely before it
was declared not up to code for new installations in 1996. Since many homes
were built prior to 1996, I would imagine that others on the reflector
might have encountered this sort of issue when dealing with 240V in the
shack.
Advice appreciated.
73,
Matt NQ6N
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