[Amps] 240V Outlet

Paul Christensen w9ac at arrl.net
Sun Aug 9 12:12:36 PDT 2009

> Our electrician recommended that we pull  both phases, neutral and
> ground to each location, regardless if the device needed a neutral.
> This would allow flexibility should we install new equipment.

Excellent advice.

>    * To oversize the wire by at least one gauge size (on a 20 amp
>      circuit, use #10 wire instead of the #12) to address potential
>      voltage drop issues.

It's been a while since I've reviewed that section of the NEC, but I suspect 
over-sizing the wire size is fine, but I would never oversize the breaker 
current rating, nor would I over-size on the receptacle and plug.  In the 
latter case, I've seen instances where a 20-amp 120VAC receptacle is used, 
but the conductors are sized at #14 AWG.   Looking at the receptacle gives 
the incorrect impression that the branch is rated for 20-amps, when in fact 
it's only rated at 15-amps.  The breaker rating, wire size, receptacle and 
plug should all match the intended current-carrying capacity.

>    * Use twist-lock or IEC 309 pin and sleeves, instead of straight
>      blade connectors.

Love that idea too.  I use 4-wire, 30-amp Hubbell or Leviton Twist-Lock 
types on all amps and 240VAC service to the shack.  Conductor size is #10 
AWG to match that of the 30-amp breaker and 30-amp Twist-Lock receptacle. 
If I were running smaller amps, I would also consider running companion 
4-wire, 20-amp service to better match the amplifier's current draw with 
that of the electrical distribution system.

Paul, W9AC 

More information about the Amps mailing list