Amp and preamp on same outlet?

See page #5

Full Power Balanced
X Series Power Amplifiers

AC POWER GUIDELINES
The Full Power Balanced 300cx and 350Mcx
amplifiers need to be operated from a dedicated
AC power line rated at a minimum of 15
amps. The Full Power Balanced 700cx,
750Mcx, 400cx, and 450Mcx amplifiers need to
be operated from a dedicated AC power line
rated at a minimum of 20 amps.
Please contact your authorized Krell dealer, distributor,
or Krell before using any devices
designed to alter or stabilize the AC power for
Full Power Balanced amplifiers.

Note the word [minimum] used for the "750Mcx, 400cx, and 450Mcx amplifiers need to be operated from a dedicated AC power line rated at a minimum of 20 amps."

If the equipment is manufactured for use in the USA with the intent of using a power cord with a NEMA 5-20P 125V 20 amp plug then the max branch circuit ampacity rating is 20 amps. Period! The minimum branch circuit ampacity rating because of the NEMA 5-20P plug is 20 amps. Period!

Minimum wire size #12AWG copper.
Branch circuit breaker size, 20 amp. Period!
Receptacle, if the Krell power cord plug is a NEMA 5-20P plug then a NEMA 5-20R 125V 20 amp receptacle for the plug to fit it is required.

All the above are NEC Code minimum electrical safety standard requirements.

Krell can spec #10 AWG copper wire, which I would recommend. For long branch circuit runs maybe even #8 AWG Cu.
They can spec an HM, High Magnetic, 20 amp breaker must be used to help prevent nuisance breaker tripping.
They should spec that only power cords that has a NEMA 5-20P plug can be used with a minimum cord conductor wire size of #10AWG.
They can spec only a NEMA 5-20R 125V 20 amp heavy duty commercial/industrial rated receptacle be used.
The bigger wire and heavy duty receptacle will help reduce voltage sag on the branch circuit wiring, receptacle contacts to plug blades, and power cord wire right up to that 20 amp IEC inlet connector mounted on the back of the unit caused by the Krell amp's dynamic power connected load.

They cannot spec a 30 amp circuit breaker be used on a 20 amp branch though. You will notice in the owner manual a 30 amp branch circuit was not mentioned. Everybody reading this thread by now should know the reason why.

.

Edit for previous first post dated 03-03-15: Jea48

NEC Code
210.21 (B)(3) Receptacle Rating.
Where connected to a branch circuit supplying two or more receptacles or outlets, receptacles ratings shall conform to the values listed in table 210.21(B)(3), ...........

NEC Table 210.21(B)(3) Receptacle Ratings for Various Size Circuits.

Circuit Rating ..... Receptacle Rating
(Amperes) .............. (Amperes)
15 ............................ 15
20 ....................... 15 or 20
30 ............................ 30

Minimum wire size #10awg. Breaker size 30 amp.

*No exception given for Krell Inc.

>>>>>>>>>>>>>>>>>>>>>>>

Strike,

Minimum wire size #10awg. Breaker size 30 amp.

and replace with,

The branch circuit breaker size determines the size of the branch circuit.

If the branch circuit breaker is 30 amp then the minimum wire size must be #10 AWG. It can be bigger but it cannot not smaller.
The receptacle must be a NEMA 125V 30 amp rated receptacle. It cannot be bigger, it cannot be smaller, it can only be a NEMA 30 amp rated receptacle.
.

Jea48- Save the bandwidth. He's not listening. Or he can't read. Or he believes that the building and electrical code writing authorities are conspiring w Bose to make us listen to inferior sound ;-)

Jim (Jea48), it seems that John (Jmcgrogan2) was right. Fool Hardy has no interest in learning to sing and you are getting frustrated trying to make it happen. I remember you trying to tell him the same thing in another thread a while back. Hopefully, others reading this thread will follow your advice, which as usual, is excellent. It would be a shame for anyone to burn their house down for the sake of trying to make their system sound better. One of the things I remember from the other thread is that after all of those "upgrades", he was still tripping breakers and wasn't sure why. YIKES!

Hi Jim, sorry, I just got back to this thread, yes, I have been listening, I do have a 10/3 romex connected to a furutech GTX-D Rhodium for my amp, yes, The Krell 700cx amp comes with a captive power cord that says 600 volts rating on it, Jim, I have said over and over, my amp is NOT useing all 30 amps, it simply spikes over 20 amps, all I am saying Jim-Jea48, My krell 700cx runs cooler, more dynamic, bigger sound stage, more or less, effortless useing a 30 amp single pole breaker versus a single pole 20 amp breaker, I was shocked after 20hrs of burn-in of the breaker at the difference this made, Damn Jim, this is the best cheap tweak ever I have done, more than cost effective, I do not know why or how Jim, But I assure you, the 20 amp breaker in my opinon, was chocking my amp!, Thankyou jim for all the post you have done, I really don't have an explaination, I am just telling you that this works, no problems, and was worth doing, and that I know many members of audiogon that did the same here with their Krell amps, I was afraid to do it Jim, Chris Vanhas of vh-audio sold me the furutech GTX-D R with the understanding that it would not heat up or damge the outlet with a 30 amp breaker because of how well it is built, as it turns out, he was correct, not even warm!, I have checked this outlet over and over, the wires going to it, if any smell was coming from it, for heat, nothing, the wpo-wall power outlet is cold all the time with NO issues, thanks jim.