Just leave it powered up……as it was designed to be used?
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If you are in the U.K., a Type C breaker is what you want. And once on, don’t turn the 250 off, other than for going on holiday, if lightning is likely, or for the annual system clean and rebuild.
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Looking at the fuse it appears to be type B, so what’s the difference between a c and a B?
I don’t like leaving on when I’m away from home and besides Naim put the on off button on the front as opposed to the rear on previous Naim gear I’ve owned except the Nap140
It will be on now until Sunday evening and then off as I’ll be away.
I was more interested why it keeps tripping, faulty amp or breaker/fuse.
I suggest you ask Mr Google if you want a technical explanation. It’s all about inrush current or something like that. But get a Type C and it will almost certainly make the problem disappear. It’s what I use and it’s what most people on here, who have big power supplies, use.
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The difference is described here:
Type B devices are designed to trip at fault currents of 3-5 times rated current (In). For example a 10A device will trip at 30-50A.
Type C devices are designed to trip at 5-10 times In (50-100A for a 10A device).
(mainly about equipment fuses, but the part about the inrush current applies to the mains breaker similarly)
The equipment fuse is fine, I know as I swapped the spare fuse that’s located in the fuse holder at the back of the amplifier.
I recently had a new consumer unit installed and wonder why the sparky didn’t use a c fuse over a B fuse.
I understood that, my point was that the inrush current that can trip the equipment fuse can also trip the mains breaker if it’s of the fast-blowing kind. The concepts in the FAQ are still applicable and useful
Type B is more standard. Just get a C.
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Type C is used for more inductive loads such as transformers. As others have said, fit this type. This will fix the issue.
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Type B is standard for domestic uses and an electrician would fit them in pretty much any domestic installation. Type C would be more common for industrial use, but the high inrush current when you turn on a Naim box with those outsized toroidal transformers can be too much for a type B. Get it changed and I very much doubt you will ever trip it again.
Looks like C it is then, I’ll get the sparky to swap it over.
Thanks all.
That’s exactly what I had to do. The the 300, SC2 and current 145 & 200 could/would all trip it. It could take 30 mins to switch on the system if it had been off for a more than a few hours.
I wouldn’t have stood any chance trying to power up the 500 on the Type C.
Yes… anything with a very inductive reactive load such as a big motor or a largish efficient transformer will likely need a category C MCB …
In short the more inductive the load, the more it resists change so has a large initial surge current… as the load briefly resists being energised.
The other consideration of highly inductive loads is power factor and power factor correction… a poor power factor ratio can cause issues, add distortion harmonics into the mains and even cause higher electricity bills… I never got to the bottom of whether Naim power factor correct their larger transformer circuits.
I have also had this problem from time to time,
And it can happen with any of the power supplies as well as the power amp.
I got into the habit after switching off everything, of unplugging everything and then pressing
the power button on each of the power supplies while unplugged.
Tripping might also be a voltage issue. My NAP 300 worked fine off a 20A type B MCB for years, then one day it tripped at switch on, (I turn my system on and off every time I use it). After this It tripped the MCB 3 or 4 times that month. It was only then that I noticed that the ground floor ring circuit was on a 20A type B. I suspect the mains voltage has been raised a little by the utility Co. over time.
I had the MCB replaced with the correct 32A type B MCB and it hasn’t tripped it at all.
Years ago with an early 250, on swith on, the lights would dim for a few seconds.
Electrical installations and utility supplies to dwellings can vary, especially with older installations. Little is made of this in the HiFi world, and yet we babble on about tiny tweaks.
With regard to power distribution companies, I think the main thing that will affect SQ that you have control over is earthing setup… whether PME or TT.
TT is nearly always better for low noise mains… and I try and mention that when I can. In my experience hugely more relevant than having a dedicated radial in most domestic setups, in my opinion… especially with Naim setups where the earth ground is not decoupled.
I do wonder how many times when peeps say their system has sounded better or worse at a point in time that is down to them using PME distribution…
I can’t imagine most would know what type of installation they have!
It may say by their incoming fuse.
But the age of their house/supply will be a good start for those that don’t know for sure. Older supply or living in a rural area then more likely to have TT. New build always TNCS ( PME).