What size circuit breaker and type for my system?

I recently had a new latest spec consumer unit fitted (groan) and I often have problems getting my system powered up. Breaker is a type B at 16 amps.
My system comprises
CDS2 with PSU, Snaxo with Supercap, 552 and 555 with their PSU’s plus four NAP250’s
I can usually get most on if I wait 30 seconds or so between each switch on but it invariably fails on the last one or two units. I have tried different units to no avail
Do I try a bigger type B circuit breaker or a same size type C?
Any help appreciated

The 16 amp breaker should be sized to the cable and as such cannot be increased.
you could try a 16 amp type ‘C’.

It depends where you live, EU & UK domestic power systems are different.

If you are EU, the power distribtion system has radial circuits & 16amp RCCB are normal/typical.
If you are UK, its normaly a ring main circuit(s) & 32 amp is the normal rating. However if the probelm circuit is a radial, then 16 amp is correct.

Whatever, a Type C RCCB is more suitable to handle the inrush currents of the Naim transformers, and whatever the power system (as above), I would go for a Type C.

You should, in any case, power up each box one at a time, in the correct order, leaving a short time in between each one.
Tripping when you switch on is nonetheless common with the big toroidal transformers Naim use. A type C breaker should take care of that.
The size and type of breaker required depends on many variables including the cable size and length, the route it takes, as well as the current drawn by the appliences. I would say at least 32A but a qualified electrician should be able to select a suitable size. Any changes will need to conform to current regs, which may require RCD protection.

It would help to know were you are due to different regulations

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Thanks all for the advice. I am in the UK, the cable is well oversized deliberately but it sounds like a 16amp type C is what to go for so I will go get and report back

I normally put the amps and snaxo power on first one by one waiting a few seconds between, then the PSU for the streamer then the PSU for the pre amp. Does that sound right to you?

I always put source first units on especially pre amp etc.
That way when the power amps go on they are always under control.
Always been my startup.

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Hi, You should power on your sources first, then your preamp, then your SNAXO power supply and finally your amps.

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I follow the source first rule for switch on (streamer tuner or their PSU) then the pre-amp stage (or PSU), then finally the power amp stage.

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Definitely source first, then preamp, when switching on. Do the reverse when switching off. Also good practice to turn volume right down and or engage the mute button to reduce the chance of nasty surprises.

It’s all in the FAQ;

Because the breaker is there to protect the cable from overheating, not your attached gear, critical to breaker amperage rating is the cable: Conductor size, construction (T&E with PVC insulation most common in Britain), and where if runs e.g. clipped to a solid wall otherwise exposed, through conduit, or through or under insulation, and maximum ambient temperature where it runs. If you have modern cable of the 10mm2 size cable popularly used for dedicated system wiring, and not running anywhere with a temperature above about 30C, then given any normal construction run I don’t think there is any situation where it would not be quite safe with a 32A breaker - but of course a competent qualified electrician should advise, with full awareness of the cable run, before making such a change. That said, given that the likely cause of tripping is the equipment inrush current, use of a class C breaker which is specifically for that sort of scenario would likely be the best solution.

Never has issues with a B Type breaker even with the infamous XPS. :slightly_smiling_face:

As an others have advised Naim state to switch on the power amps last.


And that applies to any system, whether or not Naim. Power amps on last and off first. Anything else may risk speaker damage if the act of switching on/off induces a pulse that is amplified by the power amp.

Update, I fitted a 16a Type C and problem solved. Initial surge is a bit hefty I guess.

Thanks all for your advice, also on turning on and off, useful reminder

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