What’s up with Sonoff’'s directive to add 6A or 10A circuit protection to their devices? In most cases these are being installed on circuits that are wired with 14 gauge wire and 15A circuit breakers. That does not meet the specification of either 6A or 10A circuit protection (Sonoff says both 6A and 10A in their manuals).
Here are the statements verbatim from the Sonoff ZBMINIL2 Quick Guide and the ZBMINIL2 and MINIR4M User Manuals:
ZBMINIL2 Quick Guide V1.0 (still being shipped from ITEAD in December 2023) –
“To ensure the safety of your electrical installation, it’s essential either a Miniature Circuit Breaker (MCB) or Residual Current Operated Circuit Breaker (RCOCB) with an electrical rating of 6A has been installed before the ZBMINIL2.”
ZBMINIL2 Quick Guide V1.1 (2022-11-18) –
The above language has been completely omitted, but in the User Manual there is still (December 2023) a directive in the ZBMINIL2 User Manual to add 10A of circuit protection.
ZBMINIL2 User Manual V1.0 (from Sonoff website on 12/15/2023) –
Before installing the device, please install an air switch as the protective device (Air switch: 10A/250V).”
|Input| 100-240V AC 50/60Hz 6A Max
|Output| 100-240V AC 50/60Hz 6A Max
|Max. load| Resistive load: 6A Max LED:150W Max @100V, 300W Max @240V”
MINIR4 User Manual V1.0 (from Sonoff website on 12/15/2023) –
To ensure the safety of your electrical installation, it’s essential either a Miniature Circuit Breaker
(MCB) or a Residual Current Operated Circuit Breaker (RCBO) with an electrical rating of 10A
has been installed before the MINIR4M.”
|Rating| 100-240V~ 50/60Hz 10A Max Resistive Load μ
|Max. power| 2400W@240V”
So, which is it that is required?
Is it a 6A Miniature Circuit Breaker (MCB)?
Is it a 6A Residual Current Operated Circuit Breaker (RCOCB)?
Or is it a 10A/250V Air switch?
If we go just by what is presently (12/15/2023) available at the Sonoff website (ZBMINI-L2-DOC - SONOFF Official) the only directive is to install a 10A/250V Air switch, and it seems that would have to be inside the electrical box along with the ZBMINIL2, right? I think we need to qualify the terminology
Let’s qualify what is meant by an “air switch.” This would not be the kind of switch used with some garbage disposals or hot tubs. I believe the Sonoff engineers are a referring to what’s known as any mechanically operated device that produces a gap (of air) in the electrical path.
Let’s look again at the language from the User Manual, from Step 2:
“Before installing the device, please install an air switch as the protective device (Air switch: 10A/250V).”
We must assume this means a 10A breaker (generically described as an air switch) since they refer to it as a “protective device.” In Step 1 they already instructed to turn the power off, so this is not for shock protection of the installer. We have to assume they mean overload protection for the 6A rating of these devices.
Now let’s qualify what a Residual Current Operated Circuit Breaker (RCOCB) is. These are typically used with DIN rails in industrial automation scenarios, but Residual Current [Device] (an RCD) refers to what is essentially a Ground Fault Device (ground fault being American terminology) that protects against current leakage. What? The following is a clue from Wikipedia:
A pure RCD will detect imbalance in the currents of the supply and return conductors of a circuit. But it cannot protect against overload or short circuit like a fuse or a miniature circuit breaker (MCB) does (except for the special case of a short circuit from live to ground, not live to neutral).
However, an RCD and an MCB often come integrated in the same device, thus being able to detect both supply imbalance and overload current. Such a device is called an RCBO, for residual-current circuit breaker with overcurrent protection, in Europe and Australia, and a GFCI breaker, for ground fault circuit interrupter, in the USA and Canada.
Okay, there’s a direct reference to the Miniature Circuit Breaker (MCB), and the only exact terminology to match the Sonoff documentation. So can we assume the Residual Current Operated Circuit Breaker (RCOCB) is a combination of an MCB and RCD (or GFCI)? I think so.
Now let’s define Miniature Circuit Breaker (MCB). Is this a tiny device that’s supposed to fit inside the electrical box with the ZBMINIL2? I don’t think that’s what Sonoff is trying to say, but who knows. There is certainly no off-the-shelf device like this being sold in the U.S. or Canada., that I could find. Here’s a couple definitions from Wikipedia, concerning what low-voltage and MCB mean:
Low-voltage (less than 1,000 VAC) types are common in domestic, commercial and industrial application, and include:
Miniature circuit breaker (MCB)—rated current up to 125 A. Trip characteristics normally not adjustable. Thermal or thermal-magnetic operation.
It seems to me that this all (Sonoff documentation) refers to the circuit breaker found in one’s typical electrical breaker panel, but the specification for 6A or 10A is not in line with what we typically have in our (U.S.) residential installations. For most of us (in the U.S., anyway) we’re going to find a 15A breaker installed on our lighting circuits. Does this mean we should change the 15A for a 10A breaker if we are using these Sonoff Mini switches?
If so, this will create other limitations in load capacity for a lighting circuit. For instance, if your bathroom light is on the same circuit as the outlet your wife uses for her hair dryer, the Sonoff Mini switches will not be suitable for such a circuit. The same goes for any 120V circuit load that goes over 10A/1200 watts. Remember Ohm’s Law: V/I=R, I=V/R, V=IR and IV=W (10A x 120V = 1200W).
These 10A breakers are not at all common in the U.S., and will likely need to be special ordered.
Looking forward to hearing the thoughts from the Community…