New Sonoff has no fuse

[K3NS31]

Hey All

I just bought 2x Sonoff TH16s and opened up one to find that it has no fuse. One of the reasons I bought this version was because it is (or was) fused.
Is there some other safety feature on the newer Sonoff's that's allowed them to remove the fuse? Or is it just unprotected now?

I want to use it to control a 2500W oil fin heater. Should I add a fuse to the power lead myself? Or am I being overly paranoid? The mains breaker should trip if there are any problems, right?

Thanks

 

[DA-LION-619]

Are you sure there was a fuse? Last I recall, the entry level could only handle about 10A(TH10) and this can do 15A but I never saw a fuse mentioned.

 

[K3NS31]

Are you sure there was a fuse? Last I recall, the entry level could only handle about 10A(TH10) and this can do 15A but I never saw a fuse mentioned.

yep. plenty pics and vids online of TH16s with fuses.

The question now is, do I need to use a fuse or can I just rely on my mains circuit breaker?

 

[hilton]

I think the newer ones have a built in fuse so not replaceable. I'm running rev-2 TH16s that switch my geyser and pool. No real problems so far.

 

[K3NS31]

I think the newer ones have a built in fuse so not replaceable. I'm running rev-2 TH16s that switch my geyser and pool. No real problems so far.

That sounds promising. How would you know if it had a built-in fuse? Can you see it on the board?

 

[Geoff.D]

A 15A device for a pool and geyser? Pushing your luck you guys are!

What is the CB feeding that circuit? for multiple numbers of power sockets? (20A) ?

 

[Geoff.D]

I think the newer ones have a built in fuse so not replaceable. I'm running rev-2 TH16s that switch my geyser and pool. No real problems so far.

Sonoff TH16 is a Sonoff version that can monitor and set temperature and humidity through the APP eWeLink. Just as the name indicated, the new version Sonoff TH device supports two power supply specifications- 15A. It supports pre-set temperature and humidity range, when the temperature and humidity of the environment falls into the range, it will automatically turn on or turn off connected devices.
The device supports connecting to three kinds of temperature and humidity sensors (AM2301, DS18B20, Si7021). Actually, Sonoff TH16 can work as a Sonoff when without connecting to sensors. But compared to Sonoff, Sonoff 10 is more safer, less radiation and in bigger size, easy operation. Most importantly, with the support of latest ewelink app, you can create chains of simple conditional statements(Smart Scene). This means you can use the them with temperature and humidity sensors (AM2301, DS18B20, Si7021) to collect data, while these data can be shared to other ITEAD smart home devices(Sonoff, Sonoff RF, Sonoff SV, Slampher, smart socket, etc.) under your account, thus other devices can use the data to control connected appliances. This device is perfect to work with electric fan, air conditioner, humidifier.

**Please note that this unit is Wi-Fi only. Please do not use on Geysers**.

* The temperature sensor port is a live port and requires the device to be powered OFF before plugging in the sensor or damage will occur *

 

[hilton]

That sounds promising. How would you know if it had a built-in fuse? Can you see it on the board?

Sorry I have POW-R2 boards that run my geyser and pool. I'll pull it open it when load shedding hits next. Maybe I have one in my workshop, let me go and have a look.

 

[hilton]

A 15A device for a pool and geyser? Pushing your luck you guys are!

What is the CB feeding that circuit? for multiple numbers of power sockets? (20A) ?

I mistakenly said TH16 but they are POW-R2s. One Sonoff per load and a dedicated mcb per line.

 

[Geoff.D]

I mistakenly said TH16 but they are POW-R2s. One Sonoff per load and a dedicated mcb per line.

Sonoff Pow R2 is a 15A WiFi smart light switch that allows you to remotely manage and control your appliances and monitor your home energy usage. The WiFi light switch works like a power monitor, which allows you to keep track of 99% accurate real-time current, voltage and power on your app.

The power switch can protect your appliances from overload. What you need to do is to set threshold values for the current, voltage and power. It works like a kwh calculator that can measure electricity consumption for a specified period and a day. The eWeLink app provides 100 days recorded electricity usage data, which you can export to your phone storage. You can keep track of how much energy your appliances are consuming and estimate your running costs.

With the Pow R2 power monitoring switch, you can spend less on your electricity bill. The timers schedule your appliances automatically power on and off at a defined time. The scene lets your appliances work together in new ways, like setting the heater auto-off when the door light is off.

** Please do not use on Geysers**

The same issue, the 15A rating is just too low for geysers and especially motor circuits.

Used in conjunction with contactors or SSRs maybe.

 

[one poster]

The mains breaker should trip if there are any problems, right?

The breaker tripping after the sonoff caught fire will not be much help.

yep. plenty pics and vids online of TH16s with fuses.

There are also plenty pics of sonoffs that went up in flames... some of them specifically because the fuse holders used seemingly were not rated correctly for the current.

There are many people using sonoffs to run pools and/or geysers but I feel very reluctant to have a sonoff be the main "switch" that has >10A going through it (EDIT: even a POW R2 or TH16 rated at 15A)

One of the other theories why some sonoffs go smokey is that the terminals do not clamp the bare copper wire sufficiently or are too small, leading to possible shorts and/or arcing. Putting a sonoff on an extension lead that will potentially see movement on the cable would make a problem more likely.

If you add an inline fuse it should protect the extension lead if it draws too much current and overheats. The fuse has no way to know that the PCB of the sonoff is overheating though.

 

[hilton]

A 15A device for a pool and geyser? Pushing your luck you guys are!

What is the CB feeding that circuit? for multiple numbers of power sockets? (20A) ?

Thanks for the advice, I'll look at getting a relay to switch the geyser.

 

[Geoff.D]

Read all about it on the power forum:

 

[AntennaMan]

I've maintained for a long time that the Sonoff's aren't suited to high current applications, like a geyser. There just isn't enough of a safety margin built into them, even when they are built correctly.
If I were to use a Sonoff, then I would only use it to switch a correctly sized contactor.

 

[hilton]

I've maintained for a long time that the Sonoff's aren't suited to high current applications, like a geyser. There just isn't enough of a safety margin built into them, even when they are built correctly.
If I were to use a Sonoff, then I would only use it to switch a correctly sized contactor.

That's what I'm going to do then. In fact surely a 4CH PRO will do the trick as there's no current flowing through that as it just switches the output as a relay?

 

[Kosmik]

Read all about it on the power forum:

I agree about geysers but pool pumps load is very low. Stressed about it being borderline so used a pow r2 to measure, max draw is 2A which is negligible.

Avg usage is 3.5kwh per six hour window.

 

[one poster]

That's what I'm going to do then. In fact surely a 4CH PRO will do the trick as there's no current flowing through that as it just switches the output as a relay?

Even a sonoff basic would likely be fine according to me - it will depend on what is required to energise/activate your external relay/contactor. (but that should be way less than when a 2000W load runs through the sonoff).

EDIT: so there will be current through a sonoff when using an external relay/contactor

 

[one poster]

I agree about geysers but pool pumps load is very low. Stressed about it being borderline so used a pow r2 to measure, max draw is 2A which is negligible.

Avg usage is 3.5kwh per six hour window.

geyser and pool pump are actually too generic terms (some geysers have 2000W elements while others have 3000W... some pool pumps are 500W others maybe 1500W).

While I think it is less likely to lead to overheating on a sonoff, even a smallish pool pump will have an inrush current easily up to 7 times the general running current. So the components in the sonoff might still fail unexpectedly for what looks like a small load.

 

[Geoff.D]

That's what I'm going to do then. In fact surely a 4CH PRO will do the trick as there's no current flowing through that as it just switches the output as a relay?

Yes. That is the idea. Installed in a separate DB with either contactor's or SSRs. There is a thread somewhere on this started by @Arthur dealing with this topic. The sonoff only then carries the switching current, not the geyser or motor load current.
The same applies to most of these digital timers for geyser control. All of then suffer the same fate in the end, they simply can't handle the load currents. And if you do but them, oversize by 25% to at least 20A . the 16 A versions are just not good enough.

 

[Arthur]

Yes. That is the idea. Installed in a separate DB with either contactor's or SSDs. There is a thread somewhere on this started by @Arthur dealing with this topic. The son off only hen carries the switching current, not the geyser or motor load current.
The same applies to most of these digital timers for geyser control. All of then suffer the same fate in the end, they simply can't handle the load currents. And if you do but them, oversize by 25% to at least 20A . the 16 A versions are just not good enough.

Here's the link: https://mybroadband.co.za/forum/threads/remotely-turn-the-geyser-on-and-off.1102048/post-26208895

I subsequently changed the Sonoff Basics for Sonoff Minis.
All worked well - remotely switched from USA as needed when I had family guests in my house over the last holidays. So far all works.