These chaps are appearing on AliExpress for < USD 10 ?

 

https://www.aliexpress.com/item/2P-63A-MTS-Dual-power-Manual-transfer-switch-Circuit-breaker-MCB-50HZ-60HZ-400/32267471000.html

 

In the interests of our members I bought one.

 

The two sides are interlocked, it's not possible to have both mains and genset connected at the same time ?

 

BUT!!

 

It is essential that you turn off the one that's on before turning on the one that's off!

 

Despite the interlock the two sides do connect at the same time (briefly, but they do connect) if you turn the off breaker on without turning the on breaker off.

 

So, to be certain, "both off" should be a part of your transfer sequence.

 

They are still infinitely better than using a lead with a plug on both ends or relying on your memory to turn one breaker off before turning the other on. Just be aware of the limitations.

 

Note, I've only tested the Tomzn 63A unit, others may be better (or worse) in this respect.

 

 

 

Good to know! That's the main breaker I used back when you were advising me on building my boxes just over a year ago. Fortunately I've been to swamped getting an alternative power source in yet.

I must be missing something, what happens if you don't follow these directions?

 

Kurt

35 minutes ago, kbelyeu said:

I must be missing something, what happens if you don't follow these directions?

 

Kurt

If the mains power is off and you connect your generator to the mains you provide 220v which can then be stepped up to many kv by the local transformer which is enough to kill or injure any PEA employee working on the supposedly dead power lines. 

 

This kind of incident (it isn't an accident) has killed or injured power line workers in quite a few countries.

 

The reverse of connecting mains power to a running generator I'll leave to someone better versed in the problems it can create, though extremely loud bangs and destroying some of your system could be included.

 

56 minutes ago, kbelyeu said:

I must be missing something, what happens if you don't follow these directions?

 

It's there in the OP:-

 

On 9/2/2018 at 6:08 PM, Crossy said:

Despite the interlock the two sides do connect at the same time (briefly, but they do connect)...

Having your genset and the mains supply connected at the same time is generally a bad idea potentially leading to death of your genset or some poor soul who's working to get your power back on.

 

In reality the flash connection is very short (I may get around to measuring it one day) and is unlikely to actually kill anyone or do serious damage. But why take the risk?

 

 

 

1 hour ago, kbelyeu said:

I must be missing something, what happens if you don't follow these directions?

 

Kurt

Depends.  With both sources, genny and mains in a live state there would be 2 x ~240V potentials in parallel for a few milliseconds which wouldn't be a problem. However if your genny was switched in but not running and you then switched to mains, the genny at 0V potential would briefly see the ~240V mains potential  applied to it's output - which it might not take kindly to.

As also identified above not a good idea to reverse feed ~240v back into the mains supply, which your electricity company workers may be assuming to be at 0V

 

As the OP has suggested best to be safe and ensure both off before switching one in.