Question for electricians

alexinPA · Jun 30, 2025

Finally bought new generator Westinghouse 9 kw. Installed manual disconnect switch with 50 amp cable so the whole house will be supplied during power outage. Would be nice to monitor output wattage... Found this on Amazon
The problem is 10 awg cable. 10 awg supposed to support 30 Amp. Sent txt to the seller and his answer:
"The short distance (1.3 ft) means that the resistance is low and the cable is resistant to high temp., so it can pass 50 A current".
I find it hard to believe. Any opinions? Are there other similar gadgets? Don't want to overload the generator.

mrmikey · Jun 30, 2025

What about one like this instead although it would only measure on leg so you'd need two.

alexinPA · Jun 30, 2025

mrmikey said:
What about one like this instead although it would only measure on leg so you'd need two.
View attachment 3684256

Thanks. It’s cable I got. Can’t separate wires

mrmikey · Jun 30, 2025

There's no separate wires anywhere in the circuit you can get the pickup around?

greenie · Jun 30, 2025

Electric water heaters and ranges are usually fed with 10/2 or 10/3 romex and a 30 amp fuse - however if you look at the wires inside the appliance they're usually 12AWG. Those wires are short runs so it works. The Amazon amp meter with its 10 AWG wiring is a short run and should be OK. If you're like me you'll monitor the amp meter and see which appliances you can run simultaneously and then once you know the meter will come off and sit in a drawer. The generator will sit outside, as will the meter. Worse case scenario, in the unlikely chance the meter wires or gauge overheats, it's outside anyway. The Amazon amp meter is really unique, I did a quick search and couldn't find anything else that would let you monitor 50 amps without tapping into or separating the two 120V legs. It's inexpensive too.
Your generator should have breakers on the 240 output, if you exceed the breaker rating the breaker will open. Keep in mind that anything with a motor has a momentary heavier draw than the normal operation (AC, Freezer, Refrigerators, water or sewage pumps) so if you're running close to the output of 9KW (37.5 amps), the starting factor of motors should be considered.
I'm no electrician but I'd use the Amazon meter and get a feel for what you can run simultaneously and then put the meter away. 9KV will require careful use of electric in the home to avoid tripping the generator breaker.
Generators can have some really odd outlets for 240, they vary by amperage and aren't interchangeable. I'd suggest taking a close look at the Amazon meter's plugs to make sure they'll fit the generator's outlet and whatever you're connecting the house with.
Hope this helps.

camshawn · Jun 30, 2025

In theory, it would probably work…..but….. I would not purchase it unless it is “approved “ by UL or a similar standards agency.

WranglerX · Jun 30, 2025

And what is gauge of cable you are connecting generator to transfer switch.....

Bottom line with 30 or 50 amp generator ( maybe 10KW) you need to cut back on what is turned on in house....... IF you were to have 20-25KW generator you could turn everything on....

grsthegreat · Jun 30, 2025

In all honesty, a 9kw generator can only supply 37 amps at 240volts.

Camofurever1 · Jun 30, 2025

What type of cable is it (look on the cable jacket) and what Temp rating in C is it? That will determine your Max amperage rating. NEC states that a #10 is only good for 40A, if the wire insulation is rated for 90C and it is a copper conductor. The only other way a #10 would be rated higher is if it was a single wire conductor and it was in free air. Then it would be rated for 55A. (which in your application, wouldn't apply, as it has 2 current carrying conductors in a cable.) You don't get to increase amperage ratings because the cable is short. Also, there is no such thing as a #9 gauge wire. Even if it was in IEC standards, they would use a mm squared for wire size. I would steer away from that device. If it caught your house on fire because it doesn't meet NFPA 70 (NEC) or have a UL listed or recognized part label affixed to it, insurance might not pay out. UL is more stringent on wire ampacity, as the do not recognize any general wire insulation over 75C.