Contractor Talk - Professional Construction and Remodeling Forum banner
1 - 20 of 25 Posts

·
Registered
Joined
·
438 Posts
Discussion Starter · #1 ·
Hey guys. Deck builder/remodeler here with an electrical question.

Last week, due to the heat, we had power outages where we were working.

So I fired up my 8000 watt generator and plugged in a small 10 amp compressor. No problems at startup. But the compressor would blow the genny's breaker after about 30 seconds.

Since this generator has no problems running two 15 amp miter saws at the same time, I figured there was something wrong with the compressor. Tried my larger Makita 12.3 amp compressor. Same thing. It would start up fine (when it takes the most juice) but blow the breaker on the genny after 30-40 seconds.

I tried both 120v outlets AND the 30 amp 120/240 with the proper cord.

Is there something different about a compressor motor and a saw motor? What gives?
 

·
Head Grunt
Joined
·
3,270 Posts
What 480 is saying is there is a difference in the load between the tools. What a tool states for amp rating does not mean that is the amp draw that it uses. An air compressor is under load from start to stop where a saw may be free wheeling or under very little load. You put a dull blade on that saw and drive it into a long cut and you will see the generator trip off again. I myself think it is the generator. My Honda 2000I will power up my porter cable pancake compressor with no issues although it will not run my 30gallon craftsman. It is tough to find a good generator that will power any good size air compressor. Some generator manufacturers will over rate the output of the unit and some manufacturers are more accurate. This is one reason why Honda's are so popular, their output numbers seem to be more accurate.
 

·
Registered
Joined
·
4,165 Posts
Don't electrical motors pull something like 3x rated amps on start up? Have no idea have much amperage a compressor pulls in relation to rated amps, when it kicks back on when it may already have 80lbs or whatever of pressure in it.

Wonder if a higher rated capacitor could be used to help in those situations.
 

·
hurtlocker
Joined
·
555 Posts
I dont know anything about this technical stuff
But I have wrecked 2 generators with what I believe to be electric comp related(this is not scientific)

Since having a no comp on gen rule I have had zero issues with premature gen retirement?
 

·
Working
Joined
·
4,127 Posts
This may sound odd but I had this problem with a smaller 3500 watt gen. So I called the manufacturer and they asked if it was grounded how the instructions say. I never read them so no.
They want a minimum of a 2' grounding rod and 10gauge or greater wire to the grounding post. After that it wouldn't trip the breakers running the saws.

Cole
 

·
Registered
Joined
·
4,165 Posts
This may sound odd but I had this problem with a smaller 3500 watt gen. So I called the manufacturer and they asked if it was grounded how the instructions say. I never read them so no.
They want a minimum of a 2' grounding rod and 10gauge or greater wire to the grounding post. After that it wouldn't trip the breakers running the saws.

Cole

Do people actually do that? :whistling
 

·
Registered
Joined
·
70 Posts
This may sound odd but I had this problem with a smaller 3500 watt gen. So I called the manufacturer and they asked if it was grounded how the instructions say. I never read them so no.
They want a minimum of a 2' grounding rod and 10gauge or greater wire to the grounding post. After that it wouldn't trip the breakers running the saws.

Cole
Ya gotta be kidding on that one.

The main issue is the generator interal bonding I know some portable generators they will have floating netural and grounding system but some will bond both netural and ground at the generator.

Merci.
Marc
 

·
Registered
Joined
·
70 Posts
Hey guys. Deck builder/remodeler here with an electrical question.

Last week, due to the heat, we had power outages where we were working.

So I fired up my 8000 watt generator and plugged in a small 10 amp compressor. No problems at startup. But the compressor would blow the genny's breaker after about 30 seconds.

Since this generator has no problems running two 15 amp miter saws at the same time, I figured there was something wrong with the compressor. Tried my larger Makita 12.3 amp compressor. Same thing. It would start up fine (when it takes the most juice) but blow the breaker on the genny after 30-40 seconds.

I tried both 120v outlets AND the 30 amp 120/240 with the proper cord.

Is there something different about a compressor motor and a saw motor? What gives?
What brand name that genny it is?

with cheap one when it get loaded up pretty good the HZ and voltage will drop unless the engine govner is right on the track with it.

For most generators for unloaded it will run about 62 or 63 HZ once it get loaded it will drop to good 60 HZ but once you drop below 60 HZ you will run some issue with it.

Most portable genny are set up to run at 3600 RPM loaded unloaded it should be about 3700 or so.

And most of cheap one they have kinda pretty crappy voltage regualtion { 2 V per HZ } so if running right you should have good 120 volts at 60 HZ anything else you may have weak voltage regulator or bad capaitor.

Merci.
Marc
 

·
Service & Repairs
Joined
·
4,001 Posts
Uh, maybe, hey you never know -- the generator's circuit breaker might have shut off prematurely because it was basking in the sun and was hot. Try keeping it a cool place. I know that's hard to do out on the job but heat plays an enormous factor on electrical equipment.
 
1 - 20 of 25 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top