Electrical Question: 20A tools on a 15A breaker

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Forum topic by Cougar posted 12-27-2013 04:01 PM 2705 views 0 times favorited 16 replies Add to Favorites Watch
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11 posts in 1610 days

12-27-2013 04:01 PM

Topic tags/keywords: question electrical


I am looking at buying a bandsaw and Grizzly is having a sale on a 2hp model that can be wired for 110 or 220. I rent a house and have a garage shop with a terrible electrical situation – one outlet (for the fridge) and one outlet on the ceiling for the garage door opener. I am going to run a couple of extra boxes so I can power my tools. The two garage breakers are 15A. The Grizzly BS draws 20A at 110V. Can I run this tool on the outlet, or will I trip the 15A breaker everytime I start? I will usually run an air filter, a dust collection unit, lights, and one power tool at a time. I also tripped breakers fairly often at my old house when I ran my shop vac and a 15A table saw on a 20A breaker. Now that I am using a more powerful dust collector, I am going to try to isolate the air filter and DC on one breaker and have the power tools on a dedicated breaker to keep from tripping it constantly. My other option is to buy a standard 15A 1 1/2 horse power bandsaw (Rikon) to run on the 15A breaker. I am a renter, so doing what I want to do, rewire the entire garage with high amerage breakers and some 220v lines, is not going to happen. The best I can do is add more outlets to the existing lines.

16 replies so far

View darthford's profile


601 posts in 1920 days

#1 posted 12-27-2013 04:26 PM

Read the owners manual that saw wired for 110 will require a 30A breaker and wire/cords rated for 30A e.g. 10 gauge. You are not even close with a 15A 110 outlet. I’d also be reading the Rikon manual if its going to draw 15A my guess is you will need a minimum 20A breaker, and again wire rated for 20A. If they specify a 15A breaker then you are fine, but probably can’t operate anything else on that circuit. I know one thing you don’t want tools tripping breakers in the middle of a cut.

View Cougar's profile


11 posts in 1610 days

#2 posted 12-27-2013 04:36 PM

Darth: is it normal for tools to trip in the middle of the cut? I have rudimentary electrical knowledge, but my experience is that amperage is usually highest at start up or when a tools is under load. I have only experienced a tripped braker when I turn a tool on, never during a cut. Though, I supposed if I am resawing 12” of maple…

View Fred Hargis's profile

Fred Hargis

4984 posts in 2489 days

#3 posted 12-27-2013 05:08 PM

They will trip in the middle of a cut. What happens is that the work load applied slows the motor down below it’s stated speed, it tries to get back to that stated speed by drawing more juice. When that exceeds the load capacity of the breaker it trips.

-- Our village hasn't lost it's idiot, he was elected to congress.

View CharlesA's profile


3319 posts in 1793 days

#4 posted 12-27-2013 05:09 PM

Breakers can trip in the middle of a cut if the wood binds the blade. Also, if you’re cutting thicker wood the load will be heavier in the middle of a cut than at the beginning. I was cutting some 2” SYP that was pretty squirrelly as it was ripped and would squeeze the blade even with a splitter.

-- "Man is the only animal which devours his own, for I can apply no milder term to the general prey of the rich on the poor." ~Thomas Jefferson

View darthford's profile


601 posts in 1920 days

#5 posted 12-27-2013 05:24 PM

If you are running right on edge of the breaker rating or in this case way over yeah it can trip at any time. Breakers can absorb a startup hit, think slo-blo fuse. My Grizzly cyclone is rated to run on a 110 20A breaker but at startup it pulled…wait for it…70amps as measured with a Fluke meter. I found it was highly unstable on a 20A 110 breaker and frequently tripped within a few minutes after startup. I had to rewire it for 220A.

Don’t start a fire and burn the guy’s house down. ;-)

View dbray45's profile


3320 posts in 2772 days

#6 posted 12-27-2013 05:31 PM

yep 20amp load will trap a 15 amp breaker.

Run a new circuit for 30 amp load.

-- David in Damascus, MD

View danoaz's profile


222 posts in 2166 days

#7 posted 12-27-2013 05:38 PM

I vote yes to everything the other commenters are saying here. I am in a similar situation with a planer and DC on the same circuit. It all starts up fine but as soon as the planer starts digging it trips the breaker. I need an electrician…sigh.

-- "Simplicity and repose are the qualities that measure the true value of any work of art." Frank LLoyd Wright

View Shawn Masterson's profile

Shawn Masterson

1325 posts in 1944 days

#8 posted 12-27-2013 07:27 PM

You never know burning the guys house down might be doing him a favor. Just teasing

View UpstateNYdude's profile


916 posts in 1979 days

#9 posted 12-27-2013 08:08 PM

How big is the panel box? If it’s a 100amp box why not run a couple a 20a 220v lines out for your tools and save the hassle of switching to a smaller tool, all you need is 12/2AWG wire, 20A breakers and receptacles and your off to the races.

-- Nick, “I am always doing what I cannot do yet, in order to learn how to do it.” – Vincent Van Gogh

View Pezking7p's profile


3217 posts in 1647 days

#10 posted 12-27-2013 08:18 PM

If you need more juice, ask your landlord if you can have the work done. He’ll probably be fine with it as long as the work is permitted and inspected (and completed).

-- -Dan

View SCOTSMAN's profile


5849 posts in 3581 days

#11 posted 12-27-2013 08:59 PM

Go for the 20 amp it will be best all round. MY big saw kept tripping at start up till I changed the trip switch to a higher rating now it’s fine every time . Alistair

-- excuse my typing as I have a form of parkinsons disease

View distrbd's profile


2252 posts in 2442 days

#12 posted 12-27-2013 09:09 PM

I could be wrong but you can not replace a 15 AMP fuse with a 20 amp :cut and paste from Google:
Although it is possible to replace a 15 Amp fuse with a 20 Amp fuse, it is not advisable because upping the fuse scale can damage the wires through overheating. This occurs due to high current levels in the circuit which can be hazardous as they are a potential for an electrical fire.

-- Ken from Ontario, Canada

View distrbd's profile


2252 posts in 2442 days

#13 posted 12-27-2013 09:11 PM

Here’s the reason better explained:

. The 15 amp fuse will be protection a #14 wire which is rated for 15 amps maximum capacity. By changing the 15 amp fuse to a 20 amp fuse you would then be allowing 20 amps maximum

-- Ken from Ontario, Canada

View dbray45's profile


3320 posts in 2772 days

#14 posted 12-30-2013 12:36 PM

Alistair – You really don’t want to do that. I don’t know about there but here in the colonies, if you have a fire for any reason, your insurance company will not pay for the damages because your panel is not in code. It doesn’t matter if the fire was because of bacon grease catching on fire on the stove, they won’t pay.

-- David in Damascus, MD

View canadianchips's profile


2600 posts in 2993 days

#15 posted 12-30-2013 12:57 PM

An option might be running 1 heavier wire from main panel to sub panel in your workshop..
Ex: 40 amp breaker in main panel,use #8 wire to sub panel in shop.sub panel can then have separate 20amp. Breakers.
Not sure how far away workshop is from mai panel. Get an electrician to give you specs. On what size wire you will need.

-- "My mission in life - make everyone smile !"

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