Tool Problems - coincidence or did I botch my garage electrical wiring? (1 Viewer)

[Ruggedly]

Hey guys, so I just recently finished wiring up my garage after having a subpanel installed last summer. This was a very straightforward install, but since I'm a DIYer that knows just enough be dangerous (and stupid), I'm trying to figure out what's going on. I need to do some more testing, but for now I'm hoping you can tell me whether the issues I'm experiencing are more likely related to my wiring or something else.

What I installed:
On a 50 amp subpanel, I added three circuits:

• 15 amp 120V for lighting
• 20 amp 120V for upper row of outlets (above workbench)
• 20 amp 120V for lower row of outlets (knee height)

Each of the 20 amp circuits has about 10 outlets connected in series. The upper row is utilizing all brand new 15 amp outlets. The bottom row is reusing 15 amp outlets that I removed from inside our house a few months ago. All the wiring is 12 gauge (yellow) romex (black, white, ground).

I'm about to pick up a full multimeter, but utilizing a simple receptacle tester and the most basic of voltmeters (the kind that just lights up specifying 120V or 240V), all seems fine.

The Issues:
On the upper row of outlets, I ran my Jet contractor table saw for the first time since we've moved into this new house this past weekend. Much of the time, I would simultaneously have my shop-vac running on the lower row of outlets for dust collection. For the first few minutes, the saw seemed stronger than I'd ever experienced it, which made sense since it was the only thing running on upper row 20 amp circuit. However, after some time, the saw started tripping it's internal breaker, and each time seemingly doing it under less and less stress. One time it even tripped while running idle (no wood being fed).

Sidenote: At my old house, the garage electrical was a horrible afterthought, so the saw would easily bog down and it's internal breaker would trip, so I'm used to that happening in a poor electrical configuration. However, doesn't this new behavior imply a similar amperage drop in the system? Or could it be something faulty in the saw?

Two nights ago I was running my oscillating spindle sander (the Ridgid belt/spindle combo version) on the LOWER row of outlets. I noticed similar behavior where it was starting to bog down under some pressure. Then the sander binded up and started smoking! Here's a link to a video showing the behavior. I thought I had completely smoked it. However, about 15 minutes later I went back out and it started right up.

Other tools have not shown any issues (jig saw, shop vac, etc.)

All this being said, it sure feels like these are related to the tools being underfed, but yet they start out strong? It does seem like the issue is associated with the tools I'm keeping on for an extended period (5-10 minutes without powering down). What could this mean?

Any help is appreciated!!!

Thanks.

David

One additional note: Not sure if it's related, but when turning on the sander the other night, I noticed a slight flicker/dimming of my shop lights, which are on a completely different circuit. It got me wondering if the whole subpanel was getting bogged down. There are a few other circuits on the panel, the only one of real substance is the washer/dryer, but the dryer is gas, so even if they were running, I can't imagine a big draw.

 

[Bob Morazes]

Hey David,
There seems to be a bit of discussion on whether house outlets are in series or parallel.
The attached pic is a proper wiring method.
For me this method makes more sense., than the series where all the juice runs through each outlet.

Think of it like plumbing.
The black wires and white wire continue from the beginning to the end of the run. and each outlet is pigtailed off the main pipe/wire, like a sink or toilet in plumbing.
Thus each outlet is just sipping off the main line instead of the main line running through each one.

Try rewiring a few of the first outlets like this and leave the rest of the run disconnected and see if it helps.
Bobmo

 

[Ruggedly]

Hey David,
There seems to be a bit of discussion on whether house outlets are in series or parallel.
The attached pic is a proper wiring method.
For me this method makes more sense., than the series where all the juice runs through each outlet.

Think of it like plumbing.
The black wires and white wire continue from the beginning to the end of the run. and each outlet is pigtailed off the main pipe/wire, like a sink or toilet in plumbing.
Thus each outlet is just sipping off the main line instead of the main line running through each one.

Try rewiring a few of the first outlets like this and leave the rest of the run disconnected and see if it helps.
Bobmo

View attachment 1916055

Bob,

Thanks for the reply. So you think I might be losing amperage through the outlets themselves? It's frustrating to think this could be the case (especially when it's is how I've always seen outlets wired), but I can see the logic behind it. I'm not looking forward to rearranging things to regain access to the outlets, but if this could solve the problem, it'll be worth it. Thanks again.

David

 

[doug720]

Beyond the garage wiring and sub panel -

What feeds the garage?

How far is main panel from sub panel?

What size wire was used between sub and main?

What is main panel Amp rating?

Was a large load being used at main panel at same time?

Is the main panel getting good supply- voltage drop?

 

[Ruggedly]

Beyond the garage wiring and sub panel -

What feeds the garage?

How far is main panel from sub panel?

What size wire was used between sub and main?

What is main panel Amp rating?

Was a large load being used at main panel at same time?

Is the main panel getting good supply- voltage drop?

The garage is fed by a subpanel that was professionally installed to code in the garage. I know he used large gauge aluminum wire (which limited me to a 50 amp panel instead of the 60 amp I was originally pursuing).

The sub panel is probably 60 feet (of wire) from the main panel.

I don't know what size aluminum wire was used, but as mentioned above, it limited me to a 50 amp sub instead of 60 amp sub, so maybe between that piece of info and the distance of the run, it can be deduced? Otherwise, I can look when I get home tonight.

The main panel is a brand new 200 amp system installed back in June.

Other than standard lighting, baby's sound machine, etc., the only heavy electrical items are our mini split units, which have a dedicated 30 amp circuit. I can't imagine anything pulling anywhere near capacity.

How could I test whether the main panel is getting good supply?

Thanks!

 

[Bob Morazes]

Bob,

Thanks for the reply. So you think I might be losing amperage through the outlets themselves? It's frustrating to think this could be the case (especially when it's is how I've always seen outlets wired), but I can see the logic behind it. I'm not looking forward to rearranging things to regain access to the outlets, but if this could solve the problem, it'll be worth it. Thanks again.

David

My dad taught me to wire the other way, and it was ok for the house where there was a TV, radio, and maybe a vacuum cleaner going, and I seem to remember the vacuum slowing down when the toaster was plugged in, or the fuse blowing.
That was 50 years ago and slight bit of wisdom, to electrical flow have happened.
I'll get booed here but it you have a GF outlet (the square pieces of crap) in there take it out.

do a test with the first outlet and see what happens.
Maybe there are some electrical wizards out there, that have the magic answer.

bobmo

 

[Ruggedly]

By GF, do you mean GFCI? or literally the rectangular-style outlets? I don't have any GFCI outlets in there, but the top row of outlets are all the newer rectangular-style outlets. The lower row are the traditional round/oval style like shown in your diagram above. I can't imagine the style making a difference?

 

[Bob Morazes]

By GF, do you mean GFCI? or literally the rectangular-style outlets? I don't have any GFCI outlets in there, but the top row of outlets are all the newer rectangular-style outlets. The lower row are the traditional round/oval style like shown in your diagram above. I can't imagine the style making a difference?

I was referring to the GFCI, so your safe.
But now that you mention it. Do you know the amperage rating of your square outlets?
Bobmo

 

[Ruggedly]

I was referring to the GFCI, so your safe.
But now that you mention it. Do you know the amperage rating of your square outlets?
Bobmo

All the outlets are 15 amp.

 

[Music Man]

Get a vom and measure the voltage across the plug. Hopefully it isn;t 230vac that you are feeding to the tools!

 

[Ruggedly]

Get a vom and measure the voltage across the plug. Hopefully it isn;t 230vac that you are feeding to the tools!

I have confirmed this isn’t the case. My receptacle tester would tell me that much.

 

[KLF]

(pssstt.... All garage receptacle circuits are required to have GFCI protection, per NEC)

Hey, who let @decavo in here?

 

[Ruggedly]

(pssstt.... All garage receptacle circuits are required to have GFCI protection, per NEC)

Hey, who let @decavo in here?

Haha yeah I read that! I thought it was supposed to be a GFCI breaker though?

 

[KLF]

You can do it with a GFCI breaker, or just put a GFCI receptacle as the first one in the line, then feed all the other receptacles from that one. It will protect the downstream receptacles.

I don't get the hate for the GFCI protection? I've been doing this for years, I run my woodshop and all my garage tools through them, never have a problem with false trips or voltage weirdness.

 

[Ruggedly]

Any thoughts on what’s causing mine then?

You can do it with a GFCI breaker, or just put a GFCI receptacle as the first one in the line, then feed all the other receptacles from that one. It will protect the downstream receptacles.

I don't get the hate for the GFCI protection? I've been doing this for years, I run my woodshop and all my garage tools through them, never have a problem with false trips or voltage weirdness.

 

[e9999]

you say it's the tool internal breaker that trips, not the panel. That suggests high current in the tool. (Of course, the current will be the same in the circuit but the panel breaker is likely less sensitive. Unlikely a breaker would trip because of amp loss as you seem to think, from what I know.) That in turn suggests low voltage at the tool. Measure the voltage at the outlet to the tool with a voltmeter and see what happens when the tool is running. If it dips precipitously you have some unwanted resistance (small wires, poor connections etc). You can easily do that with one of the 10x clamp current probes that plug directly in the outlet and have outside connectors for voltmeters, about $15, without the need for tapping in the outlet or wiring. You'll know much of what you need to know. Then the next step up if you're interested or desperate would be to measure the current there with a clampmeter ($50) and you'll confirm why and when your breaker is tripping. If you are not that familiar with electrical circuits be careful.

 

[rkymtnflyfisher]

What is the actual voltage at your receptacles?

What is the voltage at the same receptacle when your saw is running.

Tell us this.


Also, you ran #12 romex, why did you go with 15 amp circuits?

 

[KLF]

Also, you ran #12 romex, why did you go with 15 amp circuits?

The receptacle branch circuits are on 20A breakers, so a #12 wire is the correct size (assume the length is not too long). He only has 15A rated receptacle devices in the boxes, but that is acceptable per NEC (since he has more than one device in the circuit). If it was a single dedicated receptacle on a 20A circuit, then it would need to be a 20A rated device.

I would get a RELIABLE voltage meter, put it on the circuit and run the tool, watch what the voltage does. A clamp-style ammeter would also be helpful, if you can get one.

 

[Ruggedly]

you say it's the tool internal breaker that trips, not the panel. That suggests high current in the tool. (Of course, the current will be the same in the circuit but the panel breaker is likely less sensitive. Unlikely a breaker would trip because of amp loss as you seem to think, from what I know.) That in turn suggests low voltage at the tool. Measure the voltage at the outlet to the tool with a voltmeter and see what happens when the tool is running. If it dips precipitously you have some unwanted resistance (small wires, poor connections etc). You can easily do that with one of the 10x clamp current probes that plug directly in the outlet and have outside connectors for voltmeters, about $15, without the need for tapping in the outlet or wiring. You'll know much of what you need to know. Then the next step up if you're interested or desperate would be to measure the current there with a clampmeter ($50) and you'll confirm why and when your breaker is tripping. If you are not that familiar with electrical circuits be careful.

Thanks for this guidance. I've got a clamp meter with probes coming on Sunday. I'll follow your guidance for testing then. If the voltage turns out to be low at the outlet to the tool, would it be a solid strategy to go down the line and test each outlet, getting closer and closer to the panel, to try to isolate where the voltage drop is occurring? Unless it's somehow an incremental drop through each outlet, I'm assuming I'm going to find a single outlet that's the source of the problem?

 

[Ruggedly]

What is the actual voltage at your receptacles?

What is the voltage at the same receptacle when your saw is running.

Tell us this.


Also, you ran #12 romex, why did you go with 15 amp circuits?

I have a clamp meter with probes coming Sunday, so I'll be able to test it then. Looks like @KLF already responded regarding the circuits. They're 20 amp circuits, just with 15 amp outlets.