Are one of these fuses blown?

[David Jones]

I'm trying to get my table saw up and running after a long term hiatus......are one of these fuses blown? They both look like they used to be almost the same color, etc...but the one on the bottom has a tarnished chalky color now (blown?). Sorry for such a dumb question, any help would be appreciated.

Thank you/Aloha
Dave Jones
Honolulu, Hawaii

[Keith Westfall]

If you had an ohm meter, you could tell right away...

Hard to tell just by looking I would think.

[jared herbert]

You can never really tell by looking at them. Put them back in the circuit, turn the power on and I use just a simple regular light bulb in a pig tail to check current on both ends of the fuse. Just touch one wire from the pigtail to the common terminal in the box and the other wire from the pigtail to what is supposed to be the hot side of the fuse. If the bulb lights up on both ends of the fuse it is good. A real low tech tool to use and it works good. It has saved me many service calls to an electrician. What I call pigtail is just a socket that you screw a light bulb in to with two wires connected to it, you should be able to get one at any hardware store. Jared

[Dan Hintz]

You can never really tell by looking at them. Put them back in the circuit, turn the power on and I use just a simple regular light bulb in a pig tail to check current on both ends of the fuse. Just touch one wire from the pigtail to the common terminal in the box and the other wire from the pigtail to what is supposed to be the hot side of the fuse. If the bulb lights up on both ends of the fuse it is good. A real low tech tool to use and it works good. It has saved me many service calls to an electrician. What I call pigtail is just a socket that you screw a light bulb in to with two wires connected to it, you should be able to get one at any hardware store. Jared
I'm going to suggest against a seriously dangerous practice...

[Jerome Stanek]

I use just a simple continuity tester.

[Stephen Cherry]

Or, if you don't have a meter, you could take a 9 volt battery, and place one of each of the fuses on the battery, and the other end on your tongue. If you get zapped, the fuses are both OK.



(just joking) Why not treat yourself to a Christmas present and get a multimeter? You can spend whatever you want, and they can all check fuses.

[Jerome Stanek]

If you check you can probably get a coupon from harbor freight for a free multimeter. or $2.00

[Chuck Wintle]

+1 for an ohmmeter. There are many inexpensive models available to check simple continuity. Avoid probing around with a light bulb...this is potentially hazardous to the health.

[del schisler]

I'm trying to get my table saw up and running after a long term hiatus......are one of these fuses blown? They both look like they used to be almost the same color, etc...but the one on the bottom has a tarnished chalky color now (blown?). Sorry for such a dumb question, any help would be appreciated.

Thank you/Aloha
Dave Jones
Honolulu, Hawaii

don't have a ohm meter ?? find one and ohm it out. Or take it to a electrial shop and ask them to measure. or get a couple new one's. Their are other way's but if you don't know how to tell if one is blown i won't go into other way's to tell . You can't just look at these like the other's that have a glass to see in .

[David Helm]

I'm going to go a different way. It looks to me like you are overdue for an electrical system upgrade. A new panel with breakers instead of fuses and an upgrade to 200 amps. You likely only have 60 amps with a fused panel.

[Kyle Iwamoto]

Interesting. 1 amp fuses? Must be in the control circuit. Must be a very old saw. Have not seen fuses in a long time. +1 on multimeter. That is really the only way to test fuses. Safely.

[Rod Sheridan]

I'm going to go a different way. It looks to me like you are overdue for an electrical system upgrade. A new panel with breakers instead of fuses and an upgrade to 200 amps. You likely only have 60 amps with a fused panel.

David, they're one ampere fuses, probably in the primary of a control transformer or they are the control power fuses.

Fuses provide the most accurate, dependable over current protection money can buy.

In addition fuses can provide current limiting, something circuit breakers cannot do.

They are hardly obsolete..........Regards, Rod.

[Jarrett Vibert]

Yep... fuses get a bad rap, but as Rod says, they're actually better...

It isn't uncommon in industry to see breaker protected by fuses up stream...

[Roger Bullock]

You could take it by an auto parts store, go in and say "Could you guys check to see if this fuse is good?" Chances are they will have a meter on hand and be glad to help.

[Trent Shirley]

My vote for fuses AND mult-meters
A couple years ago I was replacing my electric range. I switched off the 220 breaker at the panel and went to work.
While disconnecting the power leads from the back of the range my wrench contacted the metal of the range and threw a nice shower of sparks. I was wearing gloves and not touching the metal body of the range so I was not jolted.
Turns out one of the two 30 amp ganged breakers actually failed to disconnect power in the off position and there was still 110v going through the line.
I never touch a power line now without doing a check with my meter.


David, they're one ampere fuses, probably in the primary of a control transformer or they are the control power fuses.

Fuses provide the most accurate, dependable over current protection money can buy.

In addition fuses can provide current limiting, something circuit breakers cannot do.

They are hardly obsolete..........Regards, Rod.

[Pat Barry]

The idea with the light bulb and pigtail wire i good - just bad using your fuse box. Never ever ever do it that way. Use a flashlight battery and flashlight bulb. Safety first.

[Phil Thien]

To reply to the OP's original question, yes, it is blown.

How do I know? I don't, really. But I got a 50-50 chance. If I'm right, I'll seem brilliant.

Probably not after admitting my strategy, though.

[Clarence Miller]

Or, if you don't have a meter, you could take a 9 volt battery, and place one of each of the fuses on the battery, and the other end on your tongue. If you get zapped, the fuses are both OK.



(just joking) Why not treat yourself to a Christmas present and get a multimeter? You can spend whatever you want, and they can all check fuses.

Your sick, but I was thinking along the same lines.

I am a fan of going to the auto parts store or using a multi meter.

If you are dead set on testing it yourself use jumper cables and a car battery. hook the positive up to the fuse and battery, and the neg to the battery only. when you tap the neg cable end against the other side of the fuse and it sparks you are in business. I would recommend using your neighbor's (or some relative you don't care for) car if yours is post 1973. Such testing has been known to cause problems for electronic ignition systems.

[Jim Heffner]

By looking at them...kinda hard to tell. An ohm meter is the best test for sure.
Another method that I have found to work well is...take one of the fuses,
hold it close your ear and shake it vigorously and listen to it, if it sounds like
loose sand shifting back and forth ....it is blown. Works for me, learned that
from an old electrician when I worked with him years ago...never failed yet!

[Justin Freund]

Fuses like that are about a dollar each. Not much lost by just buying new ones. I do agree that a good multimeter is still a great tool to have.

[Phil Warnement]

A follow-up on Trent's post. A volt-ohm meter will definately find your problem. The key, however, is knowing how to use functions of the meter. If you know how to use one the check takes about 30 seconds to perform. If you don't know how to use one the results can be shocking

[Jarrett Vibert]

The key, however, is knowing how to use functions of the meter. If you know how to use one the check takes about 30 seconds to perform. If you don't know how to use one the results can be shocking

...and possibly explosive....

[steven c newman]

While you are replacing that bad fuse, go ahead and replace the rest. If one has blown, the rest will follow along, later. A set of "fresh" fuses is just good maintainence. When in doubt, throw it out. While you are at it, buy some spares, for later on.

[ray hampton]

My vote for fuses AND mult-meters
A couple years ago I was replacing my electric range. I switched off the 220 breaker at the panel and went to work.
While disconnecting the power leads from the back of the range my wrench contacted the metal of the range and threw a nice shower of sparks. I was wearing gloves and not touching the metal body of the range so I was not jolted.
Turns out one of the two 30 amp ganged breakers actually failed to disconnect power in the off position and there was still 110v going through the line.



I never touch a power line now without doing a check with my meter.
using a meter are okay but a simple circuit tester are a quicker way to test circuit

[Keith Westfall]

The key, however, is knowing how to use functions of the meter. If you know how to use one the check takes about 30 seconds to perform. If you don't know how to use one the results can be shocking

...and possibly explosive....


I need someone to explain this to me. How can using a ohm meter be shocking or explosive??

Have I just been lucky for over 30 years???

[Chuck Wintle]

I need someone to explain this to me. How can using a ohm meter be shocking or explosive??

Have I just been lucky for over 30 years???

maybe it depends where the ohmmeter probes are placed?

[steven c newman]

I had one go ZAPPP! once. I still ahd it the Ohms section, and tested some ac, live in an outlet. A nice flash from inside the case, and then the smoke rolled out. OOPS. Take the fuse out of the fuse holder, and place the fuse between the probes ends. If the scale is on the "Ohms" section, you will get either an almost zero reading ( that fuse is good) or, if the needle "pegs" at the other end of the scale (fuse is blown, buy another). A "good' fuse should show almost no resistance, while a blown fuse will show a lot of resistance.

[Jarrett Vibert]

I need someone to explain this to me. How can using a ohm meter be shocking or explosive??

Have I just been lucky for over 30 years???

lol...maybe...

Cheap multimeters that do not contain internal overcurrent protection have been known to explode, if used improperly. Usually it's case of the meter being set up to measure component amperage, but then used to check for voltage. It's really not that uncommon an occurance. In fact, I have received warnings from the ESA (canada's Electrical Saftey Authority) about Chinese made meters coming into the country with fake CSA stamps in their casings... The internal protection is one of the standards ignored by the off shore "cheapy" meter makers.

[Jim Summers]

If the scale is on the "Ohms" section, you will get either an almost zero reading ( that fuse is good) or, if the needle "pegs" at the other end of the scale (fuse is blown, buy another). A "good' fuse should show almost no resistance, while a blown fuse will show a lot of resistance.

Maybe I am mis-reading this, but, I thought when ohm'ing things if the needle moves you have continuity and hence a circuit. If the needle stays at zero, then no circuit, meaning a blown fuse. But maybe it is the type of fuse??

Thanks

[Phil Thien]

Maybe I am mis-reading this, but, I thought when ohm'ing things if the needle moves you have continuity and hence a circuit. If the needle stays at zero, then no circuit, meaning a blown fuse. But maybe it is the type of fuse??

Thanks

You are correct, if needle moves, electrons are flowing...

[Matt Meiser]

I had to take arc-flash training at my last job. They talked about numerous examples of meters exploding. There was one example where a meter case opened part way up and then closed back up with a bunch of the guys skin inside. If I recall correctly they recommended a meter marked at least Class III or maybe Class IV. They little electro-mechanical voltage testers (nicknamed "wiggy meters" around here) were outright banned in auto plants.

[Rod Sheridan]

Good point Matt, we also have to use a Cat IV 600V or Cat III 1000V meter.

Arc flash injuries aren't any fun..........Rod.

[Ken Fitzgerald]

I have to be recertified in arc flash annually and carry an arc flash kit. My rubber gloves can't be more than 1 year old....vest......helmet with shield.......leather gloves......

[Tom Esh]

I had to take arc-flash training at my last job. They talked about numerous examples of meters exploding....

Bingo Matt. That's why I won't get anywhere near mains or a panel with a cheap meter. Most injuries with MMs are not due to electrical shock, but rather burns and shrapnel. The case on a good one is essentially designed to contain a small explosion. Hard as it may be to get a Fluke to do anything but beep or blow a fuse, there's no stopping someone really determined to do something foolish.

[Sean lennon]

+1 on the use of fuses.

nothing better or more reliable.

I have seen many breakers that drift out spec after they have been tripped.

[Jarrett Vibert]

I have to be recertified in arc flash annually and carry an arc flash kit. My rubber gloves can't be more than 1 year old....vest......helmet with shield.......leather gloves......

My plant is just starting to get into compliance with arc flash regs on the floor. We've always had the suit, helmet/shield for the switch gear room though. Each electrician is issued 2 pairs of gloves. One is always out for testing, and gets swapped with the set in use when it returns.

Arc flash is serious business... Fortunately the management here force all personal to go through awareness training/scare session. It's only for those handful of weeks afterward that the operators tell me I'm worth what the company pays me.:p

[Ken Fitzgerald]

Jarrett,

You only have to see the photos of burned flesh once to be a believer. It's serious stuff.....or consider blindness....

[Jarrett Vibert]

or consider blindness....

I've been there, on temp basis mind you. Scariest 2 mins of my life... My worst at work accident by a long shot was by flash. I'd rather take a lift any day.

[Ken Fitzgerald]

Jarrett,

I became deaf in July of this year. I will be retiring shortly because of the safety and communications problems it causes. I can't talk on the phone, hear television or most peoples voices. It wasn't due to anything I did but it does make one consider safety with a different attitude.

[Jason Roehl]

Maybe I am mis-reading this, but, I thought when ohm'ing things if the needle moves you have continuity and hence a circuit. If the needle stays at zero, then no circuit, meaning a blown fuse. But maybe it is the type of fuse??

Thanks

If you have your multimeter set on resistance (Ohms), and it reads zero or very close to it, then that indicates continuity--a circuit, and the fuses would be good. A digital multimeter will show a tenth of an Ohm or so on a good fuse, and show OL (not sure--overload, out of limit or open loop) on a blown fuse.

[Phil Thien]

Could you guys versed in arc flash give those of us that aren't a little primer? At what kind of voltages/currents does this become a big concern?

[Jarrett Vibert]

To be honest, I had to google it to find real numbers. From what the great wiki tells me, systems operating below 208v phase to phase don't have enough potential to cause an arc flash. It more so the commerical/industrial systems 480v and up that it becomes a viable hazard.

Caution on the google image search if you have a weak stomach...

Not 100% on how we got into the discussion of arc flash here seeing as it really doesn't relate to the topic. However my mulitmeter warning stands...

[ray hampton]

On the multimeter that I use the needle are at rest on the left side of the meter face, a zero reading in OHMS would move the needle to the right-side of the meter face

[ray hampton]

I got a important Question for someone that have some experience with TIG welding and other HIGH Frequencies, PM me

[Jason Roehl]

I once saw a minor arc flash incident in a warehouse I was painting. One of the owners (a former electrician) was running a metal fish tape in some new, horizontal conduit on the ceiling to an open, empty junction box. Somehow, the tape, instead of coming out the open junction box, turned the corner down and went into a 3-phase panel, shorting at least one of the phases. All I saw were sparks (really, molten pieces of the fish tape) thrown out about 20+ feet. I was at least 50 feet away, and not looking directly at it, so well out of harm's way, but the noise and sparks sure got my attention! The owner was fine, too.

[Curt Harms]

I was in N. Jersey when a utility co. transformer shorted/arced/whatevered. It was bright sunny day. It got brighter when that puppy did its thing.

[Roger Bullock]

A friend of mine had a good digital multimeter set to ohms and said that when he tested his fuse, it showed that the fuse was weak. WEAK I asked, how are you testing them, a fuse is either good or bad. His reply was that he held the probes onto the fuse with both of his thumbs at the same time. The fuse was bad but it was reading continuity through his body.

An old electrician I knew upon completing a training class was asked what he had learned. His reply "Electricity.....if you don't know what your doing can kill you!" :eek: