Multimeters and where to buy? - Page 1
Forum section: electronics / beginners

author: vismund624
author_rank: Newbie
timestamp: March 20, 2011, 03:44:33 pm
content: Hey,I have been researching multimeters b/c I see it as the next purchase I need as a grip/electrician for film in the us when I stumbled across the youtube account for this blog. I am looking for a nice accurate hand-held auto-ranging multimeter for film (mostly Id use it for amperage and voltage AC and DC). Honestly I'd like to be able to look at and possibly hold these meters before purchasing which is why I haven't just bought a fluke online yet, but I really am at a loss for where to go. At my local home depot and lowes hardware stores all they have are Klein/Ryobi/Milwalkee multimeters which are tool manufacturers (not really electronics makers) and microcenter by me only has cheapo crap meters.My main purpose for this meter would be to measure current from mains to help determining which outlets are on different circuits in a house, measuring after dimming so I can have an idea of how many amps we are still drawing, DC/voltage for battery life for film cameras which don't have a digital reading for the battery life and currant after supposedly pure sine wave inverters for anti flicker purposes for florescent and HMI lighting. I was leaning towards the Agilent with the OLED display until I saw that review because I would absolutely need to be able to use this meter outdoors. Now I am still stuck between the cheaper agilent 1241, the fluke 87V or the drantech (but that is a little too expensive for me). Also there is a tool truck by me (b/c my uncle is a mechanic) for Snap On which also has a multimeter around the same price range but its nice because I can see and feel it in person.I am about a half an hour outside New York City, so if anyone can point me to a store where I can see these meters in person or has a recommendation for me itd be much appreciative. Also I noticed that most of the meters I've looked at have been rated as 10A max, if someone can point me in the direction of a 20 or 30A meter it'd be really nice.

author: Simon
author_rank: Unknown
timestamp: March 20, 2011, 03:53:18 pm
content: so where do you live ?

author: Unknown
author_rank: Unknown
timestamp: March 20, 2011, 04:45:07 pm
content: Quote from: Simon on March 20, 2011, 03:53:18 pmDo you have trouble reading or did someone edit their post?Quote from: vismund624 on March 20, 2011, 03:44:33 pmDon't you need a clamp meter for this? I would consider it quite inconvenient to have to cut mains wires to be able to measure current. Note that a clamp meter needs to be clipped around a single neutral/live conductor, not both at the same time, so you can't just clip it around a power cord and expect meaningful results.Quote from: vismund624 on March 20, 2011, 03:44:33 pmIf you want to judge the output of an inverter, something like a power quality analyzer or handheld scope would seem like a more suitable tool. A DMM will just tell you RMS voltage/current.Quote from: vismund624 on March 20, 2011, 03:44:33 pmSomeone living near NYC may be able to help you. You could also try asking Fluke/Agilent for any distributors in that area.Quote from: vismund624 on March 20, 2011, 03:44:33 pmSome cheap (unfused) meters are rated for 20A for a short time (some Flukes allow a 20A overload for 30s, but I don't think they will display anything except OL), but 10A is usually the limit. Above that, use external shunts (better cooling) or clamp meters. If it's just for AC current, a clamp meter may be a better tool, since you don't have to break the circuit to insert your meter. AC+DC clamp meters tend to be more expensive, but it doesn't sound like you need >10A DC.

author: Simon
author_rank: Unknown
timestamp: March 20, 2011, 05:53:08 pm
content: Quote from: alm on March 20, 2011, 04:45:07 pmI didn't get down that far. the initial question was where to find a physical store. Not knowing what stores carry I'd just advise the OP to go to the store based on their location.

author: vismund624
author_rank: Newbie
timestamp: March 20, 2011, 07:27:20 pm
content: Hey Simon. Sorry my original post was a bit longwindedThanks alm for the time in reading my post and responding. I am very new to this sort of thing and a lot of the equipment you mention I hadn't even heard about. I have to do more research about hand held scopes and power quality analyzers. What little investigation I've done so far seems like these are a little out of my league in both price and skillset. I didn't really have any schooling in electronics, the stuff I do is more about the safety of physically rigging the lights but knowing how to properly power all the different types safely is the next step and it can be very basic, but at times it can be very complicated as well.QuoteYes eventually I will need a clamp meter as well, but I would use the multimeter before connecting the mains to check which outlets are on the same circuit in the same or adjacent rooms when using house power for example.As for separating the neutral and hots how would you suggest doing that without opening the cables because I cant just do that on rented equipment? I suppose I could make my own mini-20A rated extension cord but it seems impractical to make and carry around a whole bunch of them.QuoteHey wow I cant believe I didn't even think of googling the distributors for these companies. There's like 4 stores within 5 miles of my house that are distributors for fluke. Thank you!

author: Unknown
author_rank: Unknown
timestamp: March 20, 2011, 07:44:29 pm
content: Quote from: vismund624 on March 20, 2011, 07:27:20 pmYes, they're expensive and much more complex than a DMM, but they will give you useful information about the output of an inverter, like how close it is to a pure sine wave (power factor, distortion). I'm not sure how useful a DMM will be for this, at best it will show if the voltage is close to 120V and if the frequency is about 60Hz, but not if it's a square wave (sorry, modified sine) or sine.Quote from: vismund624 on March 20, 2011, 07:27:20 pmHow would you measure that? You can measure if they're on the same phase by measuring voltage between them, but in that case you'd be measuring voltage, not current. The only way I see of verifying if they're on the same circuit is loading them until the breaker trips, and testing if the other outlet is also without power.The reason why I mention clamp meters is that some clamp meters have also some limited voltage/resistance measurement features, so it might save you from buying a DMM.Quote from: vismund624 on March 20, 2011, 07:27:20 pmYes, you will need some sort of extension cord / adapter. Note that for a DMM, you need something similar, since you have to put the meter in series with one of the live/neutral wires, which is much harder to do safely.

author: PetrosA
author_rank: Frequent Contributor
timestamp: March 20, 2011, 08:14:31 pm
content: Sears carries some Fluke meters but Grainger will probably have the largest selection of them locally. Agilent will probably not be in stock at Grainger, but they carry them, so either order or online (online is basically the main way I know of to get them).From reading your post, I recommend a clamp meter. You can't measure current in mains voltage without one unless you take the cords or plugs apart which will waste a LOT of time. The U121xA or 33X series from Fluke would both be good options. There are line splitters available for a few dollars that you can plug into an outlet that allow you to use a clamp meter to measure how much current a cord connected appliance is using and have hole for test probes so you can measure voltage as well.http://prostores2.carrierzone.com/servlet/aemc/-strse-674/Line-Splitter-Model-ALS-dsh-1/DetailI'm hoping you misused the word "current" when talking about measuring at outlets in a house to determine what branch circuits they were on and how much you have left. The only current you'll measure at an outlet is the flash-bang typeIf you need to measure the current draw on a given circuit, you need to do that at the main panel (or sub-panel - wherever the circuit originates). If you just want to measure the load, the line splitter will allow you to do that. If you don't have a thorough understand of what you're measuring, you need to get some education in the matter. Not doing so will possibly create hazards to yourself, others and equipment and will certainly cause unnecessary downtime for the rest of the crew.

author: vismund624
author_rank: Newbie
timestamp: March 20, 2011, 08:22:52 pm
content: QuoteFrom my experience outlets on the same circuit would have the same voltage, outlets on separate circuits have slightly different voltages. Whether or not its always true I'm not sure, but my friend who has been in the biz for quite some time has shown me using his multimeter how he does it without having to trip the breaker.

author: vismund624
author_rank: Newbie
timestamp: March 20, 2011, 08:35:17 pm
content: Hello Petros, thanks for your responseQuoteYes I meant voltage.And you're right I do need more education, But I definitely wouldn't do anything alone I wasn't confident I had done before. Especially when it comes to things like tying into mains and such.

author: PetrosA
author_rank: Frequent Contributor
timestamp: March 21, 2011, 12:03:13 pm
content: Quote from: vismund624 on March 20, 2011, 08:22:52 pmIt won't always be true, in fact, it will rarely be true. In most residential, there is one 240V split phase coming in on two 120V legs to ground. In a residential panel, every other breaker (counting vertically) will be on the same phase, as will opposing breakers and will read close to zero volts between them and voltage to ground will be within ~1-3V depending on a lot of variables. Full breakers next to each other (not twins) will be on opposite legs and will have ~240V between them. Both legs can have very similar voltages as well and the voltage can change faster than you can switch your probes, so you never really know unless you have two voltmeters connected at the same time. To complicate matters more, because length of wire and the resistance of splices and device connections influences voltage drop, two outlets on the same circuit can have different voltages as well. Generally speaking, the larger the voltage between neutral and ground, the further you are from the main panel.If you have large lighting loads to connect, knowing where to pull power from will be your first step. In most houses you can be somewhat confident that there will be 20A receptacle circuits in bathrooms, laundry rooms, kitchens and dining rooms (this will depend on the age of the house though). You should assume that all other receptacles will be attached to general 15A lighting circuits.