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If I want to add a torque driver to my toolbox, so I can improve the quality of DIY electrical work in my home, what is a suitable torque range and precision I should look for? It should be suitable for use with breakers, panel buses, outlets, and switches with copper wire from #14 to #10. Assuming no prior knowledge of what devices, from what manufacturer, I might buy in future ... what is a reasonable range of torques that ought to cover these needs and how precise does the driver need to be?

Also, I believe a screwdriver with a straight or T handle would be more convenient to use than a wrench-style driver because they are easier to to use single-handed. For the kinds of projects a homeowner would DIY, for working on screws inside boxes or dangling from boxes with the noted wire sizes, I think single-handed is an advantage. Any advice on that?

jay613
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  • Is this for a mountaineering RV or something? – dandavis Sep 29 '21 at 19:37
  • I think most electrical torque values are in inch-pounds more than foot-pounds, so a 3/8 inch torque wrench would be best size. – crip659 Sep 29 '21 at 19:38
  • @dandavis not sure what you mean. As stated, the question is about a home. It is not about an RV, although if an RV had electrical connections designed to be precisely torqued, I hope this question would help there too. – jay613 Sep 29 '21 at 20:20
  • @crip659 I would think a screwdriver-shaped device would be easier to use than a wrench, but I'll add that to the question. – jay613 Sep 29 '21 at 20:21
  • Most torque wrenches are ratchet style so extensions can be used. If there are screwdriver types around, would think they would be very expensive type, much more than a DIYer could afford. A torque wrench usually uses the length of the handle in setting torque value. – crip659 Sep 29 '21 at 20:36
  • That's been vexing me, since I'm doing a lot of fasteners (6mm on a car) that want 12-18 ft-lb. I prefer beam-type torque wrenches, they are cheaper and don't lose calibration. And all the small ones stop at 100 inch-pounds (8 ft-lb), bad for me but perfect for electrical. – Harper - Reinstate Monica Sep 29 '21 at 20:48
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    @crip659 What you don't know is that NEC 110.14 was added in 2014. It requires electricians use torque drivers to set screw torques on receptacles, switches and darn near everything - jobs previously done with hand screwdrivers at wildly varying torques, it turned out. Causing copper connections to fail the same way those infamous small aluminum wires were failing, imagine that! So the edict went down, and suddenly a heinously obscure product - the torque screwdriver - became available at every electrical supply. No one has apologized to aluminum. – Harper - Reinstate Monica Sep 29 '21 at 20:51
  • @Harper-ReinstateMonica I learn something new everyday on here. Did not know of torque screwdrivers. Thank you. – crip659 Sep 29 '21 at 20:59
  • What I did not know is that this was ever not the situation. :). The only torque wrench I ever bought was for tires, and for that you HAVE to use a wrench. A long one. Now I'm looking for electric I just see a huge selection of styles, torque ranges and prices. I'm pretty sure I want a screwdriver, because I can't imagine torquing a receptacle with a wrench with just two hands. So I just need to get an appropriate torque range. – jay613 Sep 29 '21 at 21:02
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    One opinion: I got a 10-50 inch-pound screwdriver model (Wiha), and it covers a lot: ordinary breakers, alumiconn connectors, receptacles. It won’t do bigger lugs on panels. Check your use cases. – Aloysius Defenestrate Sep 29 '21 at 21:14
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    Here is a little data. Not enough to make an answer, but aligns with suggestion in above comment. Leviton receptacles residential 9 to 14 inch pounds, commercial up to 20. Hubble 9 to 12. QO breakers up to 100A, 25 to 50 inch pounds. 10 to 50 and 10 to 70 seem to be common ranges available. It would be nice to know if there are other breakers requiring say 90 inch pounds that I might discover in my next home. – jay613 Sep 29 '21 at 22:07
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    @Harper - Reinstate Monica -- Dear Aluminum: I'm sorry I blamed you for all those connection failures. I promise not to do that again. For my penance I am now using a torque screwdriver for everything. Sincerely, The National Fire Protection Association – A. I. Breveleri Sep 29 '21 at 22:45

2 Answers2

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For normal residential work I'd suggest a torque screwdriver with a range of 5 to 60 in-lbs . That should cover your switches,outlets and circuit breakers which have an approximate range of 9 to 14 in-lbs. For main lugs in panels, you'll need to torque to about 250 in-lb or a 20 ft-lb so a wrench in the range of 0-30 ft-lbs would be needed with hex fittings. I like the types that click when the set value is reached. The actual torque values are stated on the labels of the equipment you'd be working on.

JACK
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    Yeah, starting at 5 in-lbs is best because torque tools (screwdrivers & wrenches) tend to be a bit inaccurate at the low end of their range – ThreePhaseEel Sep 30 '21 at 00:59
  • This is good advice and I think it very pointedly answers my question! I do not, however, think I will follow it exactly. There are lots of well-priced drivers with 10-50 or 10-70 ranges. I think I'll buy one of those for the reasons in this answer. Getting down to 5 means either buying second one or buying a very expensive one. I would cross that bridge when I come to it. As for main lugs, I don't see myself doing a project like that without at least some professional involvement ... and if I did, I could probably use my tire wrench, I think it's in range. – jay613 Sep 30 '21 at 12:18
  • 250? Really? How do you manage that? My tire wrench maxes out at 150! And to get more than about 100 I have to stand on the 24 inch wrench. I haven't seen main lugs being tightened but how do you get that much torque? A 4 foot wrench? How do you not tear the panel off the wall? – jay613 Sep 30 '21 at 12:24
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    @jay613 250 in-lbs,, not ft-lb. If your tires are torqued at 250 in-lbs, please don't ever offer to drive me somewhere... lol. Check your wrench again with glasses on. – JACK Sep 30 '21 at 12:30
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    Use care when reviewing specs, @jay613. I just discovered this one that is rated in inch-ounces, not inch-pounds! Of course, the price will probably scare most casual DIYers away. ouch – FreeMan Sep 30 '21 at 13:40
  • Yeesh, that said, most of these are pretty spendy little devices. Cheaper than burning down your house, though. I'm guessing that the more words in the product name indicating "precision" and "accurate", the less likely it is to be true... :( – FreeMan Sep 30 '21 at 13:45
  • @FreeMan Yes!!! spendy little suckers.... probably why I got laughed at when I'd pull one out and quit following the "quarter turn past snug" . – JACK Sep 30 '21 at 14:01
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Simple is good. There are torque wrenches that have a fixed nominal setting, and if you're always working on the same values, then a hard-configured tool is one less thing to get wrong.

Downside of these is you need one for each torque setting you intend to use - if a fastener needs a higher torque you either need a larger one, an adjustable one, or "add some more torque" with a spanner/driver.

You can't just "lean on these harder" to go beyond the fixed setting.

Example, (from the cycling world) This one is 4Nm which is ~35 inch pounds: ""

Criggie
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    Note the question .. I want to buy one device that will allow me to handle various unpredictable tasks that fall within a predictable range. A preset device does not meet that criteria at all. I would have to wait til the next project, find out what I need, then go out and buy that precise wrench ... and what would probably happen in that scenario, I would just do without it, as I always have. – jay613 Sep 30 '21 at 12:30
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    Also, at $40 per wrench (as of today at Park Tool's web site), that's a bit ouch. Plus they've only got 4, 5 & 6 NM wrenches - even if you splash out for the full set, it doesn't give you many options outside the cycling world. – FreeMan Sep 30 '21 at 13:37
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    And note to others: The king of "cheap", Amazon.com, has these exact same Park Tool wrenches for 50% more than you can get them direct from Park! – FreeMan Sep 30 '21 at 13:47
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    Some bike jobs require special tools, like a pedal or cartridge wrench. I love Park Tools for those things, they are great and affordable and make it easier for DIYers to bite off more. Even then, however, I wouldn't by three separate $40 wrenches unless I had a repair shop with at least two mechanics working full time. – jay613 Sep 30 '21 at 16:33
  • *** The point of this was a driver with a single pre-set value. If you're doing a job then there will be many fasteners of the same type and therefore torque value. By not having an adjustment, the risk of error is reduced. – Criggie Sep 30 '21 at 18:43
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    Since the original question is electrical work, can I assume that torque drivers designed for cycling are likely suitable for electrical work? They seem to be ~1/2-1/4 of the price of those sold as electrical tools. – Michael Mior Sep 15 '23 at 15:44
  • @MichaelMior torque is torque - the only potential issue I see is whether an electrician's tool needs to be calibrated for accuracy for legal liability reasons. – Criggie Sep 15 '23 at 21:29
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    @Criggie I get that torque is torque. I was mostly just wondering if it's reasonable to expect such tools to be appropriately calibrated. – Michael Mior Sep 17 '23 at 12:25