Sunday, September 19, 2021
Sunday, September 19, 2021

RVelectricity™ – Just Ask Mike (J.A.M.): May the torque be with you…

Welcome to my J.A.M. (Just Ask Mike) Session, a weekly column where I answer your basic electrical questions. If you’re a newbie who’s never plugged in a shore power cord (or ask – what’s a shore power cord?), or wonder why your daughter’s hair dryer keeps tripping the circuit breaker, this column is for you. Send your questions to Mike Sokol at mike (at) noshockzone.org with the subject line – JAM. This week I discuss torque and torque screwdrivers.


Dear Mike,
I really liked the “Mike’s Gadget” Torque Screwdriver in your RVelectricity™ Newsletter last week, but I can’t find a chart showing proper torque values. Please help!!! —Larry the DIY Guy

Dear Larry the DIY Guy,
I’m so glad you’re taking this problem seriously. I get email every week from readers who have burned up Generator Transfer Switches and Shore Power Plugs. One thing to remind you is to make sure ALL power is off. So unplug from shore power, turn off your generator, and power off your inverter.

Safety First!

But first, make sure there’s no possibility of 120-volt power. And if you’re going to re-torque any of your 12-volt DC screws, be sure to disconnect the batteries so you can’t create a shore circuit and melt a wrench, or get your wedding ring or metal bracelet trapped in the fault current path.

What are the numbers?

Just remember these are all in inch-lbs of torque, NOT foot-lbs like your wheel lugs. You’ll want a torque-limiting screwdriver that can be set from 20 in-lbs to 60 in-lbs, and have the proper bits for each type of screw you need to re-torque. Also, back off each screw a little, and then retighten them until the torque screwdriver clicks. You can get this torque screwdriver on Amazon HERE.

Loosen the torque driver when you’re done

After you’ve finished your yearly re-torque maintenance, you’ll want to back off the torque setting on the screwdriver to as low as it will go. This will prevent accuracy drift from the spring being under tension for months at a time.

Chart 1 on WFCO power centers

Chart 2 on standard circuit breakers

Chart 3 on a Southwire Generator Transfer Switch

That’s a wrap!

OK, everyone. Remember that electricity is a useful and powerful force, so we all need to pay attention to safety precautions while using it.

Let’s play (and stay) safe out there….

Mike Sokol is an electrical and professional sound expert with 50+ years in the industry. His excellent book RV Electrical Safety is available at Amazon.com. For more info on Mike’s qualifications as an electrical expert, click here.
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And you don’t want to miss Mike’s webcasts on his YouTube channel.

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Thomas D
12 days ago

Interesting article, but it’s been a while since I’ve read the NEC. I don’t remember ever reading about torquing terminals. Has that changed? (Retired for 12 years)
If I were still working, I’d buy one of those. Good idea.

Mike Sokol
12 days ago
Reply to  Thomas D

Every listed connector has a torque requirement included in their installation documents.

David Telenko
12 days ago

Looks like a great tool. Wondering if it comes with a certified torque calibration? I have a buddy electrical contractor who was getting an inspection & was asked what were torques on the service panel screws. Well they are tight, the inspector said they need to be torqued to the proper specs. My buddy went out & bought the necessary torque wrench. The inspector came back & saw the tool & then asked for the calibration certification date for the tool! True story!
Snoopy

David Telenko
12 days ago
Reply to  David Telenko

Ok just re read the specs & indeed it does come with one. “Each Shipped Wrench Units Includes A Calibration Certificate of Conformance in Accordance with ISO 6789-1:2017”.
Snoopy

Dan
12 days ago

Great article. Much, much better than the usual instructions to “not overtighten”.

Stephen Malochleb
12 days ago

You’re articles are so (electrifying). Thanks for the info.

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