12 V 30 amp supply from L6060 to sander?
- Thread starter Gaspasser
- Start date
That is correct. In this case, even if the OP took the wire on the scenic route an assumption that a 40 foot round trip for the electrons would cover it. A full 1,000 feet run of #10 has roughly one ohm of resistance. #8 and #6 have 0.64 ohms and 0.4.
Working with roundish numbers #10 would lose 1.2V and #8 would drop .77V. Most of what I've read puts these voltage drops within an acceptable range. Some sources indicate even lower voltages can be OK.
Explaining and putting electrical theory on paper is above my pay grade so I must defer to past experience and observations. Lights,resistance heat and some other applications seem to tolerate voltage drop without lasting consequence. Motors, particularly those under load overheat and eventually fail. An application most of us are familiar with is starters. A fully charged,healthy 12v battery has 12.7v. Reduced by 1.2v leaves 11.5v which isn't enough to click, much less run starter.
Yup.
The issue running 'just enough' for any motor is starting draw is often massive. Total load is watts, Volts X Amps. Lower volts needs more amps, a heavier load on the wiring. Even if only for a few seconds. Lighting loads, the surge is so fast as to rarely be a problem.
I was schooled, see/calculate what it needs and leave yourself at least a 20% headroom.
I've never had an issue where the wire was too oversized, only when too undersized.
Skip to Item #2. Whether it would slow the motor noticeably, I wouldn't know but doubt it
tsinglinmotor.com
How to Slow Down a 12 Volt DC Motor - TSL Motor
A 12V DC motor is commonly used in industrial, automotive, and consumer electronics applications. However, in some cases, the motor might be spinning too fast
tsinglinmotor.com
Any starter will run just fine at 11.5V. When cold cranking even a good battery drops to 5 Volt with the solenoid engaged and the starter turning. With severe cold the voltage can drop briefly even to 3V.
Had my starter out two days ago and could have measured at what voltage the solenoid still engages.
so... #10 is about 1 ohm per 1,000 ft. Say you use 10'. It'll be about .010 ohm . V=I * R , 30 x .01=.3 volt drop.
Now X2 that ( 2 wires ! ) so .6 volt drop. Not a big deal.
Now X2 that ( 2 wires ! ) so .6 volt drop. Not a big deal.
A starter requires a wee bit more than 30 amps.
And THAT makes all the difference. You cannot choose an appropriate wire gauge without knowing the required current draw and the distance.
I've always thought most starters require more than 30 amps and that load must be known in order to choose appropriate wire gauge. Thank you for the reaffirmation.
Ampacity isnt always a cut and dried hard rule. For example when I built my shop i had the POCO upgrade my 200A residential service to 400A and double lugged the meter base for two separate 200A service entrance panels. The service entrance cables were 4/0 aluminum per the NEC. The NEC also requires minimum of 750 Kcmil aluminum for 400A service but the POCO said the existing 200' of 4/0 direct burial aluminum from transformer to 400A meter base was just fine and NEC did not apply. The local authority agreed.
Dan
Dan
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Yeah - pretty sketchy looking crew....What else would you expect from and outfit named POCO than very little or somewhat?
Dan
OK, finally have a few days off to wire the sander as in originally posted question. Occurs to me that rear window defroster (L6060 cab) is wired with wiring and fuse for 40 amp capacity. I'd only need about 5 feet additional wiring from defroster wires to sander via a rubber diaphragm plug in rear of cab. I could splice into the defroster wires with a switch that energizes either the defroster or the sander (only one at a time) with a 30 amp fuse in the sander circuit as specified by Fisher. The connectors at the defroster are standard spade and lug connectors. This would allow me to avoid running a longer, separate circuit all the way from the battery. Anyone see any downside or pitfalls in this approach? Thanks as always. Happy New Year!
Attachments
should work fine, a 'yellow' spade lug will be needed. yellow denote 10ga wire. Blue is 12-14, Red is 16-18.
Just be sure to properly crimp them and tape ! tape to keep from 'zaps' AND secure them so they don't fall out and ZZZZZAP !!
Just be sure to properly crimp them and tape ! tape to keep from 'zaps' AND secure them so they don't fall out and ZZZZZAP !!
Thanks Green. Looking for 40 amp single pole double throw middle position off switch. Silicone 8 awg wire for outside wiring. Found some stuff on Amazon. Will visit auto and/or electrical stores Friday. Always prefer to see/feel stuff I buy as Amazon can be a crap shoot. Will get anderson connectors for outside connection to 7 pin adapter on sander. I should go into the connector business. Lol. Happy New Year.
You'd be better off with a regular 12V toggle switch switching a 40A SPDT relay.
Ty Dustball. Been a while but wouldn't relay require an independent line to activate relay and the 2nd circuit which is being controlled? If you know of an example, I'd appreciate the heads up. Thanks.
Yes, it would. But you would not have to run a fat 40A cable up to the dashboard where a bulky 40A switch is sitting. The relay control could come from another ignition circuit with a much lower fuse rating and hence thinner cables.
Here's how I'd do it. The new switch would be switching ground, just like the existing defogger relay is. The output terminal from the existing defogger relay would be rerouted through the new relay along with the new circuit for the motor. It's important that the positive source for the relay coil is ignition switched so you're not powering the coil relay when the ignition's off and you forget about it.
You could put the new relay next to the existing defogger relay (located in the engine compartment on the firewall) and work with the R/W and Y/B wires there.