Question for the tractor electricians

[RFB]

I have an Kubota L5030HSTC.

It has four 27watt work lights (2 front/2 rear) on a single 15 Amp fused circuit.
(There is only one 15 Amp fuse in the block that is marked as the position for "Work Lights".)

I want to change those lights out for four 50 watt work lights, which will exceed the circuit rating by about 1.6 amps. (16.6 amps on a 15 amp circuit)

If I were to replace the 15amp fuse with a 20 amp fuse, that would solve the first step.

The real question is: Is that extra 1.6amps significant enough to seriously overload the circuit wiring?

 

[bigdad]

That's a good sized Kubota, do those big ones have a big enough alternator to handle the increased load? I would worry about that before the wire size.

 

[kennyd]

No way would I do that! You have no idea what the switch is rated for, or the plugs in the harness's, or the sockets, or even the gauge of all the wiring feeding the light circuits

 

[RFB]

bigdad: The 60 amp alternator will handle the output.

kennyd:

With all due respect since I did ask the question, but I do know what the rating is on all of those components: 14.99 amps. Otherwise it would not be fused at 15 Amps.

My question is, from an electrical engineering standpoint, whether or not an additional 1.6 amps is beyond the capacity of those components, excepting the fuse itself?

Pertinent to the question is also the fact that the additional 1.6 amps is distributed between 2 different switches and circuits, coming into one fuse block location, so each switch/light circuit is only seeing an additional .61 amps beyond rated capacity based up[on a 15 amp fusing.

The original lamps are 27 watt which equals 2.25 watts. (50 watts at 12 volts equals 4.16 amps). Nonetheless, the circuit is fused at 15 amps, so that must mean that amperages below 15 are "safe". Is an additional 1.6 amps pushing the components too far.

 

[kennyd]

If you plug a heater into an outlet in your house-and it pops a circuit breaker, Would you install the next higher rated breaker to solve the problem?

When doing your calculations for current draw, use 13.8 volts instead of 12 volts. That is the approximate voltage the alternator puts out the charge the battery.


Edit: Changed 3.8 volts to 13.8 volts

 

[RFB]

keenyd,

Are you saying that my 60 amp alternator will not (through the voltage regulator) charge the battery at a level higher than 3.8 volts?

 

[SPYDERLK]

keenyd,

Are you saying that my 60 amp alternator will not (through the voltage regulator) charge the battery at a level higher than 3.8 volts?

He meant 13.8. I think you will have no trouble with the slight overload. Where it will show up 1st if it shows at all will be connectors or switches. If resistance develops at a such a contact/connection the higher load will cause heating to be more critical.
larry

 

[RFB]

From the engineering standpoint, I was using 12 as the conservative figure and hoping for the 13.8 for even a little more flexibility.

His 3.8 confused me so I started searching for battery charging capacity and came up empty. (My traditional knowledge was 13.8.)

The switches themselves will realistically see only a about a 1.7 amp increase going from the 27 to the 50 watt lamps. (2 switches/4 lamps)

Thanks

 

[mjncad]

RFB:

What gauge wire is used in your rig's lighting circuit? Are the lights run directly through the switch, or through a relay, which is common practice for automotive lighting circuits such as headlights and work-lights.

My concern in your case is switch rating, existing wire gauge and condition, and length of wire run that could result in excessive voltage drop.

I just tested out my latest wiring and lighting modifications today, and I ran all my lights through relays where 18 gauge wire from the switch activates the relay's coil. The wire from the relay to the lights is 14 gauge. The lights I bought appear to have come with 18 gauge pigtails. It would have been easier, simpler and involved less wire to eliminate the relays; but since relays are accepted practice, who am I to argue with those who went before me.

Although I special ordered my tractor, I can't remember if I ordered the extra capacity alternator or not and my sales paper work doesn't list the options I ordered, just the tractor and implements. I looked at the Denso alternator's rating plate today, and no where to be found was an amp rating, unless it is buried in manufacturer's code; however the voltage rating was readily apparent. I have a hunch an alternator will be on the project list.

 

[mopacman]

I think I would try it on the 15 amp fuse first it might work, then go to the 20 amp fuse. The only time I have had trouble with switches is when I have gone from 2 bulbs to 6 bulbs. I think the switches will be the week link. If you deside to change wiring I would go to a relay system and use the switches and wire you have now to operate the relays and add a new circuit for the lights but I dont think you will need it......Larry

 

[bigdad]

Somewhat relevant...... what about LED lights for these work lights? I use them in flashlights etc. with great results and low current draw. Anything like that available?

 

[SPYDERLK]

From the engineering standpoint, I was using 12 as the conservative figure and hoping for the 13.8 for even a little more flexibility.

The switches themselves will realistically see only a about a 1.7 amp increase going from the 27 to the 50 watt lamps. (2 switches/4 lamps)
Thanks

My interpretation says each light draws 1.9A more. With 2 lamps per switch that adds 3.8A per switch. With both front and back lit the main circuit draw will increase 7.6A. You will want to be sure to check connectors and switches for warming. Youre increasing load by 85%. Even if it works fine, spot check for heat occasionaly. Connections/contacts can degrade, and once significant heating starts degradation will accelerate - so any indication will need prompt attention to renewgood contact.
larry

 

[bjcsc]

My thinking is along the same lines as mopacman. The way I figure it, using 13.8V, you going from a 7.8A draw to a 14.5A draw. How many switches are there? 2? Do you intend to change the light fixtures themselves or are you trying to just use higher wattage bulbs? If you're changing the fixtures, and you wire them (or they are already wired) with the appropriate gauge wire (don't know what you have running to your current fixtures), the switches could be your weak link. So as mopacman mentioned, you use the switches to trigger 2 separate relays that are common fed from the current fuse for your worklights. If the 15A fuse blows (I don't think it will), instead of using a 20A fuse in that location, I would simply run a new common feed wire (correct gauge) from the battery to the relays with an inline 20A fuse.

 

[RFB]

Thank you for all the counsel. I will try the 15 Amp fuse first.

The wiring is all completely run by the factory in the L5030 cab tractor, and is stubbed out to the work light locations with bullet-type connectors. The tractor comes with front work lights, the rears are options but are "plug-n-play". The installation requires cab roof removal only to plug the switch into existing connectors, and all of the wiring is complete in factory runs and bundles. I installed the factory rear lights last year, and was completely underwhelmed by the performance of fronts and rears over this winter: 27 watts of not very bright light from a fairly chintzy lamp assembly using back-up bulbs as the source. (I tried some "super-bright" 35 watt back-ups but they failed in a few hours, and produced little discernible improvement.)

The Kubota switch part numbers for front and rear respectively are T1065-75360 and T1065-75370.

I have zero knowledge regarding their ampacity.

I have attached pdf's of the parts manual detail, but it really gives little information.

bjsc,

There are 2 switches and 4 lights, (1 switch front, 1 for rear). I am planning on new light assemblies.

 

[DRL]

If you have two switches being feed by one 15amp fuse, each switch still has to be rated at least 15 amp, but only has two of the lights drawing from it. I don't think the switches or wiring down stream from them will be a problem. The only thing you are getting close to pushing the limit on is the fuse and wiring before it spits in two for the switches(14.5 volts as said earlier). Worst case you will need to spit the feeds for the switches and feed each one with its own 15amp fuse. Should be easy with an inline fuse holder.
DRL

 

[RFB]

Thanks for the input...the hardest problem is finding the raceway for the existing bundles/runs.

 

[bjcsc]

Once you determine the gauge of the factory wiring and the approximate length of the runs, you can use this calculator to see what you'll get (voltage) at the light fixtures. I would think that the factory wiring would support the upgrade, but only you know the gauge of the wire they use.

I don't see how the switches can be assumed to be rated for 15A when the load they handle (at 27w) is less than 5A, unless DRL knows that Kubota runs those switches in series. That would be another clue...if the switches are the same and in series then they will be each rated for 15A (and you could use them as is), but if they're parallel they could be rated as low as 5A in which case you go to relays.

If you split the feeds after the 15A fuse per DRL's suggestion (again, this assumes they are in series to begin with) I don't see the point of running a redundant inline 15A fuse on each feed. If they are in series, the wiring is rated for 15A, and protected by the 15A fuse that it is currently using...

 

[RFB]

bjcsc,

I am committed to making the change because the existing lights are useless ornaments. I have not yet selected replacement lights, and in this area, Kubota's quality is shoddy. These lights are cheap plastic housings, plastichrome reflectors, and 27 watt (1156) backup bulbs, for the princely sum of $50 each. They are not worth $10.

If I have to use relays, do you have a suggested type/model and vendor?

 

[texbaylea]

Has anyone compared the multi-led replacement bulbs for brightness against the incandescent bulbs? If they are brighter then that is a no-brainer upgrade with lower draw.

Vernon

 

[RFB]

texbaylea,

You are right on that, but due to the prices I did not want to do my first knee surgery on my knee.