Circuit Breakers/Fuses

Ron Earp · 02-25-07, 08:40 AM

Work again has started on the Lola after a five month break with the race cars etc. Fitting the nose area where I left off and doing wiring.

I'll be making an electrical panel for the car that will contain all the operating switches for the spartan system the car will use. I've got the fuse block and harness that RCR supplies with the car and it is fine. However, I'm considering using part of it and doing away with the fuse block and using circuit breakers instead.

I could use these style breakers that are push in / pop out like on the aircraft our club has. They look like the first photo. You can get them in all sorts of amperages and just like a fuse they have just two simple connections - supply and load. I'll use the "standard" race car toggle switch to operate my circuits, the good only stainless steel switch you see everywhere.

Or, alternatively, I found these cool integrated switch/circuit breakers that are also available in various ratings. These apparently flip when tripped and you can reset them by cycling them. They are rated for circuit breaker and switch duty, sort of pricey but they kill two birds with one stone.

Anyone fooled around with either one?

Lynn · 02-25-07, 11:05 AM

Ron,

I really like the idea of circuit breakers for a race car with immediate reset capability. Being a pilot also, my prefereance would be the push/pull types, which also present far less (if not nearly impossible) chance of accidentally flipping them off.

One thing I might suggest which will have to be weighed against the KISS principal is this: control your high amp runs with relays (high quality of course) to keep those runs as short and direct as possible. Then control the relays with very low amperage switches on the dash. Simple fuses will suffice for the low amp switch circuits because, barring a dead short, they are very unlikely to be blowing fuses. The trick then is to mount your breakers where they are reachable, for mid race reset, while maintaining the directness of you higher amp circuits.

This will reduce line loss in your higher amp circuits and I think it would increase safety by having less higher amp carrying wire exposed to damage.

Lynn

Big-Foot · 02-25-07, 12:03 PM

Ron - I've used the push on/off circuit breaker that you show above.
A great place to buy these components and all other manner of electrical supplies and tools is Waytek. Reasonably priced and very prompt.

Waytek Wire : Electrical Wiring Supplies & Industrial Products

Malcolm · 02-25-07, 12:27 PM

Ron

I used the top type switch/fuse in the pitcures above when racing the 993. Seemed good then so should be a good idea for the lola.

Sandy · 02-25-07, 01:07 PM

I have use the Aircraft Push/Pulls and they are very good. I got them from aircraft spruce, I think much nicer made. They were made by Klixon 7277 series and are small. Nice looking button head as well. I'm not sure which ones I got, but they have some in the 16 dollar range which is less than what I got them for a few years back.

Circuit Breakers from Aircraft Spruce

A shot (fuzzy) of the cobra dash with them on a panel.

http://www.geocities.com/sganz.geo/cobra/dashfar.html

Sandy

SpyderMike · 02-25-07, 03:05 PM

on the flip side, I like fuses. I built my plane with fuses. One thing you don't necesarily want to do is reset a tripped breaker. You may make a bad situation worse. It trips for a reason. Pull over (or land) and find out why.

Oh, plus they are cheaper, more reliable, just about as easy to replace as it is to reste a breaker, they are lighter and you can get them anywhere.

Just my opinion.

Mike

Ron Earp · 02-25-07, 03:38 PM

I like the breakers in the planes, however, I also agree with you on finding the issue and would do so regardless of fuse or breaker. But sometime you know the issue or caused the problem. Once at the track last year I acidentially shorted Jeff's TR8 and blew the fuse for the starter 5 minutes before call to grid. I sure would have liked to have had a breaker to reset there.

Ross Nicol · 02-25-07, 06:42 PM

Like Mike I'm a fuse man for the following reasons.
1/ As Mike says a fuse blows for a reason.
2/ When you look at a blown fuse it can indicate whether it was overloaded or the circuit is shorted.
An overload will melt the fuse and normally leave blobs on the end of the wire.A short circuit normally sprays copper and leaves a black carbon deposit around the glass or plastic blade interior.
I did all the wiring in my car and planned it in detail. Attention to current carrying circuits and insulation is vital.Good attention to earthing is important too.

When I get an amplifier in for repair I check it's fuses looking for these signs.If the fuse tells me the amp has a short I test for short circuits with an ohmeter, because putting new fuses in and trying again can cause more damage.I find a lot of silver paper around fuses too, this is a definite no no if you care about your equipment or car fires.
A tripped circuit breaker IMHO is too easy to turn back on without the appropriate checks.

Ross

Scott Calabro · 02-25-07, 07:53 PM

Good points all !
I have to agree with Lynn though on the remote controlled relays with Aircraft spec. CB's for high load items like....
Electric fans
High powered lights
Main DC power
Alternators
High powered fuel pumps, ect.

However Ron, I'm curious as to why you would want to cut up a perfectly good RCR harness ? Why not just wire the car completely the way you want it (coundn't take more than a day or two) and put the stock harness/fuse box on the shelf for possible future use ?
Hope to see more Lola pictures soon !

Regards,
Scott