Use of relays for high current loads?

[MS19087]

Are folks using relays to switch power to high current loads like landing lights? If so, where are you obtaining them (manf & part numbers). I don't like the idea of a) using toggle breakers in this case and b) of running high current loads through small panel mounted toggle switches.

How about Avionics DC Bus - toggle breaker or relay?
Thanks for any comments!

[Jekyll]

I used a Bosch relay, PN 332-209-150 for my landing light. I bought it from Waytec.com. You can get similar relays from any auto parts store. I'm using an Infinity grip and put my L/L on the grip which can't handle 10amps. I also used one of the same for my starter button which is also on the grip.

I also used an S704-1 relay from B&C for e-bus switching because my max load can be as high as 13 amps at the worst case load.

Jekyll

[jcoloccia]

Just one man's opinion but here goes:

Why would you use a relay if a suitable switch is readily available? It's not difficult to find 10 and 15 amp switches. In fact, I would be surprised if any switch you own (other than maybe the tiny little micro switches) are rated for any less than 10 amps, and they're probably more.

If a switch is rated at 10 amps, it's not marginal at 10 amps...it's perfectly happy at 10 amps. If that weren't the case, it'd be rated at 9 amps, or 8 amps.

So for example, do you put your lights at home on an industrial relay because you don't like running 110 Volts/15 amps through a small switch? The answer is no because the switch is designed for the job.

I wouldn't use a relay anywhere except if:

a) I wanted to mount a micro switch somewhere to control something that was more than, say, 5 or 10 amps

b) it was more than, say, 10 or 15 amps and I couldn't find a reasonably priced switch, with the proper rating, that matched everything else in the panel

It's your plane and your comfort level and you should always do what you think best. I just think that with a little more information your comfort level will increase with running electrical stuff right up to it's rated limit. I wouldn't have any problem running a 10amp rated switch right up to 10 amps....maybe 9.9. .1 amps for the wife and kids....

[Rick_Luck]

I agree with the previous post. Although I didn't build my RV, I've made several electrical modifications and wouldn't consider using a relay unless the electrical load being switched was extensive or for some other reason I didn't want to extend larger wires to my panel and back, as in the starter or master electrical contactor. Personally, I think that adding a relay simply adds one more componet to fail. To my knowledge, the contact surfaces on a realy aren't any better or worse than the contact surfaces on a good switch. Depending on what you buy, either can be made in China or some third world country - or to the contrary can be high quality, long lasting alloy.


Rick Luck
RV-9A

[Kahuna]

Originally Posted by MS19087

Are folks using relays to switch power to high current loads like landing lights? If so, where are you obtaining them (manf & part numbers). I don't like the idea of a) using toggle breakers in this case and b) of running high current loads through small panel mounted toggle switches.

How about Avionics DC Bus - toggle breaker or relay?
Thanks for any comments!

I also used the bosch relay. Used in several places from the stick grip start, to the smoke pump and solenoid, main and instrument bus. These have the built in diodes. Makes wiring a bunch easier. In an all electric plane, its an effectice use of wire, weight, and routing. I cant attest to their failure rates as mine have only been running for 400 hours. So far so good.
0-332-019-155 Single pole, single throw relay. 12v, 30A inductive load w/diode, also purchased from Waytek.
Click on Molex 1 connector here


Best,

[Low Pass]

Lots of good points made above. Reliability would (generally) follow use of fewer components. I.e., use a suitable breaker/switch alone. But I can see where functionality could dictate using relays.

Also, when considering use of a relay, don't forget about solid-state. I don't have any in my plane but believe for the prices I've seen, might be a very reliable route to go.