5 pin relay wiring Question

I have a 30A 5 pin realy that I am using to wire up some lights. Should I use 1 tab to run to both lights or can I use 1 tab for each light?
This is the way to do it with one pin being used.

If you are talking about using pin 87 and 87A, DON'T. You will have one light on and the other off. They are oposite sides of the same switch.

I know this isn't really answering your question, but why don't you just get a 4-pin relay...they are only like $5.

I think if you were to wire one to 87 and one to 87A, one light will always be on when the switch is in the off position. When you flip the switch to on, that light will turn off and the other will turn on.

old_man said:

If you are talking about using pin 87 and 87A, DON'T. You will have one light on and the other off. They are oposite sides of the same switch.

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not 100% correct. they make SPST relays with dual 87 pins. and the 2nd 87 pin is labeled 87a.

those are the type i use in my hd headlight upgrade harness

FitchVA said:

not 100% correct. they make SPST relays with dual 87 pins. and the 2nd 87 pin is labeled 87a.

those are the type i use in my hd headlight upgrade harness

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That is what I thought but how can I tell if I have a SPST relay. Mine is labled 87 & 87a. I dont knw much about this but isn't a 5 pin usually used in the factory light setup to turn off the fog lamps when you hit the brights? And arn't SPST relay more $$ than the regular ones?
Edit: If I do go with using one tab for both lights I want to use pin 87 and NOT 87a Correct?

1985xjlaredo said:

That is what I thought but how can I tell if I have a SPST relay. Mine is labled 87 & 87a.

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they should have a little diagram to show you how it's wired internally. if you look at the following picture, you can see how both 87 terminals get completed when switched on. (it has the dual connection lines). if it only had one line between them, then that's the relay that will turn one on while turning the other off.

1985xjlaredo said:

And arn't SPST relay more $$ than the regular ones?

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i got mine for like $5.50/relay.

1985xjlaredo said:

Edit: If I do go with using one tab for both lights I want to use pin 87 and NOT 87a Correct?

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yeah, if it's a normally open relay

OK cool but I dont think that there is that niffty diagram on mine I guess that I will just have to do a test. Or I could quit dickin around and just wire it up using only one pin. Thanks for the replys, hope this help in someones future search!

1985xjlaredo said:

Or I could quit dickin around and just wire it up using only one pin. Thanks for the replys, hope this help in someones future search!

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yes, you can wire it up using just the 87 terminal. but be weary that the other terminal will be an exposed "hot" terminal at times (depending on the actual type of relay). me being me, i'd take the 2 seconds it would take to test it and use it accordingly

All you have do to test it is put an ohmmeter lead on 30, and successively on 87 and 87 A (with the relay disconnected, of course). If the ohmmeter indicates closed circuit on either one, it's DPDT. If both are open, it's DPST.

Ok here is a drawing of what the diagram on the package looks like
If I were to guess it is displaying that both 87 pis are hot at the same time

i kinda agree with the 4pin relay idea. it seems to work for my application...lookin for any feedback here... im goin to use this relay on a switched ground to turn on an aftermarket radio from the stock wiring in a 06 charger ive noticed that all the wires are switched ground with one power but all the wires are real tiny like 20 gauge..maybe im exaggerating but my question comes to this..if i use the switched ground as the ground for the coil on the relay..will it sustain the power draw as the wire is such a high gauge?:scared:

Small gauge should be okay for the relay coil. I assume you are switching a heavier gauge positive feed for the radio.

1985xjlaredo said:

Ok here is a drawing of what the diagram on the package looks like

If I were to guess it is displaying that both 87 pis are hot at the same time

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Correct.

If it's a 4-pin relay, it's an SPST. The fourth pin (usually pin 87 on DIN relays) is either ON or OFF. Terminals are usually numbered 30-85-86-87.

If it's a five-pin relay, it will be either SPDT or DPST - and you can tell either by the terminal numbering or the diagram that is usually either printed on or moulded into the case.

If the pins are numbered 30-85-86-87-87a, it's an SPDT relay. Pin 87 is OFF and pin 87a is ON, until the relay is tripped (then pin 87 is ON and 87a is OFF.) This type is also called a "changeover" relay, and is probably the most common DIN relay going.

If the pins are numbered 30-85-86-87-87, it's a DPST relay. Pin 87 (both of them) will behave as pin 87 in both other types of relay - you just have two of them.

Wiring conventions:
Pin 30 is the power source - this is the one that gets wired directly from the battery, the alternator, distribution, or whatever. This lead had damn well better be fused going in!
Pin 85 is the "signal" to the relay. This is the one that will come from the low-current switch you're using, be it a toggle, press button, vacuum-actuated, thermal switch, or whatever.
Pin 86 is the ground for the coil - this is the one that goes to a convenient earth terminal somewhere.
Pin 87 & 87a are for the loads. You'll usually use pin 87 for common loads - the idea behind having pin 87 and pin 87a is to provide a "logical OR" for switching back and forth between loads. Pin 87a usually goes unused.

All three relay types may be used as an SPST relay, and you can replace the four-pin relay with either of the five-pin relays, if that's all you have to hand and there are five cavities in the socket (usually the centre one isn't wired.) Check your wiring before you do the swap - and especially check if you want to switch off between the SPDT and DPST relays...

SPST - Single Pole Single Throw. Switches a single circuit either ON or OFF.
DPST - Double Pole Single Throw. Switches two circuits ON or OFF in tandem
SPDT - Single Pole Double Throw. Switches a single circuit between two possible states, as a "one or the other" option ("logical OR.")

The typical DIN relay uses about 100-150mA for the coil, so you can go down to 18AWG handily with wiring for that side. Terminal-side wiring should be sized and fused according to demand (and not necessarily to the relay capacity. You can use wiring suitable for 30A if you think you might use it for something else - then you just switch the fuse for the load you're using. However, the fuse should always be sized according to actual demand, and not circuit capacity (if you overbuild it.) If you have a power consumer rated for 10A, you can build the circuit for 30A, but the fuse had damn well better be a 10A job...

Regardless of the "true" nature of the relay, you'll need to split the downstream power feed. If you do it at the relay, you'll need to run 2 wires up to the loads. Since you never said what lights these are and where they go, the runs could be long. I would run a single wire along the shortest path to one light then split it off to the other. Make sure they are big enough to carry the load (as 5-90 said).

I'm not sure why billhrvy would need to split the power feed based on his question that related to adequate wire gauge for an aftermarket radio. I would say that 14awg that will handle 15 amps should be more than adequate for the typical aftermarket in dash headunit.

Just for clarification, I know that automotive relays with two switched
terminals out (I believe they are sometimes referred to as "dual") are often called "double pole" but they are not truly double pole in the sense of having two separate circuits in and out. True double pole relays will have a minimum of six terminals.

Pelican said:

I'm not sure why billhrvy would need to split the power feed based on his question that related to adequate wire gauge for an aftermarket radio. I would say that 14awg that will handle 15 amps should be more than adequate for the typical aftermarket in dash headunit.

Just for clarification, I know that automotive relays with two switched
terminals out (I believe they are sometimes referred to as "dual") are often called "double pole" but they are not truly double pole in the sense of having two separate circuits in and out. True double pole relays will have a minimum of six terminals.

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True, but now we're getting into industrial goodies, which can be a pain to find. And honkin' huge, sometimes.

Pelican said:

I'm not sure why billhrvy would need to split the power feed based on his question that related to adequate wire gauge for an aftermarket radio. I would say that 14awg that will handle 15 amps should be more than adequate for the typical aftermarket in dash headunit.

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If you're referring to my reply, I was replying to the OP.

I have a relay question and i figured i would post it in this thread...

I have both SPST and SPDT relays that im wiring up. Im using the SPDT Relays as SPST's (basically just not using 87a).

From what i understand, 85 and 86 on the relay can be wired anyway you want too. So the switched +12v can go to either 85 or 86 as long as the other is used for ground.

Is the same principle true for 30 and 87? When the coil is energized and the internal switch closes completing the connection between 30 and 87 i wouldnt think it would matter which way the voltage and current is flowing... Am i wrong here?

I started wiring everything up and realized i was wiring them to have 87 the fused constant +12v... so i dont want to re-wire..lol

Advice is appreciated. Thanks!

You are correct. Circuits are completely isolated and ungrounded.

Pelican said:

You are correct. Circuits are completely isolated and ungrounded.

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So you can use 87 as fused +12v input and use 30 to whatever your going to power... can anyone confirm this?