Which contactor/relay for 60a panel build?

[SenorWanderer]

Hi all,

I've been piecing together the parts for a mostly kal style control panel for what seems like years now. It's finally time to finish this project and I've run into a snag. The last components I purchased were a 60a spa panel and the plugs required to supply that power to the panel. I chose 60a because at the time, my house was receiving only ~218V-220V, and I was worried I'd continually blow the GFCI of a 50a panel. A few months later the transformer out on the pole blew, they replaced it, and guess what: I'm getting 248V measured on my main panel. The problem is that I also bought what I thought was an 80a relay with a 240v coil. the coil is actually 24v. here's a link for the exact model from amazon: 24V Coil DPDT High Power Relay, 80A/240VAC.

So obviously I can't use this (or can I!? I'm so confused!), but I'm having trouble finding something I can use. I don't know enough to know what other part would be suitable. I read another, very old post recently that mentioned using something like this. Would that work? I wouldn't have a clue how to wire that, but thankfully my buddy that's going to help me with the build is an electrical engineer. The caveat is that I need to show up with all the correct parts ready to go!

Any suggestions? I see lots of threads about 60a panels, but none that are calling out parts.

Thanks again for the help!

 

[processhead]

Just based on the specs alone, either one would work.

When building a panel, it helps to have some consistency in what control voltage you want to use for things like contactor coils and the like.

For control voltage, 24 volts DC or 240 volts AC will work, you just need to be consistent throughout the panel. Personally, I prefer using a lower control voltage since it often is wired to low voltage devices, and I just think it is safer.

I looked at both of the relays you included links to. To be honest, I would not use the first relay. There is no agency certification like UL or CE, and it just looks... cheesey. The second one looks much better, IMO.

Again, the specs for both are workable, but you do need to make a decision on control voltage. Staying consistent helps make a cleaner panel design and build.

 

[SenorWanderer]

Thanks for the reply, processhead.

so my goal for the panel is to combine the instructions for 220/240v countries and back to back panels. so i want to run everything on 240v with enough amps to have both elements running. combining the requirements for the power in relay leaves me with needing a 50a/240v relay with a 240v coil, according to the instructions. so does that mean that the kal instructions control everything on 240v? and if use my 24v DC relay i'll simply be controlling everything on that 24v DC? if so then what would that mean for the components i'll need?

thanks as always!

 

[processhead]

Thanks for the reply, processhead.

so my goal for the panel is to combine the instructions for 220/240v countries and back to back panels. so i want to run everything on 240v with enough amps to have both elements running. combining the requirements for the power in relay leaves me with needing a 50a/240v relay with a 240v coil, according to the instructions. so does that mean that the kal instructions control everything on 240v? and if use my 24v DC relay i'll simply be controlling everything on that 24v DC? if so then what would that mean for the components i'll need?

thanks as always!

I'm not sure I can speak to your specific application without learning more about it.

Generally speaking, if you are running power relays with a lower coil voltage than the incoming line voltage, a step-down control transformer or DC low voltage power supply has to be included in the panel.

A simple control transformer can provide a low voltage AC power source for control power.
A DC power supply can provide a low voltage DC power source for control power.

Which one you use or whether you use one at all is dictated by your panel design, or the plans somebody else designed.

 

[augiedoggy]

Just based on the specs alone, either one would work.

When building a panel, it helps to have some consistency in what control voltage you want to use for things like contactor coils and the like.

For control voltage, 24 volts DC or 240 volts AC will work, you just need to be consistent throughout the panel. Personally, I prefer using a lower control voltage since it often is wired to low voltage devices, and I just think it is safer.

I looked at both of the relays you included links to. To be honest, I would not use the first relay. There is no agency certification like UL or CE, and it just looks... cheesey. The second one looks much better, IMO.

Again, the specs for both are workable, but you do need to make a decision on control voltage. Staying consistent helps make a cleaner panel design and build.

I used all 24v coil and control devices myself in my panel... My solenoid valves for my glycol, pumps and even my conical heating strips all run off 24v... my estop cuts this voltage from the panel and coils.

 

[processhead]

I used all 24v coil and control devices myself in my panel... My solenoid valves for my glycol, pumps and even my conical heating strips all run off 24v... my estop cuts this voltage from the panel and coils.

Using 24 volts to power field devices makes a lot of sense from a safety standpoint. When you are controlling field devices in your system that are close to wet processes, or in areas where they might be physically damaged, then its less hazardous to the user to use a low voltage power source.
Add to that the wide array of devices that are out there that can be powered by 24 volts, and it makes the choice even easier.

 

[doug293cz]

Using 24 volts to power field devices makes a lot of sense from a safety standpoint. When you are controlling field devices in your system that are close to wet processes, or in areas where they might be physically damaged, then its less hazardous to the user to use a low voltage power source.
Add to that the wide array of devices that are out there that can be powered by 24 volts, and it makes the choice even easier.

Agreed that for sensors and actuators outside the control panel, low voltage is the safest choice. However, I don't think there is a safety advantage to low voltage vs. line voltage for things contained within the control panel enclosure. For inside the panel I think it's safe to make voltage choices based on cost and simplicity.

Brew on

 

[augiedoggy]

Agreed that for sensors and actuators outside the control panel, low voltage is the safest choice. However, I don't think there is a safety advantage to low voltage vs. line voltage for things contained within the control panel enclosure. For inside the panel I think it's safe to make voltage choices based on cost and simplicity.

Brew on

arent there cost measures to think about to? for example the wire gauge for 24v is smaller than whats allowed for 240V. my other though process is since im trying to build something now for a 3 bbl micro , I think the inspector may not be as critical if all the control devices and dc wiring are in one panel and all the ac components are in two others. with multipin aviation connectors to send control signals

 

[processhead]

arent there cost measures to think about to? for example the wire gauge for 24v is smaller than whats allowed for 240V. my other though process is since im trying to build something now for a 3 bbl micro , I think the inspector may not be as critical if all the control devices and dc wiring are in one panel and all the ac components are in two others. with multipin aviation connectors to send coontrol signals

Choice of wire size is dictated by the current (amperage) requirements of the device being powered, not the voltage. For control power in a panel, wire size may not be significantly different between 24 volt and 240 volts systems because in either case, control power is typically used to drive low power devices like relay coils, solenoids, indicating lamps and instrumentation. All of which are fairly low current consumption devices.
Often control wire size will be larger than actual power requirements, and will be chosen more for physical durability or compatibility with terminal blocks and terminal connections on devices. Its also easier to make a good crimp connections on a AWG 14 or 16 wire than it is on a AWG 20 or 22.

Its is very common to have low voltage control power devices and line voltage devices all located in one panel. You can separate them if you wanted to but it just adds to the cost and complexity of the project.

 

[doug293cz]

Choice of wire size is dictated by the current (amperage) requirements of the device being powered, not the voltage. For control power in a panel, wire size may not be significantly different between 24 volt and 240 volts systems because in either case, control power is typically used to drive low power devices like relay coils, solenoids, indicating lamps and instrumentation. All of which are fairly low current consumption devices.
Often control wire size will be larger than actual power requirements, and will be chosen more for physical durability or compatibility with terminal blocks and terminal connections on devices. Its also easier to make a good crimp connections on a AWG 14 or 16 wire than it is on a AWG 20 or 22.

Its is very common to have low voltage control power devices and line voltage devices all located in one panel. You can separate them if you wanted to but it just adds to the cost and complexity of the project.

Excellent post! Saved me some typing! Only thing I would add is that voltage rating is determined by insulation type and thickness, so even if the AWG is the same, for 240V you need wire rated higher than 240V. I doubt that there is a significant cost impact for the higher voltage rated wire on small projects, since most of the cost is in the copper.

Brew on

 

[processhead]

Doug293CZ is correct on the insulation rating for various voltages.

In my last post I had typed half a paragraph on wire insulation and then deleted it since it technically was't part of the auggydoggie's question on wire size.

But it is certainly relevant to the discussion when planning to build a panel and getting the appropriate material for the voltages being used.

If you need wire for line voltage service, don't buy a roll of primary wire at the auto parts store thinking you are getting the right material, even if the gauge is correct.

 

[augiedoggy]

Choice of wire size is dictated by the current (amperage) requirements of the device being powered, not the voltage.

Good to know. I read here a few times that wire size under 16 was not allowed by nec for any 240v applications... I currently have 22 awg wire for various dc voltages along with some heavier wire depending on amperage as im aware of the wire size needing to be adequate for the load but I also realize this logic doesnt necessarily mean things are going to pass nec code since there are a lot of "one size fits all" application rules to simplify things making something not allowed even though in reality it would be completely safe when looking at it logically for one application because it might not be in a similiar setup which is why Im asking here.

 

[augiedoggy]

Doug293CZ is correct on the insulation rating for various voltages.

In my last post I had typed half a paragraph on wire insulation and then deleted it since it technically was't part of the auggydoggie's question on wire size.

But it is certainly relevant to the discussion when planning to build a panel and getting the appropriate material for the voltages being used.

If you need wire for line voltage service, don't buy a roll of primary wire at the auto parts store thinking you are getting the right material, even if the gauge is correct.

yes I learned about the auto wire not being "tested" for the ac application and the insulation being made for oil resistance and not always able to hold up in ac applications.... I also learned that many places like harbor frieght sell wire thats not specified for particular use... My original panel used this wire and although I have had zero issues with it years later I realize now it likely wouldnt pass code since if it was ul listed and certified for the application the cost would likely be inflated .

Anyway sorry to derail the thread...

 

[processhead]

Agree.
When you examine NEC rules on a case by case basis, they often seem arbitrary and illogical.

You could debate some of this stuff forever. It makes it more difficult to discuss how to build our electrical brewing equipment in a cost effective way.