Help me understand a terminal strip/block

[Cioffi]

So after searching for info on terminal strips/blocks, I still have some questions. I'll be using one of P-J's wiring diagrams and as far as I can tell, the power source in wires go to terminal blocks and then from there are wired to plugs, pumps, etc. So, for example, if one of the hot wires is wired to the block, then do all the "outgoing" terminals get energized? From what I gather this is not necessarily the case, which is why folks talk about jumper strips, etc. Is there a block I can get for, say, 4 to 8 terminals that has one incoming wire and then energizes all the outgoing terminals without having to use a bunch of jumper strips? Or, am I just completely misunderstanding how a terminal block works?

Thanks
Todd

 

[MrNatural]

pick your flavor, here:
http://www.elecdirect.com/catalog/8063c3d2-b684-4c58-b7f1-c885828651cc.aspx

 

[P-J]

So after searching for info on terminal strips/blocks, I still have some questions. I'll be using one of P-J's wiring diagrams and as far as I can tell, the power source in wires go to terminal blocks and then from there are wired to plugs, pumps, etc. So, for example, if one of the hot wires is wired to the block, then do all the "outgoing" terminals get energized? From what I gather this is not necessarily the case, which is why folks talk about jumper strips, etc. Is there a block I can get for, say, 4 to 8 terminals that has one incoming wire and then energizes all the outgoing terminals without having to use a bunch of jumper strips? Or, am I just completely misunderstanding how a terminal block works?

Thanks
Todd

When you mount the terminal blocks, the vendor generally offers terminal strips that can be cut to redistribute the electrical connections to the assigned & intended output.

Do some search & if you need some more info & ideas just let me know.

Here is an example of a jumper strip:

That can be cut to size to make the terminal strip a multi connection.

P-J

 

[Cioffi]

I think I'm understanding a bit better. So, it seems like it may make sense to buy something that has one input with, say, four outputs. Is there a good reason not to do that?

As for your diagrams, P-J, which terminal blocks and the like do you recommend, as I'll be following one of your diagrams?

Thanks,
Todd

 

[Walker]

I think I'm understanding a bit better. So, it seems like it may make sense to buy something that has one input with, say, four outputs. Is there a good reason not to do that?

Normally, just cost. There are little bricks called something like "power distribution blocks" or something that are exactly what you describe. They are a block of (aluminum?) with several screw-down terminals on them. They typically cost a lot more than the terminal strips, and can only be used for a single pole, so you have to buy one for hot, one for neutral, one for the other hot (if using 240v).

The terminal strips are cheaper. Asa bonus, they are more flexible since you can jumper as many pairs together as you want.

 

[theknub]

so this is what i used http://www.amazon.com/gp/product/B000OTJ89Q/?tag=skimlinks_replacement-20

i am happy with them so far.

 

[smittygouv30]

I picked up my distribution blocks from mouser. No jumpers required. I can get you the part number if you are interested. I want to say they were 7 or 8 bucks and are DIN mountable. I have 2 in my control panel that you can see down at the bottom.

 

[Walker]

I picked up my distribution blocks from mouser. No jumpers required. I can get you the part number if you are interested. I want to say they were 7 or 8 bucks and are DIN mountable. I have 2 in my control panel that you can see down at the bottom.

I think you might be running a risk here. I use those same modular din rail distribution modules in my system, but you are absolutely supposed to use a jumper to bridge adacent modules on the rail.

Adjacent ones do make a little bit of contact, but that is incidental and not indended to be the main way that they connect. You are supposed to get one of these things:
http://www.mouser.com/Search/ProductDetail.aspx?R=CA723/10virtualkey56110000virtualkey845-CA723/10
cut it into pieces, drop the finders down into the holes on the top-sides of those modules. and screw them down tight to bridge them.



edit: I take that back. Maybe the things you are using are slightly different. Are yours made of a large center lug with 2 smaller modules on each side of it?

I'd be interested in that part number for sure!!! Those look jazzy.

 

[Cioffi]

I picked up my distribution blocks from mouser. No jumpers required. I can get you the part number if you are interested. I want to say they were 7 or 8 bucks and are DIN mountable. I have 2 in my control panel that you can see down at the bottom.

I would be interested in the part numbers. Thanks for the pic, too!

 

[BadNewsBrewery]

To the rescue!

These things are great. This is the 6/2 - 1 input, 12 total outputs (6 on each side). You can also search for CDB 4/2 on Mouser and find one with 8 outputs. I uses these for each leg of the 240 supply - neutral, ground, and both hots. They're great, you don't have to worry about jumpers, and you can color code them or label them to be clearly definable. Plus it keeps all your connections in one place and nice and clean.

 

[MrNatural]

Those look sweet! But max wire size is 8AWG, and won't work for my 50A build
Gotta get my search mojo going............

 

[BadNewsBrewery]

Well, hold on a second... I think the max wire size is for the individual screw terminal holes. The main line in is a post. I am running a 6 gauge wire to each post no problem. I then break out with 10awg to the 3 breakers I have, and then all the smaller things downstream of the 15amp breaker are actually on their own terminal block as well, though I used a different version for that - I used the eBrewSupply.com DIN Rain Terminal Blocks with DIN rain connecting bridges.

So it should still work fine. Just keep in mind that if you run your lines straight from the main power contactor (assuming you use one) to the terminal block, anything you tap off that terminal block will NOT be fused. I'm willing to accept the risk on the short run between the terminal block and the breaker.

 

[Walker]

I'm willing to accept the risk on the short run between the terminal block and the breaker.

Yup. No problem there. This is even considered kosher under the NEC "feeder tap" rule.

It's ok to have an undersized wire as long as that wire is short enough, doesn't leave the enclosure, and connects to an appropriately sized over current device.

 

[MrNatural]

Well, hold on a second... I think the max wire size is for the individual screw terminal holes. The main line in is a post. I am running a 6 gauge wire to each post no problem. I then break out with 10awg to the 3 breakers I have, and then all the smaller things downstream of the 15amp breaker are actually on their own terminal block as well, though I used a different version for that - I used the eBrewSupply.com DIN Rain Terminal Blocks with DIN rain connecting bridges.

Awesome. Do you recall what diameter the main line in post is? I have some copper ring lugs left over from solar battery bank build that might work perfectly.

 

[Cioffi]

Okay, all this is helpful. So now my next question: I have one of those Xerox cords with GFI attached on the cord. I'll be running this from my dryer outlet to my control panel. I don't need to hook up to the control panel by way of a plug (so female receptacle on the end of the cord to male plug attached to the control panel). Instead, I want to hard wire the cord to the control panel. Given this, four wires will be sticking out inside the control panel. Do I run each wire to a terminal block and then wire from the blocks to the on/off contactor, etc.?

 

[BadNewsBrewery]

Contactor before anything. Then from contactor to terminal strip and on from there.

No idea on the post diameter but it should fit standard rings.

 

[summerofgeorge]

Those look sweet! But max wire size is 8AWG, and won't work for my 50A build
Gotta get my search mojo going............

I know BadNewsBrewery and Walker ok'd using an undersized wire but if you're concerned you can go with the CDB10/x version. This takes up to 6 AWG wire.

 

[summerofgeorge]

awesome. Do you recall what diameter the main line in post is? I have some copper ring lugs left over from solar battery bank build that might work perfectly.

cdb6 - m6
cdb10 - m8

 

[Cioffi]

Contactor before anything. Then from contactor to terminal strip and on from there.

No idea on the post diameter but it should fit standard rings.

Okay, but why in P-J's diagrams does it look like the incoming wires, from the power source, are attached to terminal blocks and then on to various components? If to a contactor first, how do all four wires hook up to the contactor?

 

[MrNatural]

cdb6 - m6
cdb10 - m8

Thanks, guess I could have looked it up myself...
M8 should work, thinking the ring lugs are 5/16 or 3/8. Will be running 10awg and 14awg downstream.

Okay, but why in P-J's diagrams does it look like the incoming wires, from the power source, are attached to terminal blocks and then on to various components? If to a contactor first, how do all four wires hook up to the contactor?

Only need to run the two hot legs through contactor. Neutral and ground run directly to terminal blocks.

 

[jeffmeh]

Okay, but why in P-J's diagrams does it look like the incoming wires, from the power source, are attached to terminal blocks and then on to various components? If to a contactor first, how do all four wires hook up to the contactor?

Just the two hot wires go through the contactor. Some of P-J's diagrams do not use a switch and contactor as a "main power on/off," but use an EPO switch to shunt a small amount current to ground and trip the GFCI.

 

[Cioffi]

Just the two hot wires go through the contactor. Some of P-J's diagrams do not use a switch and contactor as a "main power on/off," but use an EPO switch to shunt a small amount current to ground and trip the GFCI.

Okay, things are making sense to me now. However, this last comment about using an "EPO switch to shunt a small amount of current to ground the and trip the GFCI" is not making sense. What is that?

 

[P-J]

Okay, things are making sense to me now. However, this last comment about using an "EPO switch to shunt a small amount of current to ground the and trip the GFCI" is not making sense. What is that?

If you do not understand it or the concept, PLEASE do not incorporate even a remote idea of it in your wiring plan.

 

[Psych]

Just use marrettes, you can easily have four wires securely combined in there. If it's good enough for use inside my walls at every wire junction in the house, it's good enough in my control box.

And they're cheaper and easier use. Maybe don't look as nice, but meh...how often will you ever look in there once built?

 

[Cioffi]

If you do not understand it or the concept, PLEASE do not incorporate even a remote idea of it in your wiring plan.

Okay. So is the best way to run the four wires into the panel to use a contactor as stated above and use an on/off switch?

 

[jeffmeh]

Okay. So is the best way to run the four wires into the panel to use a contactor as stated above and use an on/off switch?

The "best" way is debatable, but the method I favor is to run both hots through a DPST mechanical contactor with a 120v coil, with a "main power" switch. When that switch is off, the panel is off, with hot wires only at the switch and both line terminals of the contactor.

If you really want to understand this stuff http://www.theelectricbrewery.com is a great reference. Understand that and you are likely competent to build your own, although asking questions is always encouraged.

 

[jeffmeh]

I have a couple of questions regarding using the basic terminal strips.

1) Is it acceptable to use the same terminal strip for both hot and neutral lines, assuming of course that you do not use a jumper that would connect hot and neutral?

2) Is it acceptable to use a terminal strip as a ground bus, and if so, can it share the same terminal strip as described above, as long as hot, neutral, and ground are isolated from one another?

If each contact pair is really isolated from the adjacent ones on a terminal strip, I don't see why this would be a problem, but if this is bad practice I could certainly obtain separate terminal strips.

 

[P-J]

I have a couple of questions regarding using the basic terminal strips.

1) Is it acceptable to use the same terminal strip for both hot and neutral lines, assuming of course that you do not use a jumper that would connect hot and neutral?

2) Is it acceptable to use a terminal strip as a ground bus, and if so, can it share the same terminal strip as described above, as long as hot, neutral, and ground are isolated from one another?

If each contact pair is really isolated from the adjacent ones on a terminal strip, I don't see why this would be a problem, but if this is bad practice I could certainly obtain separate terminal strips.

There is no problem at all in doing it the way you describe. The terminal strips should have an insulated barrier strip between each connection. Jumpering adjecent terminals together requires a special jumper strip.

P-J

 

[The10mmKid]

I have a couple of questions regarding using the basic terminal strips.

1) Is it acceptable to use the same terminal strip for both hot and neutral lines, assuming of course that you do not use a jumper that would connect hot and neutral?

2) Is it acceptable to use a terminal strip as a ground bus, and if so, can it share the same terminal strip as described above, as long as hot, neutral, and ground are isolated from one another?

If each contact pair is really isolated from the adjacent ones on a terminal strip, I don't see why this would be a problem, but if this is bad practice I could certainly obtain separate terminal strips.

We will use the terminal strip for ALL lines. We usually size it large enough to have some spare spaces between 'phases'.
For old school strips we use these jumpers to tie 3-4 or more together.

The grounds we try to terminate all of them under a single screw/bolt. Usually with ring terminals and in the corner where the feeds come in.

'da Kid