Warning - make sure your connections are properly torqued!

[sleepydoc]

I installed a 50A charging circuit a Clipper Creek charger about 3 years ago, using Polaris connectors to make the connections. I didn't have a hex socket to use when I installed them so I used an Allen wrench instead, intending to go back and check them later. Of course I forgot until spurred by a recent discussion here on TMC. When I opened the junction box this is what I found.

The connectors were properly rated, but they also needed to be torqued to 45 inch-lbs which I'm sure I wasn't able to do with just an Allen wrench. Wires for charging circuits carry a lot of current and can expand and contract with the heat generated during the charging cycles, eventually causing the connections to loosen and degrade. This increases resistance, generates heat and can lead to failures. Connectors will specify the recommended torque - even if they 'feel' tight it is wise to check.

 

[EbS-P]

I think any DIYer needs to but the bullet and get a torque screwdriver.
Wiha 28792 16 Piece Insulated Torque Control Driver and Slimline Blade Set https://a.co/d/j9R3oUG

But i haven’t…. Keep saying I need one. $300 is a lot.

 

[Electric700]

For this situation, what about just using wiring nuts and wrapping that with tape? It would still be code compliant right? If you have a slide-in wire connector, may be you can do a loop so there is no way for it to come out. This way if the screw loosens a little bit, you are still ok. But you could tape it also using electrical tape.

As another measure, I like to charge well underneath the maximum for the circuit to help reduce the heat load. So if the maximum is 32 A, I might charge at 25 A. Sure it's a little slower but overnight, I get the needed charge level and I'd rather have the reduced strain on the circuit.

 

[sleepydoc]

For this situation, what about just using wiring nuts and wrapping that with tape? It would still be code compliant right? If you have a slide-in wire connector, may be you can do a loop so there is no way for it to come out. This way if the screw loosens a little bit, you are still ok. But you could tape it also using electrical tape.

As another measure, I like to charge well underneath the maximum for the circuit to help reduce the heat load. So if the maximum is 32 A, I might charge at 25 A. Sure it's a little slower but overnight, I get the needed charge level and I'd rather have the reduced strain on the circuit.

For continuous duty the circuit should run at no more than 80% of the rated maximum or 40A for a 50A circuit.

I believe Ideal makes a wire nut that can handle 2 #6 wires. The problem is wires of that size don't necessarily twist together. They're also quite stiff and prone to coming loose as you monkey with them to get them into the box even if taped.

 

[whitex]

I think any DIYer needs to but the bullet and get a torque screwdriver.
Wiha 28792 16 Piece Insulated Torque Control Driver and Slimline Blade Set https://a.co/d/j9R3oUG

But i haven’t…. Keep saying I need one. $300 is a lot.

For DYI occasional use, you can get away with $56 (with the 30% off coupon).

https://www.amazon.com/gp/product/B09YTS1Y6C

 

[Black306]

$45 at the moment

Wheeler Engineering F.A.T Wrench With 10 Bit Set

Wheeler Engineering F.A.T Wrench® With 10 Bit Set -Wheeler’s F.A.T Wrench® brings perfect consistency to every screw on your rifle!The F.A.T Wrench® is a perfect compliment to the Deluxe Gunsmithing Screwdriver Sets. Together, they can ensure accurate tightening of most every screw on any gun in...

www.sportsmans.com

 

[EbS-P]

For DYI occasional use, you can get away with $56 (with the 30% off coupon).

https://www.amazon.com/gp/product/B09YTS1Y6C

Purchased!!!! Thanks.

 

[Jerryr]

I've seen much worse burring with Polaris connectors.

With the stranded wire, not just polaris connections but all connections like at receptacles, breakers etc should be tightened then wires wiggled then loosen -tightened then wiggled tightened etc repeatedly until no more tightening is felt. Then torque to spec.

If not done then temp cycling will tend to loosen the connection causing high resistance, heating and eventually burning.

EDIT:

Check out this video at 40:00 describing wiggling

 

[whitex]

I've seen much worse burring with Polaris connectors.

With the stranded wire, not just polaris connections but all connections like at receptacles, breakers etc should be tightened then wires wiggled then loosen -tightened then wiggled tightened etc repeatedly until no more tightening is felt. Then torque to spec.

If not done then temp cycling will tend to loosen the connection causing high resistance, heating and eventually burning.

EDIT:

Check out this video at 40:00 describing wiggling

Couldn't help but notice in that video that the guy never grounded the receptacle box, relying on the bare ground wire hopefully making sufficient contact by itself. Growing up in a family of electricians and electrical engineers - "always connect your grounds solid - it's your safety".

 

[sleepydoc]

Couldn't help but notice in that video that the guy never grounded the receptacle box, relying on the bare ground wire hopefully making sufficient contact by itself. Growing up in a family of electricians and electrical engineers - "always connect your grounds solid - it's your safety".

Nominally the connection with the outlet frame *should* ground the box but that’s not code and there’s a reason it’s not code.

 

[whitex]

Nominally the connection with the outlet frame *should* ground the box but that’s not code and there’s a reason it’s not code.

And that is why I prefer to do my own wiring installations at home - I sleep better knowing it's done right.

 

[Jeff-4]

$45 at the moment

Wheeler Engineering F.A.T Wrench With 10 Bit Set

Wheeler Engineering F.A.T Wrench® With 10 Bit Set -Wheeler’s F.A.T Wrench® brings perfect consistency to every screw on your rifle!The F.A.T Wrench® is a perfect compliment to the Deluxe Gunsmithing Screwdriver Sets. Together, they can ensure accurate tightening of most every screw on any gun in...

www.sportsmans.com

I also purchased this to get a firmer fit into the hex nuts of the Polaris connector: https://www.amazon.com/gp/product/B07CTB1JC9/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

 

[Jerryr]

Couldn't help but notice in that video that the guy never grounded the receptacle box, relying on the bare ground wire hopefully making sufficient contact by itself. Growing up in a family of electricians and electrical engineers - "always connect your grounds solid - it's your safety".

If conduit was continuous run from the freakier box to the outlet box the the conduit would be the grounding path.

Couldn't help but notice in that video that the guy never grounded the receptacle box, relying on the bare ground wire hopefully making sufficient contact by itself. Growing up in a family of electricians and electrical engineers - "always connect your grounds solid - it's your safety".

Good catch.

 

[SunnylandY]

For this situation, what about just using wiring nuts and wrapping that with tape? It would still be code compliant right? If you have a slide-in wire connector, may be you can do a loop so there is no way for it to come out. This way if the screw loosens a little bit, you are still ok. But you could tape it also using electrical tape.

As another measure, I like to charge well underneath the maximum for the circuit to help reduce the heat load. So if the maximum is 32 A, I might charge at 25 A. Sure it's a little slower but overnight, I get the needed charge level and I'd rather have the reduced strain on the circuit.

I do the same thing even though some have told me I'm silly. When I was using the mobile connector (on a cheap Leviton 14-50) at 30A I noticed both the cord and the plug were getting warm... not alarmingly hot, but clearly well above ambient temperature. I had to dial it all the way down to 16A before it stayed cool. Doing so didn't affect my lifestyle a bit. When I upgraded to the wall connector I figured it was heavier duty and would stay cool no matter what, but found that running it above 24A also resulted in the cord getting warm. As a result the only time I go above 24A is on very rare occasions I'm in a hurry.
Sure I get it, it's rated to handle getting warm but there's a lingering question whether that is shortening its life or inviting problems at these connections. There's also gotta be some wasted energy being dissipated as heat. Whether that's more or less than any additional overhead of longer charging time I can't say.
There's also another connection people don't think of, the breaker contacts at the bus bar. I have seen these arc and require panel change outs on air conditioner breakers.
Bottom line why invite trouble if you don't have to.

 

[EbS-P]

I do the same thing even though some have told me I'm silly. When I was using the mobile connector (on a cheap Leviton 14-50) at 30A I noticed both the cord and the plug were getting warm... not alarmingly hot, but clearly well above ambient temperature. I had to dial it all the way down to 16A before it stayed cool. Doing so didn't affect my lifestyle a bit. When I upgraded to the wall connector I figured it was heavier duty and would stay cool no matter what, but found that running it above 24A also resulted in the cord getting warm. As a result the only time I go above 24A is on very rare occasions I'm in a hurry.
Sure I get it, it's rated to handle getting warm but there's a lingering question whether that is shortening its life or inviting problems at these connections. There's also gotta be some wasted energy being dissipated as heat. Whether that's more or less than any additional overhead of longer charging time I can't say.
There's also another connection people don't think of, the breaker contacts at the bus bar. I have seen these arc and require panel change outs on air conditioner breakers.
Bottom line why invite trouble if you don't have to.

Warm is ok. Ever felt the plugs on a waffle iron after running it. Wire is not zero resistance so any amount of current generates heat. Bad connections reduce surface area in contact creating regions of higher current and or arcing.

Normal operations it will be warm. How warm needs to be quantified or all the connections check for proper install and functionality.

 

[SunnylandY]

Warm is ok. Ever felt the plugs on a waffle iron after running it. Wire is not zero resistance so any amount of current generates heat. Bad connections reduce surface area in contact creating regions of higher current and or arcing.

Normal operations it will be warm. How warm needs to be quantified or all the connections check for proper install and functionality.

I don't doubt that warm is "ok" but will it be ok forever? Or will expansion and contraction cause issues over time? Cool seems better than warm.
As for the waffle iron I might use that for half an hour once a year. The evse is used every day for hours on end.
Maybe I'm wrong and there is no benefit to what I'm doing but it seems to be working fine. I know people who have melted 14-50 outlets and suspect that never would have happened had they run at 16amps.

 

[whitex]

I don't doubt that warm is "ok" but will it be ok forever? Or will expansion and contraction cause issues over time? Cool seems better than warm.
As for the waffle iron I might use that for half an hour once a year. The evse is used every day for hours on end.
Maybe I'm wrong and there is no benefit to what I'm doing but it seems to be working fine. I know people who have melted 14-50 outlets and suspect that never would have happened had they run at 16amps.

You are right that de-rated usage is less stress, less expansion contraction - definitely better for cabling, breakers. However, on the flip side of the coin however, you are running the AC charger, DC-2-DC converter, and other car electronics for a longer time, so reaching MTBF of the electronics quicker. Same for battery cooling/heating pumps, radiator fans, etc - they all are running longer. Those components also use energy for longer. I cannot tell you where the perfect balance is, not even sure anyone at Tesla knows. They designed it to charge at specific levels, make sure it lasts the designated lifespan, so I don't worry about it.

Side note, Porsche issued an advisory for their EV customers to not regularly use L1 charging - besides being slow, evidently it does significantly affect the runtime of various components, enough for Porsche to notice on the warranty side I guess. L1 is way slower than what you use, just mentioning the fact that too slow may actually be bad for the car overall.

 

[EdJack]

I see lots of issues with your setup:

(1) Wire Nut connectors should be used.
(2) Box should be a Steel Box, not plastic.
(3) Conduit should be 1/2" EMT Pipe, not PVC.
(4) Entire length of run, from Breaker Box, EMT Pipe, Steel Box, all Conduit Connectors, to Clipper Creek Charger should have an end-to-end ground throughout all the metal parts.
(5) Optionally, you could run a green ground wire through the conduit for additional protection in case conduit sections detach or pull apart.
(6) Optionally, use a deeper Steel Box and 3/4" EMT Pipe, because your wires look really crammed up in there. Overstuffed boxes and conduit will overheat the wires.

 

[pontelaspilas]

are you able to tell what got hot and melted? the polaris connectors? i wonder if split bolts would have had the same heat issue. couldn't direct wire?

 

[EdJack]

couldn't direct wire?

I believe the Clipper Creek charger has a built in short pigtail, about 12 inches. And you have to wire it up to that pigtail. I don't believe you can direct wire a Clipper Creek. I also don't think you can open it up and get rid of the pigtail, it's factory built into the unit.

Which is one more reason to go with a Tesla Wall Connector, or even Juicebox or something, that allows you to direct wire.

Yes, if the box could be direct wired, then this problem with the burnt up and melted box goes away.