Double ended male plug without shocking risk?

[Strouty]

OK, so I am not trying to make an extension cord, I am trying to wire up my truck block heater so I can plug it in from the front or rear depending on where I am without making both ends hot. Think junction box to input cords and the block heater. Is there a way to do this? I know generator transfer switches can keep the line workers safe, is there a simple way for this or am I dreaming? I figured I could use enclosed plugs, so you would have to lift a flap up to get to the juice.

 

[850xpeps]

Had this on my last truck. Ends would still be live but at least hidden. Why not run cord up to front and just plug/unplug there as needed

 

[Strouty]

At my house my outdoor outlet forces me to be really close to the house, I take my GF's usual parking space and I have to pull nose in. I prefer backing in as it is hard to see backing out and there are idiots everywhere. If I back in on the far side the cord reaches the rear, but I have to use a second extension cord to get to the front, plus the plug is literally 12" from the road.

I have found this, not sure if it is what I need, but looks like it.


https://www.boatandrvaccessories.com/products/xantrex-808-0915-15-amp-transfer-switch

 

[SGKent]

just use one of these or something like it on the truck. https://www.amazon.com/dp/B003ATXIBG/?tag=atomicindus08-20

or maybe one of these https://www.amazon.com/dp/B01E6N0XFI/?tag=atomicindus08-20

you could add a switch at each one to turn it off when not using.

 

[The Cobbler]

......s, not sure if it is what I need, but looks like it.


https://www.boatandrvaccessories.com/products/xantrex-808-0915-15-amp-transfer-switch

looks like it would work

just use one of these or something like it on the truck. https://www.amazon.com/dp/B003ATXIBG/?tag=atomicindus08-20

doesn't relieve the fact that one end will be hot when the other end is plugged in

 

[Strouty]

I feel like for $50 it isn't too steep a price to have only one end be live. Shocking myself, someone else, or shorting out for some reason would be dumb if this will solve the issue.

 

[SGKent]

since someone has to get out of the truck regardless where they park, why not just put it on a bracket near the driver's door or whatever door one will use to get in and out?

I had added put a switch in at each location but it makes more sense to put the plug in near where one gets in and out of the truck instead of one at each end of the truck.

 

[Strouty]

Front or rear of the truck is better in all my parking situations. I think I am going to try this and see what happens. Seems like it should work for what I need, just have to figure out placement of everything.

 

[mike93lx]

How about a blank plug to cover the ends when not in use? Put one on each side, tethered some how.

 

[Strouty]

Drawing things up, I think if I use the transfer switch, I don't need a junction box, so it makes it less expensive. I am going to try one and see if it works like I want, then I can wire other trucks the same way.

 

[oldtimer]

I would use a DPDT switch with block heater connected to center contacts.
Somthing like this: Leviton 1286-W 20-Amp 120/277-Volt Toggle Double-Pole AC Quiet Switch

 

[harley jim]

Put female ends on both ends of the truck and make a double redundant to put in which ever end you want to use

Sent from my SM-A102U using Tapatalk

 

[95vette]

Hello, Why not just ty wrap a drop cord under the truck to the rear, and use which ever end you need when you park??

 

[Kevin Essiambre]

I would install a 3 way switch in the cab, with the block heater wired to the common on the switch. The other 2 screws would be for the different plugs. Label one front and one rear, and just flick the switch when you park to select the one you need.

Sent from my new phone. Autocorrect may have changed stuff.

 

[JRC3]

How about a second block heater? Is that even possible? IDK.

 

[Kevin Essiambre]

How about a second block heater? Is that even possible? IDK.

On some vehicles I believe it's possible. Never done it myself.

Sent from my new phone. Autocorrect may have changed stuff.

 

[mm08822]

Two 4 pole double throw relays could be used. The first relay energized locks out the other. This prevents backfeeding unused plug.

What is the block heater voltage and wattage?

 

[u3b3rg33k]

How about a second block heater? Is that even possible? IDK.

they're often freeze plug replacements, so yes, it's possible. probably depends on the engine.

 

[alfredeneuman]

Why don't you just use an extension cord?
If you're worried about where to store it when not in use you could mount a retractable cord reel.

 

[welder4956]

Why not put one of these on each plug?

https://www.amazon.com/Protector-Engine-Block-Heater-Cords/dp/B075324GBZ/ref=pd_cp_263_2/130-2685052-9343169?_encoding=UTF8&pd_rd_i=B075324GBZ&pd_rd_r=901228c1-411c-4c00-997f-c80bb1cabc26&pd_rd_w=QYPLu&pd_rd_wg=3mYov&pf_rd_p=0e5324e1-c848-4872-bbd5-5be6baedf80e&pf_rd_r=1MBB06QZJG1YMV7FSCRQ&psc=1&refRID=1MBB06QZJG1YMV7FSCRQ

 

[Kevin Essiambre]

You could go all out with an arduino and some relays and something to sense the power. When the arduino senses power from one plug it selects that one and locks out the other so that you can't double feed it or backfeed it.

Sent from my new phone. Autocorrect may have changed stuff.

 

[slow]

That's basically what the $50 switch does, but it is made for that purpose.

2 contactors could work as well, where the coil and line are connected to the plug and both load sides are connected to the block heater. Even better would be have them isolated so if either contactor is on, the other one cannot be turned on.

I like the 2 block heater idea the best, clean, safe and if you really need to you can power both at the same time.

 

[Brandon_oma#692]

From what you are saying I am assuming that you pull in and plug the truck cord directly into an outlet?

I have never parked anywhere where I can plug my truck in without an extension cord so I just use a short one that is long enough to plug in at the front bumper if I pull in or back in. I really don't see any problem with this. I also loop it over the drivers door mirror so I can't forget to unplug it.

Do you leave it plugged in all night? I usually keep mine on a timer to turn for a few hours in the morning. I actually need to replace the cord on mine. It is currently laying on the passengers floor as a reminder to order a replacement.

 

[Strouty]

I like to back in, I have to run a cord to the front, it is basically in the street and I don’t like it. I want to have it in the back of the truck at my house, but at my shop it is opposite, there is always an extension cord involved, I like the options of front or rear outlets.

 

[pancho400cid]

As you know, the heater is "dumb" and doesn't care where the power is coming from so two source wires connected in parallel with the heater leads is the basic idea. You would end up with one hot male plug exposed, when the other plug is plugged into an extension cord as you already said. That is super-dangerous - all of which you already know.

If it was me, I would look at the device in the earlier link above, or I would use two recessed male plugs with spring loaded covers. I personally would not rely on anything that did not have spring-loaded covers. Even at that, it's a sketchy set-up for "informed adults" and not for use in areas where a kid could poke his fingers etc.

Something like this (I "think" the cover is spring-loaded):

https://www.homedepot.com/p/Leviton-15-Amp-125-Volt-Straight-Blade-Grounding-Power-Inlet-Outlet-Gray-001-05278-CWP/301304898

Cost-wise it would be as much or more than the device in the earlier link... so there's that...

 

[LS6 Tommy]

I realize that NEC might not necessarily apply to a vehicle, but by code, inlet connectors like the ones linked to are required to be de-energized when not in use for a reason. I don't think that transfer switch will do what the OP wants to do. All he needs is an "A/B switch" between the two inlet cords and the block heater, which could be accomplished with a standard SPDT toggle switch to select one input "hot" or the other. If the OP really wants to go nuts and isolate the neutrals, he can use a DPDT switch like oldtimer posted.

Tommy

 

[Bretny]

Your making this really complex to plug a block heater in. Use an extension cord from the front,over the mirror and to the plug behind the truck.

 

[Stuart in MN]

I have never parked anywhere where I can plug my truck in without an extension cord so I just use a short one that is long enough to plug in at the front bumper if I pull in or back in. I really don't see any problem with this. I also loop it over the drivers door mirror so I can't forget to unplug it.

This is what I'd do. Looping the cord over the driver's door mirror is a good idea, I know it's saved me from forgetting to unplug the car.

 

[Fasthotrod]

If it were me, I'd probably use a power relay... perhaps something like this:

https://www.amazon.com/dp/B0078S7J3S/?tag=atomicindus08-20

So the first question I have is, which plug will be the 'primary' one that you plug in the most, and which will be used less often? (Front vs. rear?) I ask because of how we will wire up the relay.

Assuming that you use the rear plug more than the front:

Put the heater connections on the switched terminals 4 & 8.

Put the front plug wires on terminals 2 & 6 with a jumper from 2 to 0 and another jumper from 6 to 1.

Put the rear plug wires on terminals 3 & 7.

The rear power is the 'default' setting so when you plug in the rear plug, the heater comes on through the normally closed contacts between 3 & 4, and 7 & 8.

When you plug in the front plug, power goes to terminals 2 & 6 and jumps over to the coil of the relay to pick it up and change state. Contacts 6 & 8 close, and contacts 2 & 4 close. Now power is going to the heater, and the rear terminals are 'dead' and without power.

If it were me, I'd use a three-prong plug and three wires and connect the ground wires on both ends to the same point on the chassis with a ground screw. I would also keep the hots and neutrals on the same side of the relay. (Hots to 2, 3, and 4 - Neutrals to 6, 7, and 8.)

The datasheet for the relay can be found here:

https://www.mouser.com/datasheet/2/357/105A_W92-8723.pdf

I've included a diagram so you can see what I mean.

Hope this helps.

Mark

 

[teamextreme]

If it were me, I'd probably use a power relay... perhaps something like this:

https://www.amazon.com/dp/B0078S7J3S/?tag=atomicindus08-20

So the first question I have is, which plug will be the 'primary' one that you plug in the most, and which will be used less often? (Front vs. rear?) I ask because of how we will wire up the relay.

Assuming that you use the rear plug more than the front:

Put the heater connections on the switched terminals 4 & 8.

Put the front plug wires on terminals 2 & 6 with a jumper from 2 to 0 and another jumper from 6 to 1.

Put the rear plug wires on terminals 3 & 7.

The rear power is the 'default' setting so when you plug in the rear plug, the heater comes on through the normally closed contacts between 3 & 4, and 7 & 8.

When you plug in the front plug, power goes to terminals 2 & 6 and jumps over to the coil of the relay to pick it up and change state. Contacts 6 & 8 close, and contacts 2 & 4 close. Now power is going to the heater, and the rear terminals are 'dead' and without power.

If it were me, I'd use a three-prong plug and three wires and connect the ground wires on both ends to the same point on the chassis with a ground screw. I would also keep the hots and neutrals on the same side of the relay. (Hots to 2, 3, and 4 - Neutrals to 6, 7, and 8.)

The datasheet for the relay can be found here:

https://www.mouser.com/datasheet/2/357/105A_W92-8723.pdf

I've included a diagram so you can see what I mean.

Hope this helps.

Mark

Winner.
This is what I was going to suggest. We use this setup sometimes on control panels that have dual power feeds, it's basically a ghetto-fabbed ATS switch.

 

[Angelfire]

I'd go the power relay path myself. I used these for my plugs which I installed on my bumper (cheaper than the one you linked earlier). They seem to be pretty good quality.
Cheers.

 

[toplessHO]

twistlok female plug from heater to a recessed twistlok male receptacle.
Then make a cheater that does the male twistlok receptacle to a 15a male plug.
just move the cheater cord(can be 1 ft long) to which ever end you plug into.
This then puts the unused end as a female twistlok,without any exposed live parts.
Similar setups are used with small portable generators.

 

[alfredeneuman]

Then make a cheater that does the male twistlok receptacle to a 15a male plug.
just move the cheater cord(can be 1 ft long)

AKA "Suicide Cord". A very bad suggestion.
There is no such thing as a male twistlock receptacle it's called a plug or a cap.

 

[Fasthotrod]

Winner.
This is what I was going to suggest. We use this setup sometimes on control panels that have dual power feeds, it's basically a ghetto-fabbed ATS switch.

Ahem... I prefer Ghetto Engineering, thank you!

Mark