ANOTHER ELECTRICAL QUESTION

[Industrial Toys]

I have run into many cases where I want to plug a fixed device into a UPS for instance. Like Automatic doors that are normally wired into a building.

Like, how would you take a circuit in your house, and plug end it to plug into a UPS?

There doesn't really seem to be any way to do this to code. Cab tire and extension cords are not for permanent use. And you can't put a plug on the end of some BX, although I do. One of those metal ones. But not to code.

 

[MossRoad]

Yep, it is crazy. And that is one for a subpanel, the ones for main panels are a lot more heavy-duty but a manual or automatic transfer switch is definitely the choice for myself.

All you need is a double-pole breaker in the first positions near your disconnect to take power from the generator, and a slide device to prevent the double-pole from being turned on if the disconnect is on. Pretty much anyone could look at an existing design and make their own with some sheet metal screws and a piece of plexiglass or metal for about $10. It's extremely inexpensive, and is a 100% isolation of the two power sources. The main disconnect has to be turned off before the interlock can be slid out of the way allowing the double-pole generator breaker to be made hot. Likewise, the main cannot be turned back on until the generator breaker is turned off.

Yet every time this great solution comes up, there's a couple members in particular that insist you need a transfer switch. You don't.

 

[MossRoad]

I have run into many cases where I want to plug a fixed device into a UPS for instance. Like Automatic doors that are normally wired into a building.

Like, how would you take a circuit in your house, and plug end it to plug into a UPS?

There doesn't really seem to be any way to do this to code. Cab tire and extension cords are not for permanent use. And you can't put a plug on the end of some BX, although I do. One of those metal ones. But not to code.

Put a twist-lock connector on its power cord. We did that with the furnace and well pumps in several houses.

 

[aczlan]

Here is the wiring diagram for the generator link device:

Looks like both hot wires (one from each generator) come in, feed into the 30 and 50 amp breakers, then go out to the hot on the 30 amp receptacle and both hots on the 50 amp receptacle.
The neutrals are connected together and to the neutral terminals on the receptacles and the grounds are similarly connected to the ground pins of the receptacles.
That gives it 120v from either hot to neutral and 0v from hot to hot (vs the 240v that is normal).
As such, anything that uses 240v only will see 0v and wont work (most will have a 3 wire cord). Anything that uses both 120v and 240v (most will have a 4 wire cord) will have the 120v part work, but not the 240v part.

I would love to use an interlock kit rather than a transfer switch. Much cheaper and easier and just as safe. However, my sub-panel (Siemens) does not have a main, only branch circuit breakers. The main for the sub-panel is in the outside panel.

OK, I have another confession to make. I do own a 5500 watt 240 volt generator. It is loud as all get out and the voltage fluctuates pretty wildly when a load is applied (like a compressor starting on a refrigerator, freezer or window ac). I'm very concerned about my electronics using this generator. I CAN use it if I have to. I just don't really want to if I can help it.

The 240v generator has a bonded neutral. (I just checked it) I know the smaller ones have a floating neutral. (Checked them too) If I do buy the 100 amp transfer switch I still do not know how to hook up the neutrals or grounds from either generator. That has been my only question from the beginning of this post. THANKS for your help and advice. I really do appreciate it.

Given that the generator will be running outside, I would install (or given your apparent experience level, perhaps have an electrician install) a transfer switch outside (after the breaker in the outdoor breaker panel), or with an interlock on the main breaker of the outdoor panel with a NEMA 14-50 inlet such as: Conntek GISB5-25 NEMA 14-5 Power Inlet Box & Power Cord Combo
then plug your generators into that, or a larger generator down the road.

Aaron Z

 

[MossRoad]

I have run into many cases where I want to plug a fixed device into a UPS for instance. Like Automatic doors that are normally wired into a building.

Like, how would you take a circuit in your house, and plug end it to plug into a UPS?

There doesn't really seem to be any way to do this to code. Cab tire and extension cords are not for permanent use. And you can't put a plug on the end of some BX, although I do. One of those metal ones. But not to code.

What where you trying to type with "cab tire"?

 

[Industrial Toys]

It's what flexible rubber cord is called here. Yes, dumb founded me too, when starting as an apprentice. Did a little looking. No one seems to know where the name originates.

So twist locks are OK for permanent service? On the end of rubber cord????

 

[aczlan]

It's what flexible rubber cord is called here. Yes, dumb founded me too, when starting as an apprentice. Did a little looking. No one seems to know where the name originates.

So twist locks are OK for permanent service? On the end of rubber cord????

Per: The History of Electric Wires and Cables - Robert Monro Black - Google Books (result #2) the St Helens Cable and Rubber Company used the same rubber extrusion process for rubber cord as they used to make rubber tires for cabs and carriages and they may have been the first to market with a rubber cord (vs some other type of insulator).

Aaron Z

 

[Industrial Toys]

Thanks. I always feared dying, never knowing. lol

 

[MossRoad]

It's what flexible rubber cord is called here. Yes, dumb founded me too, when starting as an apprentice. Did a little looking. No one seems to know where the name originates.

So twist locks are OK for permanent service? On the end of rubber cord????

Pretty much every piece of equipment at the Newspaper I worked at for 30 years was on twist lock connectors. All production equipment. All of the computer servers had twist lock connectors that went into receptacles on the back of UPS's. The UPS's had twist lock connectors that plugged into mounted outlet boxes that were fed from breaker panels.

Literally hundreds of pieces of machinery and computer hardware, all on twist lock plugs.

 

[Industrial Toys]

Sure. Seen it too. But all the machines, even if they would be in place forever, are deemed NOT part of the building.