logical
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It offers an unbiased, non-partisan position.
240 V electrical
- Thread starter MikeC55
- Start date
A.K.A. - Useless
wyliesdiesels
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I've got a motor with a Rockwell Jam protection (high overload) relay on it, in addition to the starter.
djbmw
Well-known member
I said that because mm08822 referenced one of my previous comments. I had said that a 15 amp 2 pole breaker could also double as an overload and overcurrent device on this motor, as long as it DOES NOT trip with inrush current.seriously?
So... it was pointless to then talk about it tripping,.. but thats where the conversation went/continued... so I joked that if it continually tripped with inrush then the lift wouldnt work anyway.
*shrugs*
A couple more questions on upgrading the (100 amp, 6 circuit) sub-panel in detached garage. Since the new panel has room for 20 circuits and I plan to use more than 6, I think I'll need a main breaker that allows shutting power to the whole sub-panel without having to go into the house to main panel feed. Makes sense if you need to shut the garage down in a hurry. Looking at the panel I bought (which is intended to be a sub-panel), I don't think I can install a main disconnect breaker in the panel; it would need to be another small box for just the main shut-off breaker which then feeds this sub-panel. It also seems that in CT, for a detached garage using a sub-panel, I would need to install a grounding rod (even though neutral and ground are separated, as they should be for a sub-panel). The electrician who installed the original sub-panel, did not install a ground rod. I'm curious if you would expect any ground loop issues if your ground bar in the sub-panel is connected to both, the main panel ground wire and the new ground rod (next to garage)?
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Cruzan80
Well-known member
Yes, any detached structure with a subpanel should have both grounding rods as well as connecting to the "supply" panel's ground via wire. I will let other, more knowledgeable people chime in with the why (I understand it, but can't explain it via text as well as others I have seen on here do it).
IIRC, the ground rods are subject to the same requirements as a main (if only one, you need to measure and ensure something, so most people just drive two as there is no measuring involved in that case).
yatg
Well-known member
That's a SqD Homeline panel.
You can get a main breaker for it.
Replace the main lugs with a QOM100VH (assuming you've got a 100A or less feed).
wyliesdiesels
Well-known member
2 ground rods are actually required. the electrician that installed the subpanel didnt know what they were doing
no such thing as a ground loop between grounding electrodes. why? because under normal circumstances, there is no current flowing on ground rods. even there were, there would be no such thing as a ground loop because current returns to its source. it would circle around between grounding electrodes. ground loops is something that happens in audio systems...
theoldwizard1
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Many things use 120V to run auxiliary items like timers.
theoldwizard1
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It happens in cars also ! Run a wire from the negative post of the battery to the back of the vehicle. Check for voltage between the wire and the frame.
That is not a "real world" example, but it does happen. One common mistake is to connect both ends of a braided shield to "ground".
Notice how you said 120v... But we are talking about 240v...
theoldwizard1
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I was answering the question "Why would you need neutral in a 240V circuit/outlet ?"
dave*99
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Not really. It you have a neutral and L1, L2 you have 120/240.
If you ask an electrician to run a 240V circuit in your house and he leaves out the unnecessary neutral.....
You got what you asked for. If you ask for a dryer receptacle, you get 120/240.
If you ask an electrician to run a 240V circuit in your house and he leaves out the unnecessary neutral.....
You got what you asked for. If you ask for a dryer receptacle, you get 120/240.
No...
If the voltage listed is "240v". Then it does not require a neutral, period!
Now if the voltage listed was 120/240v then it would be a different matter. That is not what is being discussed...
theoldwizard1
Well-known member
Then you had better specify the outlet type (NEMA) or at least the item that will use it !
theoldwizard1
Well-known member
Long ago ...
I purchased a commercial high volume laser printer for my company. I asked that the electricians install a 240v outlet (probably a 6-20R or a 14-20R). I don't remember what they actually installed, but it was not what I requested ! Then I was told, (most) commercial building don't have 240VAC, only 208VAC !
Luckily the equipment had a multi-tap input transformer !
I purchased a commercial high volume laser printer for my company. I asked that the electricians install a 240v outlet (probably a 6-20R or a 14-20R). I don't remember what they actually installed, but it was not what I requested ! Then I was told, (most) commercial building don't have 240VAC, only 208VAC !
Luckily the equipment had a multi-tap input transformer !
Usually most things that run that voltage specifically list input voltage is 208-240V for that very reason. And to your other reply before that they also usually say the NEMA outlet type. Here's a random Xerox spec for example:
- North America: 208–240 V, 50/60 Hz, 16 amps; requires 20A circuit, NEMA 6-20-R socket
- Europe: 220 –240 V, 50 Hz, 20 amps/requires 20A circuit, PCE Shark 023-6 mating socket
sparky 1971
Well-known member
The customer had better specify the NEMA configuration. If you tell me you need a 20 amp twotwenny, that's exactly what your going to get. Tell me it's 120/240, four wire (counting the ground), or it needs a neutral and that changes things. There is no 240 load that needs a neutral.
Cruzan80
Well-known member
Wylie, is it automatic that a detached structure needs two, or is it able to use one as long as it is measurable to a specific amount (IIRC, resistance to ground?), just like a main?
I know most people automatically jump to installing 2x, as there is no measurement needed, but wasnt sure if one was allowed at all on a detached subpanel.
wyliesdiesels
Well-known member
what happens when its hard wired?
you dont need to specify the receptacle. a 240v circuit that has auxiliary items that run on 120v would be specified as a 120v/240v circuit NOT a 240v circuit. not sure why this is so hard to grasp.
wyliesdiesels
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so they installed a 30a circuit?
wyliesdiesels
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you can use 1 grounding electrode but you have to have the equipment to prove 25ohms or less. i doubt you have the equipment which costs a lot of money
Cruzan80
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Agreed. I was just trying to make sure that I had the rules straight in my head, and the requirements didn't change from the main to a detached subpanel (not sure why it would, but also not my main job). I put in two when I did my garage. Thanks.
dave*99
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wyliesdiesels
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#6 solid cu doesnt need protection. #8 does
sparky 1971
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Depending on the jurisdiction, we might have to use #6 as a minimum but if it isn't protected it's #4. I automatically use 4 everywhere.
JohnX14
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We use #6 stranded to ground rods.
I'll agreed that you will never get under 25 Ohms to ground with ground rods. But I'll "argue" that the 2nd ground rod adds no value., despite being required by code. Although I don't think it's much of an argument, almost everyone in the industry agrees.
I'll agreed that you will never get under 25 Ohms to ground with ground rods. But I'll "argue" that the 2nd ground rod adds no value., despite being required by code. Although I don't think it's much of an argument, almost everyone in the industry agrees.
theoldwizard1
Well-known member
I don't recall the outlet they used, but it did not match the equipment ! They said "We don't stock that receptacle."
I had to get in my car, go to an electrical supply house and buy the receptacle myself ! They did install it.