generator plug in dryer outlet

What kind of circuit breaker protection would I have if I plugged my generator into the three wire dryer outlet, after tripping the main breaker, of course? Any suggestions?
simonmeridew

 

That depends on what kind of generator you have. You will have whatever protection is on your generator which may or may not be sufficient.

 

You have the protection of the dryer breaker and the breakers on the generator. Breakers work both ways.
You are going to get many posts telling you not to do this. Just make absolutely sure the main is off.

 

The problem with only tripping the main is that the neutral remains connected. A transfer switch opens ALL the conductors.

 

It seems I have seen transfers that disconnect neutrals and ones that dont. Is there a code for insisting the neutral be disconnected?

 

Not only don't do it, your not meeting the code requirements that allows you to do it.
Article 702 (NEC) covers your optional standby systems. A transfer switch is required
and is safe for yourself, and the power company. If the power was to go out, and for some
reason the main was not off you are supplying power to the incoming lines, The same
lines that most likely the service men are out working on in 10 below weather. You are
putting then in danger of thinking the power is off, I know it is their job to test, and they
will, but when they do, and then find where the unknown voltage is coming from, be
prepared to get your notice !!!

 

Linemen have been jolted by current feeding back thru the neutrals due to such setups while restoring lines. It has become so common they will generally throw a chain across to ground out before doing anything.

 

To determine whether the neutral must be switched with the ungroundee conductors at a transfer switch, you will have to determine if the neutral and ground are bonded together in the generator making it a seperately derived source or not.
The installation as proposed by the initial question is not compliant with code. You will never know that you forgot to trip the main, until someone is hurt.

 

Not to mention a male plug at each end of an extension cord.


Three words.....DON'T DO IT!!!

 

I am not condoning this practice but can someone explain the how the linemen can get shocked if ONLY the neutral is connected to the standby generator. The neutral is connected to the ground in the service panel. Since the neutral is already at ground potential what exactly creates the problem for the linemen.

 

You have spent five hundred to a thousand dollars on a generator but you won't spent two hundred for the equipment to hook it up right?

Current flow in the common neutral that serves several buildings does not create a likely hazard to the outside wiremen who are struggling in darkness and harsh weather to restore your electrical service. What does create a very real hazard to them and to you is human error. If any mistake occurs in the order of operations, if the water heater or air conditioner that is fed with two different meters develops an internal fault, If there is any defect in your main breaker then someone can be injured or killed.

I take it you don't have any teenage children who never listen but know everything, or any ever so helpful neighbors who will be happy to hook the set up in your absence but won't know what they are doing. And certainly you would never come home over tired from work or after a party were you have had some alcohol to find your lights out and try to hook up your generator set while impaired. Cords with two male caps are called suicide cords for a reason!

I guess all that is left to say is that the International Brotherhood of Electrical Workers is looking to make an example out of someone who harms one of their members with a generator back feed. Someone will get charged with manslaughter which will get bargained down to reckless endangerment but they will still spend some months in jail.

For some people their personal convenience is far more important then the lives of outside wiremen or even apparently their own family. If you are one of those folks then you will do what you please anyway. If, on the other hand, you would rather not be the guest of honor at a manslaughter trial you might want to find another way.

Let me offer just one suggestion that might give you the utility that you actually need. The only thing in your house that is hard wired that you cannot do without and stay in the house is the heating plant. Change the supply to the heating plant from hard wired to cord and plug. Many heating plants have a service cut off switch at the furnace or boiler that is the perfect place to make that change. You disconnect the wiring into the unit from that switch and replace it with cord and plug. You convert the switch itself to a receptacle and you have the problem whipped. During an outage you unplug the power to the heating plant from the outlet and plug it in to the extension cord from your generator. Your fridge, a table lamp, the TV, and anything else that your generator would actually carry would plug in the same way. This solution is far safer than a suicide cord and is no more expensive. By cord and plug connecting the loads you will have tighter control over what is plugged in so that you can avoid the generator breaker opening because your teenage daughter "just had to dry my hair."
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Tom

 

So why do you need a transfer switch that switches the neutral. Can't you just use one that switches the 2 hots.
I am just trying to understand the theory behind this. I am not trying to install this.

 

Electrical systems should be constructed so that it will take two failure to create a hazard. If the generator common winding connection point or X0 is bonded to the generator frame and the transfer switch does not open the neutral connection back to the main bonding jumper and the utility neutral then the earth ends up being a parallel conductor to the grounded conductor of the building wiring system. The amount of current that will travel over that unintended pathway will vary with the impedance of the grounding electrode system and the generator frames contact with the earth. IF any of the connections in the grounded conductor develop a high impedance then the voltage drop across the only remaining pathway will introduce a shock and arcing hazard. In the absence of that second pathway an open in the neutral would cause an immediate loss of function which would cause the user to instigate repair.
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Tom

 

joed

When the the generator neutral is bonded to the generator frame, the neutral must be switched to prevent current from flowing on the equipment grounding conductor.

 

Thanks for all your replies. I, like joed, was interested in the theoretical problems involved with a hookup of this type. I have no intention of doing this, especially after the information I received.
simonmeridew

 

Thank you. I sort of understand it.