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#32177 - 12/17/03 02:34 PM Visible power indicator  
derater  Offline
Member
Joined: Mar 2002
Posts: 179
Have a cust. who wants a way to tell when his power is on at panel.He wants to turn off main to run house via generator when power is out,but know when it comes back on.So connection would have to be before main.Any suggestions?


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#32178 - 12/17/03 06:47 PM Re: Visible power indicator  
Electricmanscott  Offline
Member
Joined: Jan 2002
Posts: 1,457
Holden, MA USA
Use a listed generator tranfer switch. One big enough to do the entire house will be automatic. Any other type will do a portion of the loads so when the remainder come on he will know. Do not rely on him switching the main as the transfer switch.


#32179 - 12/27/03 08:39 AM Re: Visible power indicator  
Trumpy  Offline


Member
Joined: Jul 2002
Posts: 8,211
SI,New Zealand
I wouldn't recommend the installation of indicators or such devices on the Line-Side of a Main Switch without asking the PoCo first.
Power companies get rather finnicky about things like this, especially where there is a chance that a Generator could back-feed into the Grid.
BTW, I hope that the guy has got a reasonably large generator, you'd be amazed how many people under-estimate the current draw of a few appliances.


Let's face it, these days if you're not young, you're old - Red Green grin

#32180 - 12/27/03 09:07 AM Re: Visible power indicator  
iwire  Offline
Moderator
Joined: Jan 2003
Posts: 4,391
North Attleboro, MA USA
Quote
He wants to turn off main to run house via generator when power is out,but know when it comes back on.


This would be a code violation and would be dangerous to utility workers.

Advise the customer strongly to do the right thing as Scott has said.

You should not even consider helping this customer back feed a panel with a generator.

Besides the moral responsibility you have, you will be liable injuries to the utility workers that get blasted by a back feed.


Bob Badger
Construction & Maintenance Electrician
Massachusetts

#32181 - 12/27/03 02:09 PM Re: Visible power indicator  
Wirenuttt  Offline
Member
Joined: Nov 2002
Posts: 267
Massachusetts
As long as there's a transfer switch involved, maybe your customer possibly lives in an off the beaten track neighborhood where he can't just look out his window and see street lights and the neighbors. So he's probably thinking he doesn't want to let the generator keep running unbeknownst to power being back on. I had a situation like this and simply placed a rated cabinet light into the main panel. Always lit when power was on, off when not.


#32182 - 12/27/03 02:29 PM Re: Visible power indicator  
iwire  Offline
Moderator
Joined: Jan 2003
Posts: 4,391
North Attleboro, MA USA
Wirenutt, I would be interested to know how you attached "a rated cabinet light into the main panel" on the line side of the service disconnect.

230.82 prohibits almost anything from being connected on the line side of the main service disconnect.


Bob Badger
Construction & Maintenance Electrician
Massachusetts

#32183 - 12/27/03 07:41 PM Re: Visible power indicator  
Trumpy  Offline


Member
Joined: Jul 2002
Posts: 8,211
SI,New Zealand
One way that a reasonable level of safety could be acheived, is by the use of 2 inter-locked contactors, so that only 1 can be energised at a time. [Linked Image]


Let's face it, these days if you're not young, you're old - Red Green grin

#32184 - 12/27/03 09:56 PM Re: Visible power indicator  
mvpmaintman  Offline
Member
Joined: Sep 2003
Posts: 123
Manhattan, Kansas, USA
If the guy wants to do it right use a transfer switch that will transfer back when the power is on. Anything else is way too risky.


#32185 - 12/28/03 06:57 AM Re: Visible power indicator  
iwire  Offline
Moderator
Joined: Jan 2003
Posts: 4,391
North Attleboro, MA USA
Hi Trumpy

The rules are pretty strict as far as transfer equipment especially ones that handle the whole service.

Quote
702.6 Transfer Equipment.
Transfer equipment shall be suitable for the intended use and designed and installed so as to prevent the inadvertent interconnection of normal and alternate sources of supply in any operation of the transfer equipment.
Transfer equipment and electric power production systems installed to permit operation in parallel with the normal source shall meet the requirements of Article 705.

Transfer equipment, located on the load side of branch circuit protection, shall be permitted to contain supplementary overcurrent protection having an interrupting rating sufficient for the available fault current that the generator can deliver. The supplementary overcurrent protection devices shall be part of a listed transfer equipment.

Transfer equipment shall be required for all standby systems subject to the provisions of this article and for which an electric-utility supply is either the normal or standby source.


Quote
230.82 Equipment Connected to the Supply Side of Service Disconnect.
Only the following equipment shall be permitted to be connected to the supply side of the service disconnecting means:

(1) Cable limiters or other current-limiting devices.

(2) Meters, meter sockets, or meter disconnect switches nominally rated not in excess of 600 volts, provided all metal housings and service enclosures are grounded.

(3) Instrument transformers (current and voltage), high-impedance shunts, load management devices, and surge arresters.

(4) Taps used only to supply load management devices, circuits for standby power systems, fire pump equipment, and fire and sprinkler alarms, if provided with service equipment and installed in accordance with requirements for service-entrance conductors.

(5) Solar photovoltaic systems, fuel cell systems, or interconnected electric power production sources.

(6) Control circuits for power-operable service disconnecting means, if suitable overcurrent protection and disconnecting means are provided.

(7) Ground-fault protection systems where installed as part of listed equipment, if suitable overcurrent protection and disconnecting means are provided.


As you can see transfer equipment is not listed, the only way to install transfer equipment that switches the entire service is to get a transfer switch that is also rated/listed as a service disconnect.

I could not put together a couple of contactors or even one contactor that was double throw to make my own transfer switch.

Many panel makers produce a panel with two mains that are mechanically interlocked so only one can be on at a time and are listed as service equipment.

Trumpy I know you know the dangers here but I think many people do not realize that under the right conditions that their little generator can back feed a POCO transformer and produce some high voltages.

Bob

[This message has been edited by iwire (edited 12-28-2003).]


Bob Badger
Construction & Maintenance Electrician
Massachusetts

#32186 - 12/28/03 10:41 AM Re: Visible power indicator  
Wirenuttt  Offline
Member
Joined: Nov 2002
Posts: 267
Massachusetts
IWire;
Real simple, just attach it to any circut breaker as you would a transformer for a door bell. Get a light that's 120 volts but rated at 250 or more.

~Andy


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