DIYer has a lamp wiring question

[brgrt2T]

I’m a DIY’er. Or at least, if I have an electrical problem, I like to fix it myself. I couldn’t find an answer to my question after googling around a bit, and no electrician would give me an answer, so I thought I would try your forum. An answer would be greatly appreciated.

I have a desk lamp wired for 120 volts. It uses two 50-watt, bi-pin halogen flood bulbs. The bulbs are expensive and burn out quickly. And no LED bulb exists for my specifications. So I was thinking of rewiring my lamp for 12 volts, because 12-volt bulbs offer more options and are cheaper. The lamp can’t be taken apart, so I’m thinking of adding a transformer plug and splicing the two wires under the base. Is any of this feasible? I’m attaching a photo of the lamp.

Thanks,

Tamara

 

[littlespark]

I would say no, not feasible. You may not find a 12v lamp that has the same pin configuration as that in the lampholder.
Most lamps I know of have an LED equivalent. Is there a rating plate that shows the max W or a make/model/ serial no.?
It is certainly possible to cut the cables in the base and insert a transformer if there is enough space in there for it, but the problem with the lampholders still exists.

 

[DPG]

Can you post a picture of the bulb. As above, I'd be surprised if there is no LED alternative available.

And before anybody starts going off on one about me calling it a 'bulb', I am doing this intentionally to differentiate it from the 'lamp' as a whole.

 

[brgrt2T]

I would say no, not feasible. You may not find a 12v lamp that has the same pin configuration as that in the lampholder.
Most lamps I know of have an LED equivalent. Is there a rating plate that shows the max W or a make/model/ serial no.?
It is certainly possible to cut the cables in the base and insert a transformer if there is enough space in there for it, but the problem with the lampholders still exists.

Hi,

I did find a 12v bulb with the same GU5.3 base (all the specs are identical between the two bulbs). And no, no 120-volt LED equivalent exists. There is a 12-volt LED, but with a different socket.

So, is rewiring the lamp for 12 volts really as easy as splicing the wires and adding a transformer plug? Is there anything more I need to know to make the lamp operational and safe?

Thanks,

Tamara

 

[brgrt2T]

Can you post a picture of the bulb. As above, I'd be surprised if there is no LED alternative available.

And before anybody starts going off on one about me calling it a 'bulb', I am doing this intentionally to differentiate it from the 'lamp' as a whole.

 

[brgrt2T]

Here are images of the two bulbs. The Bulbrite is the 120 volt. The Eiko is the 12 volt.

 

[telectrix]

if you can physically fit the 12V bulbs in the lamp, then id fit 12V LED bulbs and connect via a LED driver that likes 120V input.

 

[brgrt2T]

if you can physically fit the 12V bulbs in the lamp, then id fit 12V LED bulbs and connect via a LED driver that likes 120V input.

I can't replace the socket, so I can't use LED bulbs.

So will adding the transformer and splicing the wire work? You don't seem to take to this idea. Is that right?

 

[Richard Burns]

There should be no particular problem with reducing the incoming voltage to the light fitting from 120Vac to 12V.
There should also be no problem with using LED bulbs in the fitting as they would be designed to the same physical size in many cases, this would save energy but would mean you would be best to obtain a 12Vdc LED driver instead of a 12Vac halogen transformer.
The critical point is to ensure that the connections you make to install the driver/transformer are safe, secure and enclosed and that the cable will not be able to be pulled out of the connections.

 

[telectrix]

those lamps in post #7 are MR16 base. sameas this LED
Philips CorePro LED spot ND 5-35W MR16 827 36D - http://theledspecialist.co.uk/philips-corepro-led-spot-nd-5-35w-mr16-827-36d-1791.html

 

[littlespark]

The OP is in America. Of course we can get LED equivalents in this country, but Trump has banned importing.
LED’s are also energy saving, and Donald Duck over there doesn’t believe in fake news global warming ... (tiny, tiny hands!!)

 

[brgrt2T]

I can't replace the socket, so I can't use LED bulbs.

So will adding the transformer and splicing the wire work? You don't seem to take to this idea. Is that right?

There should be no particular problem with reducing the incoming voltage to the light fitting from 120Vac to 12V.
There should also be no problem with using LED bulbs in the fitting as they would be designed to the same physical size in many cases, this would save energy but would mean you would be best to obtain a 12Vdc LED driver instead of a 12Vac halogen transformer.
The critical point is to ensure that the connections you make to install the driver/transformer are safe, secure and enclosed and that the cable will not be able to be pulled out of the connections.

Hi Richard,

You're right. I did find a perfect LED match for my halogen bulb, except for one thing. The LED bulb is white, and I need a silver one to match my lamp. The bulb is a visible part of the lamp, and its seating is silver. I even think this lamp was designed for a halogen bulb, since the colored light given off by the body of the bulb seems to be part of the look of the lamp (You can see a photo of the lamp in an attachment to an earlier post). I see the benefits of getting an LED, but I would like it to be silver.

It's time consuming finding the right bulb, since googling the specs will return anything and everything. Perhaps you can suggest some large LED bulb manufacturers, and I could try tracking down a bulb through their websites.

Thanks,

Tamara

 

[Richard Burns]

Perhaps something like this would suit?
Most LEDs tend to be flat white or heat sink corrugated silver, though some from China have flat matt silver backs, occasionally as the link above shows they are silvered glass.
I am not familiar with the suppliers you may have available to be able to recommend anyone in particular.

 

[telectrix]

get a white one and stick some kitchen foil on it. .

 

[DPG]

I think I'd just go and buy a new led lamp to be honest. Easier in the long run. Unless this thing has sentimental value or something.

 

[telectrix]

must have sentimental value, as it has the aestetics of a demented toad.

 

[brgrt2T]

Perhaps something like this would suit?
Most LEDs tend to be flat white or heat sink corrugated silver, though some from China have flat matt silver backs, occasionally as the link above shows they are silvered glass.
I am not familiar with the suppliers you may have available to be able to recommend anyone in particular.

Thanks Richard for the link. It's the right bulb. I even found one in warm white, which is the color I prefer. But now here is the real deal breaker. The bulb comes in a pack of six. And that makes no sense for me, because I don't need these bulbs for anything but my lamp. Unless there is some way to buy just two, without paying a premium, I'm stuck with the halogen bulb.

 

[Richard Burns]

Since you appear to want to use halogen lamps, then use halogen lamps. It is an easy solution and does not cause problems with transformers, dimmers, etc.
Be aware that you will be using approximately 90% more energy and that from about 2020 the halogen lamps will be unavailable following the energy efficiency measures applied by congress.
Cheapest LED I could find at 3000K not 2700K warmish but not as warm as halogen.

 

[brgrt2T]

Since you appear to want to use halogen lamps, then use halogen lamps. It is an easy solution and does not cause problems with transformers, dimmers, etc.
Be aware that you will be using approximately 90% more energy and that from about 2020 the halogen lamps will be unavailable following the energy efficiency measures applied by congress.
Cheapest LED I could find at 3000K not 2700K warmish but not as warm as halogen.

Hi Richard,

That's strange. The 5000K is offered as a single, but the same bulb at 3000K is offered only in a six-pack. I'll call the company tomorrow and see what my options are and how much the six-pack costs.

The reason I'm a bit wary of using the LED is that, in my experience, they are never as bright as the incandescent or halogen bulbs they supposedly comparable to. The halogen bulb I have now is 595 lumens (x 2, since I use two bulbs). The lumens of this LED bulb is only 500. And it has a 6.6 wattage, which is less than the 7 watts of the white LED that was originally suggested here.

How much of a difference do you think the 190 Lumens differential makes? It may still not be an absolute deal breaker for me, because the wattage is still higher than the 35 watt halogen bulbs I originally had in my lamp, which I found a bit dim.

Thanks,

Tamara

 

[Squid]

Can you post a picture of the bulbs.

 

[pirate]

Oh, really...?

I want some new bulbs/lamps
Here are some that are perfect!
No, there's 3 or 6 in a pack...
I only want 2!
Ermm...have the extras as spares?

Oddly enough, about 3 years ago I saw a lady in Homebase trying to find a single 50W halogen GU10...they were £2.50 each, but a 6 pack was a tenner...gotta feel for those on a limited budget, given 6 would have seen her out!
I bought the 6 pack, gave her 2 out of it in the car park...I mean, you would, wouldn't you?

I hate the way older folks are discriminated against that way. Go to Tesco...new steak slice waffle pastry thingies...2 for £2...but buy 3 and it's 6 for £3 effectively...but folks have a budget, don't want to eat the same thing 3 days in a row, can't store the extras...ffs, price them so everyone can benefit!
RANT OVER...sorry...

 

[brgrt2T]

Since you appear to want to use halogen lamps, then use halogen lamps. It is an easy solution and does not cause problems with transformers, dimmers, etc.
Be aware that you will be using approximately 90% more energy and that from about 2020 the halogen lamps will be unavailable following the energy efficiency measures applied by congress.
Cheapest LED I could find at 3000K not 2700K warmish but not as warm as halogen.

I can get the bulb as a single. I'll be going to Home Depot to look into the bulb and a transformer.

Thanks

 

[Richard Burns]

500lm should be a similar brightness compared to a halogen lamp.
Glad you can get the single LEDs, and I hope you can get a suitable DC driver for the lamps.

 

[brgrt2T]

500lm should be a similar brightness compared to a halogen lamp.
Glad you can get the single LEDs, and I hope you can get a suitable DC driver for the lamps.

Thanks

 

[brgrt2T]

Thanks

Can someone please supply the specs for the kind of LED driver I need. I get conflicting information about what I need. I'm even told I don't need a driver but a transformer.

Thanks,

Tamara

 

[Richard Burns]

Feit do not specify precisely the supply type needed: ac or dc.
Generally an LED will need a dc voltage, that sort of light bulb normally needs constant voltage, as opposed to constant current.
I attach the specification sheet for the type of bulb you may have.
This clarifies that each bulb is 6.6W and 12V.
Because you are running two of them at once you would need 13.2W as a minimum but this would mean you were running the power supply at maximum load, so perhaps a 15W or higher wattage supply would be better. Some examples of a simple plug in arrangement might be this one (24W) or this one (18W) the output is a 12V barrel plug which would mean you would either need to get a suitable socket to match and wire that onto the lamp or cut off the plug and carefully and safely join the cable to the lamp cable. other LED drivers may have flying leads to wire up to or just terminals to connect a plug and the lamp onto.
This may be something beyond what you wish to do, but is really as simple as it comes, however it does require some knowledge and a safe approach to electricity.
Occasionally manufacturers allow the bulb to work with 12 Vac supply, however if they are designed for dc the life time of the bulb will be reduced when using ac. A transformer would supply an ac output.

 

[brgrt2T]

Feit do not specify precisely the supply type needed: ac or dc.
Generally an LED will need a dc voltage, that sort of light bulb normally needs constant voltage, as opposed to constant current.
I attach the specification sheet for the type of bulb you may have.
This clarifies that each bulb is 6.6W and 12V.
Because you are running two of them at once you would need 13.2W as a minimum but this would mean you were running the power supply at maximum load, so perhaps a 15W or higher wattage supply would be better. Some examples of a simple plug in arrangement might be this one (24W) or this one (18W) the output is a 12V barrel plug which would mean you would either need to get a suitable socket to match and wire that onto the lamp or cut off the plug and carefully and safely join the cable to the lamp cable. other LED drivers may have flying leads to wire up to or just terminals to connect a plug and the lamp onto.
This may be something beyond what you wish to do, but is really as simple as it comes, however it does require some knowledge and a safe approach to electricity.
Occasionally manufacturers allow the bulb to work with 12 Vac supply, however if they are designed for dc the life time of the bulb will be reduced when using ac. A transformer would supply an ac output.

Thanks, Richard, for the information. I'll Feit on Monday.

 

[brgrt2T]

Thanks, Richard, for the information. I'll Feit on Monday.

Hi Richard,

Feit says the bulb is both AC/DC. It also comes with an internal LED driver. Apparently, most LED bulbs come with drivers and don’t need transformers. Thus while feit stocks halogen transformers, I’d have to look elsewhere for an LED driver. I guess drivers are so hard to find because most residential bulbs don’t need then.

I don’t understand the examples you provided of the kind of plug-in arrangement I could use. The page shows adaptors, not drivers or transformers. Are you saying I can use adaptors in place of transformers?

I was talking to an electrical supply place, and the guy was very surprised that my lamp was wired for 120 volts. He suggested that the lamp might have an internal transformer. Do you think that’s a possibility? I’m looking for a nearby electrician to have the circuit tested. Would I damage the lamp, or explode the bulb, if I popped in a 12V bulb to test the circuit?

You say in your last sentence that: “A transformer would supply an ac output.” But if the bulb has a built-in driver, would it work DC?

Thanks,

Tamara

 

[Richard Burns]

I think that it may be too complicated for me to attempt to explain the various means of using varying voltages.
If this is too complex to follow then it may be something that it would be safer to get the electrician to do if he comes over. It would take about 20 minutes, if he has the parts.
If you put a 12V bulb into a 120Vac light fitting then it will fail instantly. If your supply voltage is 120Vac then it is simple to have a lamp using that voltage and it would not have a transformer in the lamp.
Adaptors is the name given to a switched mode power supply that provides a dc voltage output in a similar manner to an LED driver, but they are more readily available and cheaper.
If Feit state that the bulbs can use ac or dc then you can use either an ac or a dc supply at 12V and the internal circuitry of the bulb will provide the correct input to the LEDs in the bulb.
Some halogen transformers have a minimum wattage required to run which may mean they would not work with only 13.2W load so if you buy one of them then check the minimum as well as the maximum load.

 

[brgrt2T]

I think that it may be too complicated for me to attempt to explain the various means of using varying voltages.
If this is too complex to follow then it may be something that it would be safer to get the electrician to do if he comes over. It would take about 20 minutes, if he has the parts.
If you put a 12V bulb into a 120Vac light fitting then it will fail instantly. If your supply voltage is 120Vac then it is simple to have a lamp using that voltage and it would not have a transformer in the lamp.
Adaptors is the name given to a switched mode power supply that provides a dc voltage output in a similar manner to an LED driver, but they are more readily available and cheaper.
If Feit state that the bulbs can use ac or dc then you can use either an ac or a dc supply at 12V and the internal circuitry of the bulb will provide the correct input to the LEDs in the bulb.
Some halogen transformers have a minimum wattage required to run which may mean they would not work with only 13.2W load so if you buy one of them then check the minimum as well as the maximum load.

Hi Richard,

I understand everything you wrote, but I still have a question. Can I pop a 12-volt bulb into my lamp to test whether my lamp functions at both voltages? My thought is that my lamp may have an internal transformer. If the bulb doesn't light, that gives me my answer. I just want to know from you that I won't damage my lamp or have the bulb explode in my face with this experiment.

Thanks,

Tamara

 

[Richard Burns]

If you put a 12V bulb into a 120Vac light fitting then it will fail instantly.

Hi Richard,

I understand everything you wrote, but I still have a question. Can I pop a 12-volt bulb into my lamp to test whether my lamp functions at both voltages? My thought is that my lamp may have an internal transformer. If the bulb doesn't light, that gives me my answer. I just want to know from you that I won't damage my lamp or have the bulb explode in my face with this experiment.

Thanks,

Tamara

A 12V bulb in a 120V supply will probably just light brightly for a fraction of a second and then burn out, it might go with a bang, it might trip the supplying circuit, it might explode, but not too likely, do not try this.

 

[brgrt2T]

A 12V bulb in a 120V supply will probably just light brightly for a fraction of a second and then burn out, it might go with a bang, it might trip the supplying circuit, it might explode, but not too likely, do not try this.

OK. Thanks.

 

[brgrt2T]

I think that it may be too complicated for me to attempt to explain the various means of using varying voltages.
If this is too complex to follow then it may be something that it would be safer to get the electrician to do if he comes over. It would take about 20 minutes, if he has the parts.
If you put a 12V bulb into a 120Vac light fitting then it will fail instantly. If your supply voltage is 120Vac then it is simple to have a lamp using that voltage and it would not have a transformer in the lamp.
Adaptors is the name given to a switched mode power supply that provides a dc voltage output in a similar manner to an LED driver, but they are more readily available and cheaper.
If Feit state that the bulbs can use ac or dc then you can use either an ac or a dc supply at 12V and the internal circuitry of the bulb will provide the correct input to the LEDs in the bulb.
Some halogen transformers have a minimum wattage required to run which may mean they would not work with only 13.2W load so if you buy one of them then check the minimum as well as the maximum load.

Hi Richard,

I hope this will be the last time I bother you with a question. But I want to make sure I understand what you say here:

“If Feit state that the bulbs can use ac or dc then you can use either an ac or a dc supply at 12V and the internal circuitry of the bulb will provide the correct input to the LEDs in the bulb.”

Are you saying that if an LED bulb can use ac or dc, I don’t need an LED transformer to step down the voltage in my lamp to 12 volts?

Thanks,

Tamara

 

[Richard Burns]

You can use either 12Vac or 12Vdc, you cannot use 120Vac or 230Vac.
That is what I mean when I say you can use ac or dc at 12V.

Just buy a transformer or driver or power supply or adaptor that will input 120Vac and will output either 12Vac or 12Vdc and will operate when it has a load of 13.2W i.e. its minimum rating is below 13W and it maximum rating is above 14W.
Then wire this into your power cable to the lamp: safely, in a box and with no strain on the connections, because the cable is clamped.
Plug in the light bulbs, plug in the power supply and the lamp should work OK.

 

[brgrt2T]

Hi Richard,

I finally rewired the lamp yesterday, and it turned out to be very easy. But here's the strange thing. The LED bulb is as hot as my halogen bulb. How is this possible? Do you think there is a problem with the rewiring?

Tamara

 

[Richard Burns]

A halogen bulb will operate at about 200°C external and 400°C internal and an LED bulb will fail when the LED exceeds 70°C.
An LED bulb will get hot, but only enough so that you would not wish to touch it for a period of time, not generally enough to burn you.
If the temperature of the bulb exceeds this then it will fail in short order.
A higher temperature would be experienced if the voltage was higher than specified but the bulb would not last very long and would be very bright.
If the bulbs are the same temperature as halogen bulbs then they are probably not LED bulbs but halogen bulbs.

 

[brgrt2T]

The bulbs are LED. You can search for the specs by entering: "feit bulb bpexn/930ca" into the search bar. The bulbs are so bright that I had to remove one, and even then the remaining light is bright. It almost hurts my eye.

Do you think the bulb is wacky or is something wrong with my wiring? I got the adapter that you linked me to.

Can the bulb ruin my lamp? I have to wait till after Labor Day to get in touch with the manufacturer, but I need the light till then.

 

[Richard Burns]

Led bulbs tend to have very concentrated light source that would be inconvenient to look at directly, but then again halogen are fairly similar in comparison to the style of bulb you have.
Brightness wise it should be a close match to a halogen bulb's brightness for illuminating an area, the beam angle is similar and the light output should be similar.
If the output is significantly brighter then I would feel there is something wrong somewhere but I cannot understand what could cause this, any errors in wiring should make the bulbs dimmer or fail to work, it would only be by supplying something like a 24V supply that the bulbs would be very hot and bright (and probably fail soon) but the type of power supply I suggested cannot supply a different output voltage, even if the input voltage were 240V the adaptor should be able to cope with this and still provide 12V output.
If the bulbs were wired in series in the lamp then they would be now very dim, if the adaptor was supplying 120V then the bulbs should fail instantly.
Possibly worth checking that the adaptor is a 12V power supply and not a 24V one and is also not one that has an adjustable choice of output voltages and been set on the wrong setting, usually a rotary or slide switch somewhere.
Other than that I am lost as to the cause.

 

[brgrt2T]

I checked the specs on the adapter, and they are as advertised. The output is 12 VDC, and there is no adjustment possible. I’m attaching its spec sheet.

I have another question. When I pulled the plug from the wall to check the specs on the adapter, one of the wires pulled loose. The connector holds only about ⅜ of an inch of stripped wire in its slots. (I’ve attached a screenshot so you can see.) I tightened the screws as far as they would go. Obviously, it didn't do the job. Should I put electrician's tape around the end of the wires? Does this connector sound safe to you?

Thanks,
Tamara

I have another question. When I pulled the plug from the wall to check the specs on the adapter, one of the wires pulled loose. The connector holds only about ⅜ of an inch of stripped wire in its slots. (I’ve attached a screenshot so you can see.) I tightened the screws as far as they would go. Obviously, it didn't do the job. Should I put electrician's tape around the end of the wires? Does this connector sound safe to you?

 

[DPG]

If the wires are pulling out of the terminal then I would try doubling the wire back, ie. so that there is twice the thickness of conductor.

Bearing in mind the issues you are having, I would be tempted just to buy a new lamp all together. It can't be worth all this surely?

 

[Marvo]

As DPG says, I'd cut both wires back a bit to make them the same length, restrip them and double them over to give a better grip when they're screwed back in.

 

[gnuuser]

an led is a diode and can use either ac or dc (dc must be in the correct polarity)
but the voltage level must be within the limits of the led. often led kits can come with transformers and limiting resistors but not always.

 

[DPG]

This is not a bare LED, but a lamp designed for 12V use.

 

[brgrt2T]

I'll try doubling the wire, but I'm not sure there is enough room in the slot to accommodate a doubled wire. I'll call the seller tomorrow and see what they say.

The lamp is very functional, and I want to keep it. These are minor setbacks.

Thanks,
Tamara

 

[Marvo]

There's definately room in the slot for doubled over wire....promise.

 

[brgrt2T]

Good.

 

[brgrt2T]

Hi Richard,

I called the place that sold me the adapter. Everything is OK. The guy tested his own bulb and found that it also ran hot. He also tested the power the bulb was drawing from the wall, and it was 6.7 watts. Pretty close to the bulb rating. Now I'll just have to buy lower wattage bulbs so I don't burn my eyes out.

Thanks for all your help. I couldn't have done this without you.

Tamara

Led bulbs tend to have very concentrated light source that would be inconvenient to look at directly, but then again halogen are fairly similar in comparison to the style of bulb you have.
Brightness wise it should be a close match to a halogen bulb's brightness for illuminating an area, the beam angle is similar and the light output should be similar.
If the output is significantly brighter then I would feel there is something wrong somewhere but I cannot understand what could cause this, any errors in wiring should make the bulbs dimmer or fail to work, it would only be by supplying something like a 24V supply that the bulbs would be very hot and bright (and probably fail soon) but the type of power supply I suggested cannot supply a different output voltage, even if the input voltage were 240V the adaptor should be able to cope with this and still provide 12V output.
If the bulbs were wired in series in the lamp then they would be now very dim, if the adaptor was supplying 120V then the bulbs should fail instantly.
Possibly worth checking that the adaptor is a 12V power supply and not a 24V one and is also not one that has an adjustable choice of output voltages and been set on the wrong setting, usually a rotary or slide switch somewhere.
Other than that I am lost as to the cause.

Led bulbs tend to have very concentrated light source that would be inconvenient to look at directly, but then again halogen are fairly similar in comparison to the style of bulb you have.
Brightness wise it should be a close match to a halogen bulb's brightness for illuminating an area, the beam angle is similar and the light output should be similar.
If the output is significantly brighter then I would feel there is something wrong somewhere but I cannot understand what could cause this, any errors in wiring should make the bulbs dimmer or fail to work, it would only be by supplying something like a 24V supply that the bulbs would be very hot and bright (and probably fail soon) but the type of power supply I suggested cannot supply a different output voltage, even if the input voltage were 240V the adaptor should be able to cope with this and still provide 12V output.
If the bulbs were wired in series in the lamp then they would be now very dim, if the adaptor was supplying 120V then the bulbs should fail instantly.
Possibly worth checking that the adaptor is a 12V power supply and not a 24V one and is also not one that has an adjustable choice of output voltages and been set on the wrong setting, usually a rotary or slide switch somewhere.
Other than that I am lost as to the cause.

Led bulbs tend to have very concentrated light source that would be inconvenient to look at directly, but then again halogen are fairly similar in comparison to the style of bulb you have.
Brightness wise it should be a close match to a halogen bulb's brightness for illuminating an area, the beam angle is similar and the light output should be similar.
If the output is significantly brighter then I would feel there is something wrong somewhere but I cannot understand what could cause this, any errors in wiring should make the bulbs dimmer or fail to work, it would only be by supplying something like a 24V supply that the bulbs would be very hot and bright (and probably fail soon) but the type of power supply I suggested cannot supply a different output voltage, even if the input voltage were 240V the adaptor should be able to cope with this and still provide 12V output.
If the bulbs were wired in series in the lamp then they would be now very dim, if the adaptor was supplying 120V then the bulbs should fail instantly.
Possibly worth checking that the adaptor is a 12V power supply and not a 24V one and is also not one that has an adjustable choice of output voltages and been set on the wrong setting, usually a rotary or slide switch somewhere.
Other than that I am lost as to the cause.