Electrical Wiring Question

Factual Questions
1

We have an above-the-range microwave that is direct wired to the black, green, and white wires coming from the wall.

We now want to add above and under-the cabinet lighting. Home Depot sells low wattage halogen kits for this purpose, such as those linked here:

http://www.homedepot.com/prel80/HDUS/EN_US/diy_main/pg_diy.jsp?CNTTYPE=PROD_META&CNTKEY=misc%2FsearchResults.jsp&BV_SessionID=@@@@1308720173.1059163162@@@@&BV_EngineID=ccccadcimefelmdcgelceffdfgidgkg.0&MID=9876&frmSearchStr=under%20cabinet%20lighting

Is it safe to direct wire such light to the same wires as the Microwave? I’m envisioning just capping all the wires together to the electrical wires coming out of the wall…

…not sure if that will work, is proper, or safe. Any info?

Thanks

2

I would do it, but i would try and wire it to code.

ie use a junction box if needed, use marretts, etc.

MtM

3

As long as you’re installing low wattage lights. Flouresents (sp?) I’m assuming. You should be ok. If not you’ll know when you trip a breaker.

4

What is the current draw (amperage) of the new lights?

Microwaves tend to be high draw devices - wiring in to the same circuit is fine, provided you do not exceed the circuit design current, but you should probably check this. Most discrete household circuits are 15 A, but you can confirm this by looking at your breaker box. Note which lights, appliances and outlets are disabled by the breaker which disables the microwave, and verify that when you add up the rated amperages of these devices, it doesn’t exceed the rating of the breaker. If it does, you need to put the lights on a different (or altogether new) circuit.

When wiring, you also need to ensure that the wire gauge is sufficient for the total current draw. You are probably OK there, because in new construction, the wires need to be at least good enough for the maximum current on that circuit. This is why you can’t simply switch the breaker out for a higher current one - the breakers protect the wiring, and by increasing the breaker trip current, you create the possibility that the wiring will go first - EXTREMELY DANGEROUS.

Having said that, again you’re probably OK. Most household circuits do not carry their full design load as constructed. When you wire the new lights, though, make sure that any new wires are at least the same gauge as the existing in-wall wiring (gauge number decreases as wire gets bigger). Use proper Marrette connectors, and don’t leave any loose or exposed wiring.

Oh, one more thing: BLACK = LINE (hot), WHITE = NEUTRAL, GREEN = SAFETY GROUND (chassis) - this is the standard, but be prudent and don’t count on it… your electrician could have been smoking something. Play it safe and test with a voltmeter or circuit tester. Also, make sure the breaker is opened (OFF) prior to messing around with the wiring.

Hope that helps.

5

The lights you linked to are not designed to be hardwired into your house’s electrical wiring.

The transformer in that kit plugs into the wall, and then it puts out 12 volts…yes, the lamps are the same voltage as a car.

Theoretically, you could cut the wall plug off the transformer and wire it right into the house, but that would likely be against code.

If there is no electrical outlet near the place you want to mount the lights, the best solution would be to proplery install a normal outlet, and then plug the transformer into it.

Or, if you must, plug in the transformer in a remote location, but use more wire to extend its output to reach the bulbs. This way, if you make a mistake or a poor connection, you’re doing it on the 12-volt side, where you’re unlikely to electrocute yourself, start fires, etcetera.

6

I would add to the comment about directly hard-wiring the light: I would either install an outlet, as suggested, or an in-line switch. If the ballast decides to melt down at some point, you have no means of disconnecting the light without running to the breaker panel. The breaker may not trip. As far as load, 60 watts total is only a half amp and the microwave is usually only on for a matter of seconds or a few minutes (not a continuous load). You’re probably safe connecting to the existing circuit.

7

Oops. Disregard the stuff about the ballast and the inline switch. That’ll teach me not to look at the link first!

8

Thanks for all the advice… an update:

We took the over-the-range microwave off the wall last week, and noted, as mentioned above, that it listed a 15 amp circuit as a requirement, and would draw as much as 12 amps on its own.

However, we shut off the breaker before taking it off, and noticed that entire side of the house went off. The 15 amp line attached to the microwave also powers the outlets in 2 rooms and the bathroom (including fixture).

A whole lot of electrical equipment is in one of those rooms, including 2 computers, one attached to a TV, the other to a 19 inch CRT, home networking equipment, and the cable modem. This solved the mystery as to why my UPS power supply would kick in for a sec when the microwave was turned on - seems like that circuit is overloaded.

So, we’re having an electrician come in and run another line from the panel to kitchen to power the microwave alone. We’ll use the old line for the cabinet lights, and have him wire a switch to it.

I really wanted to avoid calling someone, but circuit wire seemed to be pretty near its limit (esp w/ the compus, which I would assume draw 2-5 amps a piece?)

Now to fix the plumbing - the stupid builder ran an polybutelyne line for it under the house foundation, and it cracked right as it comes out behind the fridge.

Thanks for all the advice.