There are always exceptions to any rule. But they are rare, and when such substitutions are made, all efforts must be taken to ensure no-one is at any risk. If there is the slightest doubt, don't do it, even if it means not lighting that rare lamp. In any case, you wouldn't want to destroy a lamp you'd waited years to acquire and may never find again, would you..?

By suitable, I mean the replacement still allows the bulb to run at the correct voltage and current (or something very close to it).
That being said, you do make a good point on not destroying a rare bulb by running it on gear that horrendously overdrives it.

I agree, just do your research, ask around, someone has been there before you.

There are always exceptions to any rule. But they are rare, and when such substitutions are made, all efforts must be taken to ensure no-one is at any risk. If there is the slightest doubt, don't do it, even if it means not lighting that rare lamp. In any case, you wouldn't want to destroy a lamp you'd waited years to acquire and may never find again, would you..?

Yeah that's about all there is to it. Hands down no BS. Without the proper gear it just don't get lit. There's just no excuse for destroying that rare one of a kind lamp simply because you saw it done elsewhere.

Even with the proper gear I have always been gun-shy about lighting up my rare lamps. You never know if over the many years if any air could have leaked in or if a little part dislodged setting the stage for a short-circuit inside the lamp, etc...

Even with the proper gear I have always been gun-shy about lighting up my rare lamps. You never know if over the many years if any air could have leaked in or if a little part dislodged setting the stage for a short-circuit inside the lamp, etc...

True that! 
That’s why when my SLI/H bulb arrives, I’ll light it up once to check that it works, then put it into safe storage for preservation. ^_^

Even with the proper gear I have always been gun-shy about lighting up my rare lamps. You never know if over the many years if any air could have leaked in or if a little part dislodged setting the stage for a short-circuit inside the lamp, etc...

I've always at least tried it. With incandescents it's relatively easy if you have a Variac. I just wind up the voltage very, very slowly until I see the filament just start to glow. If it seems ok, I'll increase voltage to about half way and then probably leave it at that if it's a very rare lamp like Barnaby. He's a special case though, so he won't be lit again, we've got a display case on order and he'll go in that when it gets here.

But if I've got the gear, I'll at least attempt to light it, whatever it is. To me, there's not a lot of point in having a lamp if you can't at least do that. I've always believed lamps were meant to be lit 

Speaking of Barnaby, that’s one impressive find! I would LOVE to have a bulb like that one!   

Speaking of Barnaby, that’s one impressive find! I would LOVE to have a bulb like that one!   

It was totally unexpected; we met up with another collector to pick up some lamps we'd bought on eBay, and he kept rooting around in the back of his van saying "have you got one of these..?" "No" we'd reply, "do you want one..?" and this went on for ages until we'd amassed 75 lamps over and above the three we'd paid for 

We had to stop him in the end as we had no more room in our own vehicle 

I've always at least tried it. With incandescents it's relatively easy if you have a Variac. I just wind up the voltage very, very slowly until I see the filament just start to glow. If it seems ok, I'll increase voltage to about half way and then probably leave it at that if it's a very rare lamp like Barnaby. He's a special case though, so he won't be lit again, we've got a display case on order and he'll go in that when it gets here.

But if I've got the gear, I'll at least attempt to light it, whatever it is. To me, there's not a lot of point in having a lamp if you can't at least do that. I've always believed lamps were meant to be lit 

Another inherent danger facing rare lamps (and any others for that matter that we have) is handling them. That is exactly how they can easily break or get damaged. And as I look back, I have lost a few medium rare lamps on account of them slipping out of my hands, rolling off a table, hitting another bulb in a storage carton, etc, etc. When this happens the disaster seems to be over before we know what has happened. So, I AVOID moving my good and respected lamps around because of prior misfortunes. Even being as very careful (as I am) these things can and still can happen. Most of my lamps are displayed on wall shelves and I leave them right there, period.

Same here. I always use cotton gloves when handling any lamp, even if they don't strictly need it. It's for two reasons; one I don't like fingerprints on glass and two it's just in case a lamp does need special handling and I forget. If I always do things the same way, then it's less likely I'll make a mistake. I treat every lamp as rare, even if it's a common household incandescent.

We're still in the process of fitting shelves and things, it's a work in progress. We don't have a lot of space here, so it's difficult 

I've always at least tried it. With incandescents it's relatively easy if you have a Variac. I just wind up the voltage very, very slowly until I see the filament just start to glow. If it seems ok, I'll increase voltage to about half way and then probably leave it at that if it's a very rare lamp like Barnaby. He's a special case though, so he won't be lit again, we've got a display case on order and he'll go in that when it gets here.

But if I've got the gear, I'll at least attempt to light it, whatever it is. To me, there's not a lot of point in having a lamp if you can't at least do that. I've always believed lamps were meant to be lit 

MVs can be brought to a nice glow using a transformer from a bug zapper. The 4kv going into the lamp is only at 15ma maximum ... but still be very careful unless you are on those UL-approved rubber pills. By applying this high-voltage low-current energy, you are simply illuminating the argon in the arc tube (this is the starting gas). Albeit, the lamp will not illuminate very brightly but the effect is quite  nice. It will not glow any brighter than from when you first applied power to it. I have not tried this yet on MH or HPS lamps. Also I have not seen any high voltage arcing between metallic points inside the bulb that are close together.
 

<Admin edit - quotes fixed>

MVs can be brought to a nice glow using a transformer from a bug zapper. The 4kv going into the lamp is only at 15ma maximum ... but still be very careful unless you are on those UL-approved rubber pills. By applying this high-voltage low-current energy, you are simply illuminating the argon in the arc tube (this is the starting gas). Albeit, the lamp will not illuminate very brightly but the effect is quite  nice. It will not glow any brighter than from when you first applied power to it. I have not tried this yet on MH or HPS lamps. Also I have not seen any high voltage arcing between metallic points inside the bulb that are close together.
 

I use this to check discharge lamps, all it really does is check vacuum, but it does light up the arc tube quite nicely on most lamps.

I use this to check discharge lamps, all it really does is check vacuum, but it does light up the arc tube quite nicely on most lamps.

I have never seen one of those, what a cool device!
Would make for a dandy Holiday gift too for HID lovers like myself 

I got it on UK eBay quite cheap as it was second hand, but try here.

Edit - here is the manufacturer's site, quite a good price there, too.

Same here. I always use cotton gloves when handling any lamp, even if they don't strictly need it. It's for two reasons; one I don't like fingerprints on glass and two it's just in case a lamp does need special handling and I forget. If I always do things the same way, then it's less likely I'll make a mistake. I treat every lamp as rare, even if it's a common household incandescent.

We're still in the process of fitting shelves and things, it's a work in progress. We don't have a lot of space here, so it's difficult 

I forgot to mention about the fingerprints on the glass bulbs. To me it is annoying unless it happens to have been burned in by the installer decades ago. Other than that, the best way to remove oily fingerprints (I am sure many of you know this anyway... is to carefully swipe the affected area with a kleenex having some isopropyl alcohol on it. Always be sure to keep away from the etch! Yes, wearing light cotton gloves while lamp handling sounds like a great idea. I think they help with getting a better and more solid grip on the bulb and-or base.